Ekiwandiiko kino kitundu ku mulamwa gw’okunoonyereza “Advanced bioremediation technologies and synthetic organic compounds (SOC) recycling processes”. Laba emiko gyonna 14
Low molecular weight polycyclic aromatic hydrocarbons (PAHs) nga naphthalene ne substituted naphthalenes (methylnaphthalene, naphthoic acid, 1-naphthyl-N-methylcarbamate, n’ebirala) zikozesebwa nnyo mu makolero ag’enjawulo era nga zikola butwa mu nsengekera y’obutonde, zikyusakyusa ne/oba zireeta kkansa eri ebiramu. Ebirungo bino ebikolebwa mu butonde (SOCs) oba ebiwuka ebiyitibwa xenobiotics bitwalibwa ng’ebicaafu ebisookerwako era nga bya bulabe obw’amaanyi eri obutonde bw’ensi n’obulamu bw’abantu. Amaanyi g’emirimu gy’abantu (okugeza okufuula amanda ggaasi, okulongoosa amafuta, okufulumya omukka mu mmotoka n’okukozesebwa mu bulimi) ge gasalawo okukuŋŋaanyizibwa, enkomerero n’entambula y’ebirungo bino ebisangibwa buli wamu era ebiwangaala. Ng’oggyeeko enkola z’okulongoosa/okuggyawo mu ngeri ey’omubiri n’eddagala, tekinologiya ow’obutonde era atakuuma obutonde nga bioremediation, akozesa obuwuka obutonotono obusobola okusaanyaawo ddala POCs oba okuzifuula ebivaamu ebitali bya butwa, bivuddeyo ng’enkola endala etali ya bulabe, etali ya ssente nnyingi era esuubiza. Ebika bya bakitiriya eby’enjawulo ebibeera mu kika kya Proteobacteria (Pseudomonas, Pseudomonas, Comamonas, Burkholderia, ne Neosphingobacterium), Firmicutes (Bacillus ne Paenibacillus), ne Actinobacteria (Rhodococcus ne Arthrobacter) mu microbiota z’ettaka biraga obusobozi bw’okusaanyawo ebirungo eby’enjawulo eby’obutonde. Okunoonyereza ku nkyukakyuka y’ebirungo, ensengekera y’obutonde, n’okwekenneenya eby’obutonde (metagenomic analysis) bituyamba okutegeera obuzibu bw’enkyukakyuka y’ebiramu (catabolic complexity) n’enjawulo eriwo mu bitonde bino eby’obulamu ebyangu, ebiyinza okwongera okukozesebwa mu kuvunda kw’ebiramu okulungi. Okubeerawo kwa PAHs okumala ebbanga eddene kivuddeko okuvaayo kw’ebika by’okuvunda ebipya okuyita mu kukyusa obuzaale mu bbanga nga tukozesa ebintu by’obuzaale nga plasmids, transposons, bacteriophages, genomic islands, ne integrative conjugative elements. Enkola z’ebiramu n’obuzaale bw’ebiramu eby’enjawulo oba ebitundu eby’ekyokulabirako (consortia) bisobola okusobozesa okutereeza ebiramu mu ngeri enzijuvu, ey’amangu era ennungi eya PAH zino okuyita mu bikolwa eby’okukwatagana. Mu kwekenneenya kuno, essira tulitadde ku makubo ag’enjawulo ag’enkyukakyuka y’emmere n’enjawulo, ensengekera y’obuzaale n’enjawulo, n’okuddamu kw’obutoffaali/okukyusakyusa kwa naphthalene ne bakitiriya ezisaanya naphthalene ezikyusiddwa. Kino kijja kuwa amawulire agakwata ku butonde bw’ensi okukozesebwa mu nnimiro n’okulongoosa ebika okusobola okulongoosa obulungi ebiramu.
Enkulaakulana ey’amangu ey’amakolero (eby’amafuta, ebyobulimi, eddagala, langi z’engoye, eby’okwewunda n’ebirala) kivuddeko ebyenfuna by’ensi yonna okukulaakulana n’okutumbula embeera z’obulamu. Enkulaakulana eno ey’amaanyi evuddemu okukola ebirungo ebingi ebikoleddwa mu butonde (SOCs), ebikozesebwa okukola ebintu eby’enjawulo. Ebirungo bino eby’ebweru oba SOCs mulimu polycyclic aromatic hydrocarbons (PAHs), eddagala ly’ebiwuka, eddagala ly’omuddo, ebirungo ebikola obuveera, langi, eddagala, organophosphates, ebiziyiza ennimi z’omuliro, ebiwunyiriza ebiwunya, n’ebirala Bifulumizibwa mu bbanga, ebitonde eby’omu mazzi n’eby’oku ttaka gye biba n’ebikosa eby’enjawulo, ne bivaako ebikosa eby’obulabe ku bitonde eby’enjawulo nga tuyita mu kukyusa eby’obutonde n’ensengekera y’ekitundu (Petrie et al., 2015; Bernhardt et al., 2017; Sarkar et al., 2020). Ebintu bingi ebicaafu ebiwunya birina ebikosa eby’amaanyi era eby’okusaanyaawo ku bitonde bingi ebitaliiko kamogo/ebifo eby’enjawulo ebirimu ebiramu (okugeza ebiyiriro by’amasanga, ebiyiriro bya ice ebya Arctic/Antarctic, ennyanja ez’ensozi empanvu, ensenke z’ennyanja enzito, n’ebirala) (Jones 2010; Beyer et al. 2020; Nordborg et al. 2020). Okunoonyereza okwakakolebwa ku geomicrobiological kulaga nti okuteekebwa kw’ebintu ebiramu ebikoleddwa (okugeza obucaafu obuwunya) n’ebivaamu ku ngulu w’ebizimbe eby’obutonde (obutonde obuzimbibwa) (okugeza ebifo eby’obuwangwa n’ebijjukizo ebikoleddwa mu granite, amayinja, embaawo n’ebyuma) kwanguyiza okuvunda kwabyo (Gadd 2017; Liu et al. 2018). Ebikolwa by’abantu bisobola okwongera amaanyi n’okwonoona okwonooneka kw’ebiramu mu bijjukizo n’ebizimbe nga biyita mu bucaafu bw’empewo n’enkyukakyuka y’obudde (Liu et al. 2020). Ebintu bino ebicaafu ebiramu bikolagana n’omukka gw’amazzi mu bbanga ne bisenga ku nsengekera, ne bivaako okuvunda kw’ekintu ekyo mu mubiri n’eddagala. Okuvunda kw’ebiramu kumanyiddwa nnyo ng’enkyukakyuka eziteetaagibwa mu ndabika n’eby’obugagga by’ebintu ebiva ku biramu ebikosa okukuumibwa kwabyo (Pochon ne Jaton, 1967). Okwongera okukola kw’obuwuka obutonotono (metabolism) kw’ebirungo bino kuyinza okukendeeza ku bunywevu bw’enzimba, obulungi bw’okukuuma n’omugaso gw’obuwangwa (Gadd, 2017; Liu et al., 2018). Ku luuyi olulala, mu mbeera ezimu, okukyusakyusa obuwuka obutonotono n’okuddamu ebizimbe bino kizuuliddwa nga kya mugaso kuba bikola ebiwuka ebiramu n’ebikuta ebirala ebikuuma ebikendeeza ku sipiidi y’okuvunda/okuvunda (Martino, 2016). N’olwekyo, okukola enkola ennungi ez’okukuuma ebijjukizo by’amayinja, ebyuma n’embaawo eby’ekiseera ekiwanvu kyetaagisa okutegeera obulungi enkola enkulu ezizingirwa mu nkola eno. Bw’ogeraageranya n’enkola z’obutonde (enkola z’eby’ettaka, omuliro gw’ebibira, okubutuka kw’olusozi, enkolagana y’ebimera ne bakitiriya), emirimu gy’abantu givaamu okufulumya obuzito obunene obwa polycyclic aromatic hydrocarbons (PAHs) ne organic carbon endala (OC) mu nsengekera z’obutonde. PAH nnyingi ezikozesebwa mu bulimi (eddagala eritta ebiwuka n’ebiwuka nga DDT, atrazine, carbaryl, pentachlorophenol, n’ebirala), amakolero (amafuta agatali malongooseemu, ebisasiro by’amafuta/kasasiro, obuveera obuva mu mafuta g’amafuta, PCBs, obuveera, eby’okunaaba, eddagala eritta obuwuka, ebifuuwa omukka, akawoowo n’ebikuuma), ebintu ebikozesebwa mu kwerabirira omuntu (ebiziyiza omusana, ebikuuma omusana ebitta obuwuka, ebigoba ebiwuka n’ebiwuka ebiyitibwa polycyclic musks) n’amasasi (ebitulika nga 2,4,6-TNT) biyinza okukosa obulamu bwa pulaneti (Srogi, 2007; Vamsee-Krishna ne Phale, 2008; Petrie et al., 2015). Olukalala luno luyinza okugaziwa ne luzingiramu ebirungo ebiva mu mafuta g’amafuta (amafuta g’amafuta, ebizigo, asphaltenes), ebiwuka ebiramu ebizitowa molekyu ennene, n’amazzi aga ion (Amde et al., 2015). Omulongooti 1 gulaga obucaafu obw’enjawulo obw’akawoowo n’okukozesebwa kwabwo mu makolero ag’enjawulo. Mu myaka egiyise, omukka ogufuluma mu bantu ogw’ebirungo ebiwunya ebiwunya, awamu ne kaboni dayokisayidi ne ggaasi endala ezikola omukka, bitandise okweyongera (Dvorak et al., 2017). Naye, ebikosa abantu bisukka nnyo eby’obutonde. Okugatta ku ekyo, twakizuula nti SOC eziwerako zisigala mu mbeera nnyingi ez’obutonde era zizuuliddwa ng’obucaafu obuvaayo nga bulina ebikosa ebiramu ku biomes (Ekifaananyi 1). Ebitongole ebivunaanyizibwa ku butonde bw’ensi nga ekitongole kya Amerika ekivunaanyizibwa ku kukuuma obutonde bw’ensi (USEPA) bitadde bingi ku bicaafu bino mu lukalala lwabyo bye bakulembeza olw’obutwa bwabyo obw’obutwa mu bitundu by’omubiri, obutwa mu bitundu by’omubiri, obukyusa obutonde, n’okuleeta kkansa. N’olwekyo, amateeka amakakali agakwata ku kusuula kasasiro n’obukodyo obulungi obw’okulongoosa/okuggya kasasiro mu bitonde ebirimu obucaafu byetaagibwa. Enkola ez’enjawulo ez’okulongoosa mu mubiri n’eddagala nga pyrolysis, oxidative thermal treatment, empewo okufuuwa empewo, okusuula kasasiro, okwokya n’ebirala tezikola era zigula ssente nnyingi era zikola ebivaamu ebivunda, eby’obutwa era ebizibu okujjanjaba. Olw’okumanya okweyongera mu nsi yonna ku butonde bw’ensi, obuwuka obutonotono obusobola okwonoona obucaafu buno n’ebivaamu (nga halogenated, nitro, alkyl ne/oba methyl) bweyongera okusikiriza okufaayo (Fennell et al., 2004; Haritash and Kaushik, 2009; Phale et al., 2020; Sarkar et al., 2020; Schwanemann ne banne, 2020). Okukozesa obuwuka buno obw’enjawulo obw’enjawulo obw’enjawulo bwokka oba mu buwangwa obutabuliddwamu (amatwale) okuggyawo obucaafu obuwunya kulina ebirungi mu by’obukuumi bw’obutonde, omuwendo, obulungi, obulungi, n’okuyimirizaawo. Abanoonyereza era banoonyereza ku kugatta enkola z’obuwuka obutonotono n’enkola za electrochemical redox, kwe kugamba enkola za bioelectrochemical systems (BES), nga tekinologiya asuubiza okulongoosa/okuggyawo obucaafu (Huang et al., 2011). Tekinologiya wa BES ayongedde okusikiriza olw’obulungi bwe obw’amaanyi, ssente entono, obukuumi bw’obutonde, okukola ku bbugumu ly’ekisenge, ebintu ebikwatagana n’ebiramu, n’obusobozi bw’okuzzaawo ebivaamu eby’omuwendo (okugeza, amasannyalaze, amafuta, n’eddagala) (Pant et al., 2012; Nazari et al., 2020). Okujja kw’ebikozesebwa/enkola z’okulonda ensengekera y’obutonde (high-throughput genome sequencing) n’enkola za omics kuwadde amawulire amapya mangi ku kulungamya obuzaale, proteomics, ne fluxomics ez’enkola z’obuwuka obutonotono obw’enjawulo obusaanyawo. Okugatta ebikozesebwa bino n’ebiramu eby’enkola kyongedde okutumbula okutegeera kwaffe ku kulonda n’okulongoosa obulungi amakubo agagendereddwamu aga catabolic mu microorganisms (kwe kugamba, metabolic design) okutuuka ku biodegradation ennungi era ennungi. Okukola enkola ennungi ez’okulongoosa ebiramu nga tukozesa obuwuka obutonotono obusaanira okuvuganya, twetaaga okutegeera obusobozi bw’ebiramu, enjawulo mu nkyukakyuka y’emmere, obutonde bw’obuzaale, n’obutonde (autoecology/synecology) bw’obuwuka obutonotono.
Ekifaananyi 1. Ensibuko n’amakubo ga PAHs eza molekyu entono okuyita mu mbeera ez’enjawulo ez’obutonde n’ensonga ez’enjawulo ezikosa ebiramu. Ennyiriri eziriko enkokola zikiikirira enkolagana wakati w’ebintu by’ensengekera y’obutonde.
Mu kwekenneenya kuno, tugezezzaako okufunza ebikwata ku kuvunda kwa PAHs ennyangu nga naphthalene ne naphthalenes ezikyusiddwa nga zikozesebwa bakitiriya ez’enjawulo ezaawulwamu ezibikka amakubo g’enkyukakyuka y’emmere n’enjawulo, enziyiza ezikwatibwako mu kuvunda, obutonde bw’obuzaale/ebirimu n’enjawulo, okuddamu kw’obutoffaali n’ensonga ez’enjawulo ez’okulongoosa obulamu. Okutegeera emitendera gy’ebiramu ne molekyu kijja kuyamba mu kuzuula ebika by’omugenyi ebisaanira n’okwongera okulongoosa obuzaale bwabyo okusobola okulongoosa obulungi ebiramu eby’obucaafu obw’okukulembeza ng’obwo. Kino kijja kuyamba mu kukola enkola z’okutandikawo ebibiina bya bakitiriya ebikwata ku kifo ekimu okusobola okulongoosa obulungi ebiramu.
Okubeerawo kw’omuwendo omunene ogw’ebirungo ebiwunya eby’obutwa n’eby’obulabe (ebimatiza etteeka lya Huckel 4n + 2π obusannyalazo, n = 1, 2, 3, ...) kuleeta akabi ak’amaanyi eri emikutu egy’enjawulo egy’obutonde ng’empewo, ettaka, ensenke, n’amazzi ag’okungulu n’ag’oku ttaka (Puglisi et al., 2007). Ebirungo bino birina empeta za benzene emu (monocyclic) oba empeta za benzene eziwera (polycyclic) ezitegekeddwa mu ngeri ya linear, angular oba cluster era ziraga obutebenkevu (obutebenkevu/obutabeera mu ntebenkevu) mu butonde olw’amasoboza ga negativu resonance amangi n’obutakola (inertness), ekiyinza okunnyonnyolwa olw’obutabeera bwazo obw’amazzi n’embeera ekendedde. Empeta ey’akawoowo bw’eyongera okukyusibwamu ebibinja bya methyl (-CH3), carboxyl (-COOH), hydroxyl (-OH), oba sulfonate (-HSO3), efuuka ennywevu, eba n’enkolagana ey’amaanyi eri macromolecules, era ebeera ya bioaccumulative mu nkola z’ebiramu (Seo et al., 2009; Phale et al., 2020). Ebimu ku biwunya ebiwunya ebiyitibwa polycyclic aromatic hydrocarbons (LMWAHs), nga naphthalene n’ebivaamu [methylnaphthalene, naphthoic acid, naphthalenesulfonate, ne 1-naphthyl N-methylcarbamate (carbaryl)], bibadde mu lukalala lw’obucaafu obusookerwako obw’obutonde ekitongole kya Amerika ekikuuma obutonde bw’ensi nga genotoxic, ekikyusakyusa, ne/oba ekivaako kkansa (Cerniglia, 1984). Okufulumya ekika kino ekya NM-PAHs mu butonde kiyinza okuvaamu okukuŋŋaanyizibwa kw’ebirungo bino ku mitendera gyonna egy’emmere, bwe kityo ne kikosa obulamu bw’ebitonde (Binkova et al., 2000; Srogi, 2007; Quinn et al., 2009).
Ensibuko n’amakubo ga PAHs okutuuka mu biramu okusinga biyita mu kusenguka n’enkolagana wakati w’ebitundu eby’enjawulo eby’obutonde ng’ettaka, amazzi agali wansi w’ettaka, amazzi ag’okungulu, ebirime n’empewo (Arey ne Atkinson, 2003). Ekifaananyi 1 kiraga enkolagana n’ensaasaanya ya PAH ez’enjawulo ez’obuzito bwa molekyu obutono mu nsengekera z’obutonde n’amakubo gazo okutuuka ku kukwatibwa ebiramu/omuntu. PAHs ziteekebwa ku ngulu nga kiva ku bucaafu bw’empewo era nga ziyita mu kusenguka (drift) kw’omukka ogufuluma mu mmotoka, ggaasi ezifuluma mu makolero (okufuuka ggaasi w’amanda, okwokya n’okukola coke) n’okuteekebwa kwazo. Emirimu gy’amakolero ng’okukola engoye ezikoleddwa mu butonde, langi ne langi; okukuuma enku; okulongoosa emipiira; emirimu gy’okukola seminti; okukola eddagala ly’ebiwuka; n’okukozesebwa mu bulimi bye bisinga okuvaamu PAHs mu nkola z’oku ttaka n’ez’amazzi (Bamforth ne Singleton, 2005; Wick et al., 2011). Okunoonyereza kulaga nti ettaka eriri mu bitundu by’omu bibuga n’ebibuga, okumpi n’enguudo ennene, ne mu bibuga ebinene litera okukwatibwa omukka oguyitibwa polycyclic aromatic hydrocarbons (PAHs) olw’omukka ogufuluma mu mabibiro g’amasannyalaze, ebbugumu ly’amayumba, emigugu gy’entambula y’empewo n’oku nguudo, n’emirimu gy’okuzimba (Suman et al., 2016). (2008) baalaga nti PAHs mu ttaka okumpi n’enguudo mu New Orleans, Louisiana, USA zaali nnyingi nga 7189 μg/kg, so nga mu bifo ebiggule, zaali 2404 μg/kg zokka. Mu ngeri y’emu, emiwendo gya PAH nga 300 μg/kg gibadde gitegeezeddwa mu bitundu ebiriraanye ebifo ebifukibwamu ggaasi amanda mu bibuga bya Amerika ebiwerako (Kanaly ne Harayama, 2000; Bamforth ne Singleton, 2005). Ettaka okuva mu bibuga bya Buyindi eby’enjawulo nga Delhi (Sharma et al., 2008), Agra (Dubey et al., 2014), Mumbai (Kulkarni ne Venkataraman, 2000) ne Visakhapatnam (Kulkarni et al., 2014) ligambibwa nti lirimu ebirungo bya PAHs bingi. Ebirungo ebiwunya byangu okunyigibwa ku butundutundu bw’ettaka, ebiramu n’eby’obugagga eby’omu ttaka eby’ebbumba, bwe bityo ne bifuuka ebifo ebikulu ebinywera kaboni mu nsengekera z’obutonde (Srogi, 2007; Peng et al., 2008). Ensibuko enkulu eza PAHs mu bitonde by’omu mazzi ze nkuba (enkuba ennyogovu/enkalu n’omukka gw’amazzi), amazzi agakulukuta mu bibuga, amazzi amakyafu agakulukuta, okuddamu okujjuza amazzi agali wansi w’ettaka n’ebirala (Srogi, 2007). Kiteeberezebwa nti ebitundu nga 80% ebya PAHs mu bitonde by’ennyanja biva mu nkuba, okutonnya, n’okuyiwa kasasiro (Motelay-Massei et al., 2006; Srogi, 2007). Ebirungo ebingi ebya PAHs mu mazzi ag’okungulu oba amazzi agakulukuta okuva mu bifo omusuulibwa kasasiro omukalu okukkakkana nga gakulukuta mu mazzi agali wansi w’ettaka, ekireeta akabi ak’amaanyi eri obulamu bw’abantu okuva abantu abasukka mu 70% mu South ne Southeast Asia bwe banywa amazzi agali wansi w’ettaka (Duttagupta et al., 2019). Okunoonyereza okwakakolebwa Duttagupta et al. . Enkola z’enkozesa y’ettaka ez’enjawulo n’okweyongera kw’okuggya amazzi wansi w’ettaka bitwalibwa ng’ensonga enkulu ezifuga entambula ey’okwesimbye (advection) eya PAHs ezirina obuzito bwa molekyu obutono mu ttaka. Amazzi agakulukuta mu bulimi, amazzi amakyafu agakulukuta mu munisipaali n’amakolero, n’amazzi amakyafu agakulukuta/kasasiro agakulukuta gazuuliddwa nga bikosebwa PAHs mu bifo by’emigga n’ensenke eziri wansi w’ettaka. Enkuba etonnya mu bbanga eyongera okusajjula obucaafu bwa PAH. Ebirungo ebingi ebya PAHs n’ebivaamu alkyl (51 byonna awamu) bibadde biwandiikiddwa mu migga/ebitundu by’amazzi mu nsi yonna, gamba ng’omugga Fraser, omugga Louan, omugga Denso, omugga Missouri, omugga Anacostia, omugga Ebro, n’omugga Delaware (Yunker et al., 2002; Motelay-Massei et al., 2006; Li et al., 2010; Amoako n’abalala, 2011; Mu nsenke z’omugga Ganges, naphthalene ne phenanthrene bye byazuulibwa nga bye bisinga obukulu (ebyazuulibwa mu sampuli 70%) (Duttagupta et al., 2019). Ekirala, okunoonyereza kulaga nti okussa chlorination mu mazzi ag’okunywa kiyinza okuvaako okutondebwawo kwa PAHs ezisingako obutwa ezirimu oxygen ne chlorinated (Manoli ne Samara, 1999). PAHs zikuŋŋaanyizibwa mu mmere ey’empeke, ebibala n’enva endiirwa nga kiva ku kutwalibwa ebimera okuva mu ttaka eririmu obucaafu, amazzi agali wansi w’ettaka n’enkuba (Fismes et al., 2002). Ebiramu bingi eby’omu mazzi nga ebyennyanja, enseenene, enseenene n’enseenene bifuuse bicaafu ne PAHs nga biyita mu kulya emmere n’amazzi g’ennyanja ebirimu obucaafu, wamu n’okuyita mu bitundu by’omubiri n’olususu (Mackay ne Fraser, 2000). Enkola z’okufumba/okulongoosa nga okusiika, okuyokya, okufuuwa sigala, okusiika, okukala, okufumba n’okufumba mu amanda nazo zisobola okuvaako PAHs nnyingi mu mmere. Kino kisinziira nnyo ku kulonda ekintu ekifuuwa sigala, phenolic/aromatic hydrocarbon content, enkola y’okufumba, ekika kya hhuta, obunnyogovu, oxygen supply n’ebbugumu ly’okwokya (Guillén et al., 2000; Gomes et al., 2013). Polycyclic aromatic hydrocarbons (PAHs) nazo zizuuliddwa mu mata ku bungi obw’enjawulo (0.75–2.1 mg/L) (Girelli et al., 2014). Okukuŋŋaanyizibwa kwa PAHs zino mu mmere nakyo kisinziira ku physicochemical properties y’emmere, so nga obutwa bwazo bukwatagana n’emirimu gy’omubiri, metabolic activity, okunyiga, okusaasaana n’okusaasaana kw’omubiri (Mechini et al., 2011).
Obutwa n’obulabe bwa polycyclic aromatic hydrocarbons (PAHs) bibadde bimanyiddwa okumala ebbanga ddene (Cherniglia, 1984). Low molecular weight polycyclic aromatic hydrocarbons (LMW-PAHs) (empeta bbiri ku ssatu) zisobola okwesiba mu ngeri ya covalent ku macromolecules ez’enjawulo nga DNA, RNA ne proteins era nga zireeta kookolo (Santarelli et al., 2008). Olw’obutonde bwazo obw’amazzi, zaawulwamu obuwuka obuyitibwa lipid membranes. Mu bantu, cytochrome P450 monooxygenases zifuula PAHs oxidize ne zifuuka epoxides, ezimu ku zo zikola nnyo (okugeza, baediol epoxide) era ziyinza okuvaako okukyusa obutoffaali obwa bulijjo okufuuka obubi (Marston et al., 2001). Okugatta ku ekyo, ebiva mu nkyukakyuka ya PAHs nga quinones, phenols, epoxides, diols, n’ebirala biba bya butwa okusinga ebirungo ebizadde. PAHs ezimu n’ebintu byabwe eby’omu makkati mu nkyukakyuka y’emmere bisobola okukosa obusimu n’enziyiza ez’enjawulo mu nkyukakyuka y’emmere, bwe kityo ne bikosa obubi enkula, enkola y’obusimu obw’omu makkati, enkola y’okuzaala n’abaserikale b’omubiri ( Swetha and Phale, 2005 ; Vamsee-Krishna et al., 2006 ; Oostingh et al., 2008 ). Okukwatibwa mu bbanga ettono ku PAHs ezirina molekyu entono kigambibwa nti kireeta okukosa enkola y’amawuggwe n’okuzimba omusaayi mu balwadde ba asima n’okwongera ku bulabe bwa kookolo w’olususu, amawuggwe, ekibumba n’ekyenda (Olsson et al., 2010; Diggs et al., 2011). Okunoonyereza ku bisolo era kulaga nti okukwatibwa PAH kuyinza okuba n’akakwate ku nkola y’okuzaala n’enkula y’omubiri era kuyinza okuleeta okuzimba amaaso, okwonooneka kw’ekibumba n’ekibumba, n’okuzimba ekibumba. Ebintu eby’enjawulo ebikyusa obulamu bwa PAH nga diols, epoxides, quinones ne free radicals (cations) biraze nti bikola DNA adducts. Adducts ezitebenkedde ziragiddwa okukyusa ebyuma ebikoppa DNA, so nga adducts ezitanywevu zisobola okuggya DNA (okusinga okutuuka ku adenine n’oluusi okutuuka ku guanine); byombi bisobola okuleeta ensobi eziviirako enkyukakyuka (Schweigert et al. 2001). Okugatta ku ekyo, quinones (benzo-/pan-) zisobola okukola ebika bya oxygen ebikola (ROS), okuleeta okwonooneka okw’amaanyi ku DNA ne macromolecules endala, bwe kityo ne kikosa enkola y’ebitundu by’omubiri/obulamu (Ewa and Danuta 2017). Okukwatibwa ennyo ebirungo ebitono ebya pyrene, biphenyl ne naphthalene kigambibwa nti kireeta kookolo mu bisolo ebigezesebwa (Diggs et al. 2012). Olw’obutwa bwazo obw’okutta, okuyonja/okuggya PAH zino mu bifo ebikoseddwa/ebifuuse ebicaafu kye kikulu.
Enkola ez’enjawulo ez’obutonde n’eddagala zikozesebwa okuggya PAHs mu bifo/embeera ezirimu obucaafu. Enkola nga okwokya, okuggya chlorination, UV oxidation, fixation, n’okuggyamu solvent zirina ebizibu bingi, omuli okukola ebiva mu butwa, obuzibu bw’enkola, ensonga z’obukuumi n’okulungamya, obulungi obutono, n’omuwendo omunene. Naye, okuvunda kw’obuwuka obutonotono (eyitibwa bioremediation) nkola ndala esuubiza erimu okukozesa obuwuka obutonotono mu ngeri y’obuwangwa obulongoofu oba amakolooni. Bw’ogeraageranya n’enkola ez’omubiri n’ez’eddagala, enkola eno tekola bulabe eri obutonde bw’ensi, teyingirira, tesaasaanya ssente nnyingi, era tesobola kuwangaala. Bioremediation esobola okukolebwa mu kifo ekikoseddwa (in situ) oba mu kifo ekitegekeddwa mu ngeri ey’enjawulo (ex situ) era n’olwekyo etwalibwa ng’enkola ey’okutereeza ewangaala okusinga enkola ez’ekinnansi ez’omubiri n’eddagala (Juhasz ne Naidu, 2000; Andreoni ne Gianfreda, 2007; Megharaj et al., 2011; Phale et al., 2020; Sarkar n’abalala, 2020).
Okutegeera emitendera gy’enkyukakyuka y’obuwuka obutonotono egyenyigira mu kusaanyawo obucaafu obw’akawoowo kirina kinene nnyo kye kikwatako mu bya ssaayansi n’ebyenfuna ku kuyimirizaawo obutonde n’obutonde. Gramu ezibalirirwamu 2.1×1018 eza kaboni (C) ziterekebwa mu nsenke n’ebirungo ebiramu (kwe kugamba, amafuta, ggaasi ow’obutonde, n’amanda, kwe kugamba, amafuta g’ebintu ebikadde) mu nsi yonna, ekiyamba kinene mu nsengekera ya kaboni mu nsi yonna. Naye, okukulaakulana okw’amangu mu makolero, okuggya amafuta g’ebintu ebikadde, n’emirimu gy’abantu bikendeeza ku bifo bino eby’okutereka kaboni ow’amayinja, nga bifulumya 5.5×1015 g za kaboni ow’obutonde (ng’ebicaafu) mu bbanga buli mwaka (Gonzalez-Gaya et al., 2019). Ebisinga ku kaboni ono ow’obutonde biyingira mu nsengekera z’ebitonde eby’oku ttaka n’eby’omu nnyanja nga biyita mu kutonnya, entambula, n’amazzi agakulukuta. Okugatta ku ekyo, obucaafu obupya obw’obutonde obuva mu mafuta g’ebintu ebikadde, gamba ng’obuveera, obuveera n’ebinyweza obuveera (phthalates ne isomers zaabyo), bicaafuwa nnyo mu nnyanja, ettaka n’amazzi n’ebiramu byabwe, bwe kityo ne kyongera obulabe ku mbeera y’obudde mu nsi yonna. Ebika bya microplastics eby’enjawulo, nanoplastics, obuveera obutundutundu n’ebintu byabwe eby’obutwa ebya monomer ebiva mu polyethylene terephthalate (PET) bikuŋŋaanyiziddwa mu Pacific Ocean wakati wa North America ne Southeast Asia, ne bikola “Great Pacific Garbage Patch”, ne bikola obulabe ku bulamu bw’omu nnyanja (Newell et al., 2020). Okunoonyereza kwa ssaayansi kukakasizza nti tekisoboka kuggyawo bucaafu/kasasiro ng’oyo mu nkola yonna ey’omubiri oba ey’eddagala. Mu mbeera eno, obuwuka obutonotono obusinga okuba obw’omugaso bwe buno obusobola okukyusa obucaafu mu ngeri ey’okwokya ne bufuuka kaboni dayokisayidi, amaanyi g’eddagala n’ebintu ebirala ebitali bya butwa ebikkakkana nga biyingidde mu nkola endala ez’enzirukanya y’ebiriisa (H, O, N, S, P, Fe, n’ebirala). Bwe kityo, okutegeera enkola y’obutonde bw’obuwuka obutonotono (microbial ecophysiology) obw’okufuuka eby’obugagga eby’omu ttaka ebicaafu ebiwunya n’okufuga kwabwo obutonde kikulu nnyo mu kwekenneenya enzirukanya ya kaboni y’obuwuka obutonotono, embalirira ya kaboni omutuufu n’obulabe bw’embeera y’obudde mu biseera eby’omu maaso. Okusinziira ku bwetaavu obw’amangu obw’okuggya ebirungo ng’ebyo mu butonde, amakolero ag’enjawulo agakola ku butonde bw’ensi agassa essira ku tekinologiya omuyonjo gazzeewo. Ekirala, okussa omuwendo ku kasasiro w’amakolero/eddagala lya kasasiro erikung’aanyiziddwa mu nsengekera z’obutonde (kwe kugamba enkola ya kasasiro okutuuka ku bugagga) kitwalibwa ng’emu ku mpagi z’ebyenfuna eby’enkulungo n’ebigendererwa by’enkulaakulana ey’olubeerera (Close et al., 2012). N’olwekyo, okutegeera ensonga z’enkyukakyuka mu mubiri, enziyiza n’obuzaale bw’ebintu bino ebiyinza okuvunda kikulu nnyo mu kuggyawo obulungi n’okulongoosa ebiramu eby’obucaafu obw’akawoowo obw’engeri eyo.
Mu bucaafu obungi obw’akawoowo, tufaayo nnyo ku PAH ezirina obuzito bwa molekyu obutono nga naphthalene ne naphthalenes ezikyusiddwa. Ebirungo bino bye bitundu ebikulu eby’amafuta agava mu mafuta g’amafuta, langi z’engoye, ebintu ebikozesebwa, eddagala eritta ebiwuka (ebiwuka ebiwunya n’ebigoba ebiwuka), ebirungo ebikola obuveera n’ebirungo ebiyitibwa tannins era n’olwekyo bibunye nnyo mu nsengekera z’obutonde nnyingi (Preuss et al., 2003). Lipoota ezisembyeyo ziraga okukuŋŋaanyizibwa kw’obungi bwa naphthalene mu nsenke z’amazzi, ettaka eriri wansi w’ettaka n’eri wansi w’ettaka, zoni za vadose n’ebisenge by’emigga, ekiraga okukuŋŋaanyizibwa kwayo okw’ebiramu mu butonde (Duttagupta et al., 2019, 2020). Omulongooti 2 gufunza eby’obutonde, enkozesa n’ebikosa obulamu bwa naphthalene n’ebivaamu. Bw’ogeraageranya ne PAH endala ezirina obuzito bwa molekyu ennene, naphthalene n’ebivaamu tebitera kutabula mazzi, bisaanuuka nnyo mu mazzi era bisaasaanyizibwa nnyo mu nsengekera z’obutonde, kale bitera okukozesebwa ng’ebikozesebwa eby’okulabirako okunoonyereza ku nkyukakyuka y’emmere, obuzaale n’enjawulo y’enkyukakyuka ya PAHs. Omuwendo omunene ogw’obuwuka obutonotono busobola okukyusakyusa naphthalene n’ebivaamu, era amawulire amajjuvu galiwo ku makubo gaabyo ag’okukyusakyusa, enziyiza n’ebintu ebifuga (Mallick et al., 2011; Phale et al., 2019, 2020). Okugatta ku ekyo, naphthalene n’ebivaamu birondeddwa ng’ebirungo ebisookerwako okwekenneenya obucaafu bw’obutonde olw’obungi bwabyo obw’amaanyi n’okubeerawo kw’ebiramu. Ekitongole kya Amerika ekikuuma obutonde bw’ensi kibalirira nti emiwendo gya naphthalene egya wakati giri 5.19 μg buli cubic mita okuva mu mukka gwa sigala, okusinga okuva mu kwokya obutajjuvu, ne 7.8 ku 46 μg okuva mu mukka ogw’oku mabbali, ate ng’okukwatibwa creosote ne naphthalene kusukka emirundi 100 ku 10,000 (Preuss et al. 2003). Naphthalene naddala kizuuliddwa nti alina obutwa mu kussa mu bika, ekitundu, n’ekikula n’okuleeta kookolo. Okusinziira ku kunoonyereza ku bisolo, ekitongole ky’ensi yonna ekinoonyereza ku kookolo (IARC) kyassa eddagala lya naphthalene mu kibinja “ekiyinza okuleeta kookolo w’omuntu” (Group 2B)1. Okukwatibwa naphthalenes ezikyusiddwa, okusinga nga zissa oba nga ziweebwa mu lubuto (mu kamwa), kireeta obuvune mu bitundu by’amawuggwe era kyongera ku bizimba by’amawuggwe mu nvunza n’ebibe (National Toxicology Program 2). Ebivaamu eby’amangu mulimu okuziyira, okusesema, okulumwa olubuto, ekiddukano, okulumwa omutwe, okutabulwa, okutuuyana ennyo, omusujja, tachycardia, n’ebirala Ku luuyi olulala, eddagala eritta ebiwuka erya carbamate erya broad-spectrum carbamate carbaryl (1-naphthyl N-methylcarbamate) libadde ligambibwa okuba ery’obutwa eri ebiramu ebitaliiko mugongo ebiri mu mazzi, emphibians, enjuki z’omubisi gw’enjuki n’... abantu era nga kiragiddwa okuziyiza acetylcholinesterase ekivaako okusannyalala (Smulders et al., 2003; Bulen and Distel, 2011). N’olwekyo, okutegeera enkola z’okuvunda kw’obuwuka obutonotono, okulungamya obuzaale, enkola y’enziyiza n’obutoffaali kikulu nnyo mu kukola enkola z’okulongoosa ebiramu mu mbeera ezirimu obucaafu.
Omulongooti 2. Amawulire mu bujjuvu ku mpisa z’obutonde, enkozesa, enkola z’okuzuula n’endwadde ezikwatagana nazo eza naphthalene n’ebivaamu.
Mu bifo ebicaafu, obucaafu obuwunya obuwunya amazzi n’amasavu busobola okuleeta ebikosa obutoffaali eby’enjawulo ku microbiome y’obutonde (ekitundu), gamba ng’enkyukakyuka mu mazzi g’oluwuzi, okuyita kw’olususu, okuzimba kw’amasavu bilayer, okutaataaganyizibwa kw’okutambuza amasoboza (olujegere lw’entambula y’obusannyalazo/amaanyi agasitula pulotoni), n’emirimu gya puloteyina ezikwatagana n’olususu (Sikkema et al.,, , 1995). Okugatta ku ekyo, ebimu ku bikozesebwa eby’omu makkati ebisaanuuka nga catechols ne quinones bikola ebika bya oxygen ebikola (ROS) ne bikola adducts ne DNA ne proteins (Penning et al., 1999). Bwe kityo, obungi bw’ebirungo ng’ebyo mu nsengekera z’obutonde bussa akazito akalonda ku bitundu by’obuwuka obutonotono okufuuka abasaanyaawo abalungi ku mitendera egy’enjawulo egy’omubiri, omuli okutwala/okutambuza, okukyusa mu butoffaali, okuyingiza/okukozesa, n’okugabanya mu bitundu.
Okunoonyereza mu Ribosomal Database Project-II (RDP-II) kwazuula nti ebika bya bakitiriya 926 byayawulwa okuva mu buwangwa bw’emikutu oba okugaggawaza obucaafu ne naphthalene oba ebivaamu. Ekibinja kya Proteobacteria kye kyasinga okukiikirira (n = 755), ne kiddirirwa Firmicutes (52), Bacteroidetes (43), Actinobacteria (39), Tenericutes (10), ne bacteria ezitasengekeddwa (8) (Ekifaananyi 2). Abakiikiridde γ-Proteobacteria (Pseudomonadales ne Xanthomonadales) be bafuga ebibinja byonna ebya Gram-negative ebirimu G+C omungi (54%), ate Clostridiales ne Bacillales (30%) byali bibinja bya Gram-positive ebirimu G+C entono. Pseudomonas (omuwendo ogusinga obunene, ebika 338) byategeezebwa nti esobola okusaanyawo naphthalene n’ebivaamu methyl mu butonde obw’enjawulo obucaafu (coal tar, petroleum, crude oil, sludge, amafuta agayidde, amazzi amakyafu, kasasiro ow’obutonde n’ebifo ebisuulibwamu kasasiro) awamu ne mu bitonde ebitaliiko kamogo (ettaka, emigga, ensenke n’amazzi agali wansi w’ettaka) . (Ekifaananyi 2). Ekirala, okunoonyereza ku kugaggawaza n’okwekenneenya enkula y’ebimera ebimu ku bitundu bino byalaga nti ebika bya Legionella ne Clostridium ebitakulibwa biyinza okuba n’obusobozi obw’okuvunda, ekiraga obwetaavu bw’okukuza obuwuka buno okunoonyereza ku makubo amapya n’enjawulo mu nkyukakyuka y’emmere.
Ekifaananyi 2. Enjawulo mu nsengeka n’ensaasaanya y’ebitonde ebikiikirira bakitiriya mu mbeera ezirimu ebirungo ebiva mu naphthalene ne naphthalene.
Mu buwuka obw’enjawulo obuwunya obuwunya obusaanya kaboni, obusinga busobola okusaanyaawo naphthalene ng’ensibuko yokka eya kaboni n’amasoboza. Omutendera gw’ebintu ebikwatibwako mu nkyukakyuka ya naphthalene gubadde gunnyonnyolwa ku Pseudomonas sp. (ebika: NCIB 9816-4, G7, AK-5, PMD-1 ne CSV86), Pseudomonas stutzeri AN10, Pseudomonas fluorescens PC20 n’ebika ebirala (ND6 ne AS1) (Mahajan n’abalala, 1994; Resnick n’abalala, 1996; Annweiler n’abalala, 2000; Basu et al., 2003;Dennis ne Zylstra, 2004;Sota et al., 2006; naphthalene okufuuka cis-naphthalenediol (Ekifaananyi 3 Cis-dihydrodiol ekyusibwa okufuuka 1,2-dihydroxynaphthalene nga ekozesebwa dehydrogenase, 1,2-dihydroxynaphthalene dioxygenase (12DHNDO), ekyusa 1,2-dihydroxynaphthalene 2-hydroxychromene-2-carboxylic acid efulumya enzymatic cis-trans isomerization, ekutulwamu hydratase aldolase okufuuka salicylic aldehyde ne pyruvate. NAD+-dependent salicylaldehyde dehydrogenase ekyusa salicylaldehyde okufuuka salicylic acid eyitibwa “ekkubo erya waggulu” ery’okuvunda kwa naphthalene Wabula waliwo ebitonotono ebijjako okugeza, mu thermophilic Bacillus hamburgii 2, naphthalene kitandikibwawo naphthalene 2,3-dioxygenase okukola 2,3-dihydroxynaphthalene (Annweiler et al., 2000).
Ekifaananyi 3. Amakubo g’okuvunda kwa naphthalene, methylnaphthalene, naphthoic acid, ne carbaryl. Ennamba eziriko enzirugavu zikiikirira enziyiza ezivunaanyizibwa ku kukyusa muddiring’anwa kwa naphthalene n’ebivaamu mu bivaamu ebiddako. 1 — ekirungo kya naphthalene dioxygenase (NDO); 2, ekirungo kya cis-dihydrodiol dehydrogenase; 3, 1,2-dihayidirokisinaphthalene dayokisijenaasi; 4, 2-hayidirokisikiromini-2-kabokisiliki asidi isomerase; 5, trans-O-hayidirokisibenzilidenepiruvate hydratase aldolase; 6, eddagala lya salicylaldehyde dehydrogenase; 7, ekirungo kya salicylate 1-hydroxylase; 8, katekol 2,3-dayokisijenaasi (C23DO); 9, 2-hydroxymuconate semialdehayidi dehayidirojenaasi; 10, 2-oksopent-4-enoate eddagala eriyitibwa hydratase; 11, 4-hayidirokisi-2-oksopentanoate aldolase; 12, asetaldehayidi dehydrogenase; 13, katekol-1,2-dayokisijenaasi (C12DO); 14, ekirungo kya muconate cycloisomerase; 15, ekirungo kya muconolactone delta-isomerase; 16, β-ketoadipatenollactone eddagala eriyitibwa amazzi; 17, β-ketoadipate succinyl-CoA okutambuza eddagala eriyitibwa β-ketoadipate; 18, β-ketoadipate-CoA thiolase, eddagala eriyitibwa β-ketoadipate-CoA thiolase; 19, sukisini-CoA: aseeti-CoA sukisinilitransferasi; 20, ekirungo kya salicylate 5-hydroxylase; 21 – ekirungo kya gentisate 1,2-dioxygenase (GDO); 22, ekirungo kya maleylpyruvate isomerase; 23, eddagala eriyitibwa fumarylpyruvate hydrolase; 24, ekirungo kya methylnaphthalene hydroxylase (NDO); 25, ekirungo kya haidrokisimethylnaphthalene dehydrogenase; 26, ekirungo kya naphthaldehyde dehydrogenase; 27, asidi wa 3-formylsalicylic oksidaasi; 28, haidroksiisophthalate dekabokisilaasi; 29, kaaburili hayidirolaasi (CH); 30, 1-naphthol-2-hayidiroksilaasi.
Okusinziira ku kiramu n’obutonde bwakyo, asidi wa salicylic avaamu ayongera okukyusibwa oba okuyita mu kkubo lya catechol nga tukozesa salicylate 1-hydroxylase (S1H) oba okuyita mu kkubo lya gentisate nga tukozesa salicylate 5-hydroxylase (S5H) (Ekifaananyi 3). Okuva asidi wa salicylic bwe kiri ekintu ekikulu eky’omu makkati mu nkyukakyuka ya naphthalene (ekkubo erya waggulu), emitendera okuva ku asidi wa salicylic okutuuka mu makkati ga TCA gitera okuyitibwa ekkubo erya wansi, era obuzaale busengekebwa mu operon emu. Kya bulijjo okulaba nti obuzaale mu operon y’ekkubo erya waggulu (nah) ne operon y’ekkubo erya wansi (sal) bufugibwa ensonga ezifuga eza bulijjo; okugeza, NahR ne salicylic acid bikola nga inducers, okusobozesa operons zombi okukyusakyusa ddala naphthalene (Phale et al., 2019, 2020).
Okugatta ku ekyo, catechol ekutulwamu mu ngeri ey’enzirukanya okutuuka ku 2-hydroxymuconate semialdehyde ng’eyita mu kkubo lya meta nga catechol 2,3-dioxygenase (C23DO) (Yen et al., 1988) era n’eyongera okusaanuusibwa amazzi ne 2-hydroxymuconate semialdehyde hydrolase okukola 2-hydroxypent-2,4-dienoic acid. Olwo 2-hydroxypent-2,4-dienoate ekyusibwa okufuuka pyruvate ne acetaldehyde nga ekozesebwa hydratase (2-oxopent-4-enoate hydratase) ne aldolase (4-hydroxy-2-oxopentanoate aldolase) n’oluvannyuma n’eyingira mu kkubo lya kaboni erya wakati (Figure 3). Ekirala, catechol ekutulwa mu ngeri ey’enzirukanya okutuuka ku cis,cis-muconate ng’eyita mu kkubo lya ortho nga eyita mu catechol 1,2-oxygenase (C12DO). Muconate cycloisomerase, muconolactone isomerase, ne β-ketoadipate-nollactone hydrolase bikyusa cis,cis-muconate okufuuka 3-oxoadipate, ekiyingira mu kkubo lya kaboni erya wakati nga kiyita mu succinyl-CoA ne acetyl-CoA (Nozaki et al., 1968) (Ekifaananyi 3).
Mu kkubo lya gentisate (2,5-dihydroxybenzoate), empeta ey’akawoowo ekutulwamu gentisate 1,2-dioxygenase (GDO) okukola maleylpyruvate. Ekintu kino kiyinza okufuulibwa amazzi butereevu ne kifuuka pyruvate ne malate, oba kiyinza okufuulibwa isomerized ne kikola fumarylpyruvate, oluvannyuma ne kifuulibwa amazzi ne kifuuka pyruvate ne fumarate (Larkin ne Day, 1986). Okulonda ekkubo eddala kulabiddwa mu bakitiriya zombi eza Gram-negative ne Gram-positive ku mutendera gw’ebiramu n’obuzaale (Morawski et al., 1997; Whyte et al., 1997). Bakitiriya aba Gram-negative (Pseudomonas) basinga kwagala kukozesa asidi wa salicylic, nga kino kye kivaako okukyusakyusa naphthalene, ne kigiggyamu kabokisi okutuuka ku catechol nga bakozesa salicylate 1-hydroxylase (Gibson ne Subramanian, 1984). Ku luuyi olulala, mu bakitiriya Gram-positive (Rhodococcus), salicylate 5-hydroxylase ekyusa salicylic acid okufuuka gentisic acid, so nga salicylic acid talina inductive effect ku inductive effect ku transcription ya naphthalene genes (Grund et al., 1992) (Figure 3).
Kigambibwa nti ebika nga Pseudomonas CSV86, Oceanobacterium NCE312, Marinhomonas naphthotrophicus, Sphingomonas paucimobilis 2322, Vibrio cyclotrophus, Pseudomonas fluorescens LP6a, Pseudomonas ne Mycobacterium ebika bisobola okusaanyawo monomethylnaphthalene oba dimethylnaphthalene (Dean-Raymond ne Bartha, 1975; Cane ne Williams, 1982; Mahajan n’abalala, 1994; Dutta n’abalala, 1998; Hedlund n’abalala, 1999). Mu byo, ekkubo ly’okuvunda erya 1-methylnaphthalene ne 2-methylnaphthalene erya Pseudomonas sp. CSV86 ebadde esomeseddwa bulungi ku mitendera gy’ebiramu n’enziyiza (Mahajan et al., 1994). 1-Methylnaphthalene akyusibwa okuyita mu makubo abiri. Okusooka, empeta ey’akawoowo efuulibwa hydroxylated (empeta ya methylnaphthalene etakyusiddwa) okukola cis-1,2-dihydroxy-1,2-dihydro-8-methylnaphthalene, eyongera okufuuka oxidized okufuuka methyl salicylate ne methylcatechol, n’oluvannyuma n’eyingira mu kkubo lya kaboni erya wakati oluvannyuma lw’okukutuka kw’empeta (Ekifaananyi 3). Ekkubo lino liyitibwa “ekkubo ly’ensibuko ya kaboni”. Mu “kkubo ly’okuggya obutwa” ery’okubiri, ekibinja kya methyl kiyinza okufuulibwa hydroxylated ne NDO okukola 1-hydroxymethylnaphthalene, eyongera okufuuka oxidized ne kifuuka 1-naphthoic acid ne kifulumizibwa mu culture medium nga ekintu ekifu. Okunoonyereza kulaga nti ekika kya CSV86 tekisobola kukula ku 1- ne 2-naphthoic acid nga ensibuko yokka eya kaboni n’amasoboza, ekikakasa ekkubo lyayo ery’okuggya obutwa mu mubiri (Mahajan et al., 1994; Basu et al., 2003). Mu 2-methylnaphthalene, ekibinja kya methyl kiyita mu hydroxylation nga hydroxylase ekola 2-hydroxymethylnaphthalene. Okugatta ku ekyo, empeta etakyusiddwa ey’empeta ya naphthalene eyita mu ring hydroxylation okukola dihydrodiol, efuuka oxidized okutuuka ku 4-hydroxymethylcatechol mu lunyiriri lw’ensengekera eziyitibwa enzyme-catalyzed reactions era n’eyingira mu kkubo lya kaboni ery’omu makkati ng’eyita mu kkubo ly’okukutula kw’empeta ya meta. Mu ngeri y’emu, S. paucimobilis 2322 yategeezebwa nti ekozesa NDO okukola hydroxylate 2-methylnaphthalene, eyongera okufuuka oxidized okukola methyl salicylate ne methylcatechol (Dutta et al., 1998).
Asidi za naphthoic (ezikyusiddwa/ezitakyusiddwa) biva mu kuggya obutwa/okukyusa obulamu ebikolebwa mu kiseera ky’okuvunda kwa methylnaphthalene, phenanthrene ne anthracene ne bifulumizibwa mu kifo eky’okukuza ekikozesebwa. Kigambibwa nti ekirungo ekyawuddwa mu ttaka ekya Stenotrophomonas maltophilia CSV89 kisobola okukyusakyusa asidi wa 1-naphthoic ng’ensibuko ya kaboni (Phale et al., 1995). Enkyukakyuka y’ebirungo etandika n’okufuuka dihydroxylation y’empeta ey’akawoowo okukola 1,2-dihydroxy-8-carboxynaphthalene. Diol evuddemu efuuka oxidized okufuuka catechol nga eyitira mu 2-hydroxy-3-carboxybenzylidenepyruvate, 3-formylsalicylic acid, 2-hydroxyisophthalic acid ne salicylic acid era n’eyingira mu kkubo lya kaboni erya wakati ng’eyita mu kkubo ly’okukutula kwa meta-ring (Figure 3).
Carbaryl ddagala eriweweeza ku biwuka erya naphthyl carbamate. Okuva mu nkyukakyuka ya Green Revolution mu Buyindi mu myaka gya 1970, okukozesa ebigimusa eby’eddagala n’eddagala ly’ebiwuka kivuddeko okweyongera kw’omukka ogufuluma mu by’obulimi (Pingali, 2012; Duttagupta et al., 2020). Ebitundu ebibalirirwamu ebitundu 55% (hectares 85,722,000) ku ttaka lyonna ery’ebirime mu Buyindi lirongooseddwa n’eddagala eritta ebiwuka. Mu myaka etaano egiyise (2015–2020), ekitongole ky’ebyobulimi mu Buyindi kikozesezza ttani z’eddagala eritta ebiwuka ku kigero kya wakati wa ttani 55,000 ku 60,000 buli mwaka (Department of Cooperatives and Farmers Welfare, Ministry of Agriculture, Government of India, August 2020). Mu biwonvu bya Gangetic eby’obukiikakkono n’amasekkati (amasaza agasingamu abantu abangi n’abantu abangi), okukozesa eddagala ly’ebiwuka ku birime kusaasaanidde nnyo, ng’eddagala eritta ebiwuka lye lisinga. Carbaryl (1-naphthyl-N-methylcarbamate) ddagala eriweweeza ku biwuka erya carbamate eririmu obutwa obugazi, ery’obutwa obw’ekigero okutuuka ku bungi erikozesebwa mu bulimi bwa Buyindi ku kigero kya wakati ekya ttani 100–110. Kitera okutundibwa wansi w’erinnya ly’obusuubuzi erya Sevin era nga kikozesebwa okulwanyisa ebiwuka (enseke, enseenene z’omuliro, enseenene, enkwale, enkonge n’ebiwuka ebirala bingi eby’ebweru) ebikosa ebirime eby’enjawulo (emmwaanyi, amajaani, ppamba, ebibala n’enva endiirwa). Ebiwuka ebimu ebitonotono nga Pseudomonas (NCIB 12042, 12043, C4, C5, C6, C7, Pseudomonas putida XWY-1), Rhodococcus (NCIB 12038), Sphingobacterium spp. (CF06), Burkholderia (C3), Micrococcus ne Arthrobacter nabyo bisobola okukozesebwa okulwanyisa ebiwuka ebirala. Kigambibwa nti RC100 esobola okusaanyawo carbaryl (Larkin ne Day, 1986; Chapalamadugu ne Chaudhry, 1991; Hayatsu et al., 1999; Swetha ne Phale, 2005; Trivedi et al., 2017). Ekkubo ly’okuvunda kwa carbaryl lisomeseddwa nnyo ku mitendera gy’ebiramu, enziyiza n’obuzaale mu bitundu by’ettaka ebyawuddwamu ebya Pseudomonas sp. Ebika bya C4, C5 ne C6 (Swetha ne Phale, 2005; Trivedi et al., 2016) (Ekifaananyi 3). Ekkubo ly’enkyukakyuka y’emmere litandika n’okusengejja amazzi kw’ekiyungo kya ester nga kikolebwa carbaryl hydrolase (CH) okukola 1-naphthol, methylamine ne carbon dioxide. Olwo 1-naphthol ekyusibwa okufuuka 1,2-dihydroxynaphthalene nga 1-naphthol hydroxylase (1-NH), eyongera okukyusibwa okuyita mu kkubo lya kaboni erya wakati okuyita mu salicylate ne gentisate. Bakitiriya ezimu ezisaanyaawo carbaryl zigambibwa nti zigikyusa n’efuuka asidi wa salicylic nga ziyita mu kukutula empeta ya catechol ortho (Larkin ne Day, 1986; Chapalamadugu ne Chaudhry, 1991). Ekikulu, obuwuka obusaanyawo naphthalene okusinga bukyusa asidi wa salicylic nga buyita mu catechol, so nga bakitiriya ezisaanyaawo carbaryl zisinga kwagala okukyusa asidi wa salicylic nga ziyita mu kkubo lya gentisate.
Naphthalenesulfonic acid/disulfonic acid ne naphthylaminesulfonic acid derivatives zisobola okukozesebwa nga intermediates mu kukola azo dyes, wetting agents, dispersants, etc. Wadde nga ebirungo bino birina obutwa obutono eri abantu, okwekenneenya obutwa mu cytotoxicity kulaga nti bitta ebyennyanja, daphnia ne algae (Greim et al., 1994). Abakiikiridde ekika kya Pseudomonas (ebika A3, C22) kigambibwa nti batandikawo enkyukakyuka mu mubiri nga bakozesa okukyusakyusa emirundi ebiri mu mpeta ey’akawoowo erimu ekibinja kya asidi wa sulfonic okukola dihydrodiol, eyongera okukyusibwa okufuuka 1,2-dihydroxynaphthalene nga basala ekibinja kya sulfite mu ngeri ey’okwekolako (Brilon et al., 1981). Ekivaamu 1,2-dihydroxynaphthalene kikyusibwa okuyita mu kkubo lya naphthalene erya kikula, kwe kugamba, ekkubo lya catechol oba gentisate (Ekifaananyi 4). Kizuuliddwa nti asidi aminophthalenesulfonic ne asidi wa hydroxynaphthalenesulfonic bisobola okusaanawo ddala nga bikozesebwa ebibiina bya bakitiriya ebitabuddwamu nga balina amakubo ga catabolic agajjuliza (Nortemann et al., 1986). Kizuuliddwa nti omu ku bammemba b’ekibiina kino aggyamu asidi wa aminonaphthalenesulfonic oba asidi wa hydroxynaphthalenesulfonic nga akozesa 1,2-dioxygenation, ate aminosalicylate oba hydroxysalicylate efulumizibwa mu kifo awakuzibwa ng’ekirungo ekifu era oluvannyuma ne kitwalibwa bammemba abalala ab’ekibiina. Asidi wa naphthalenedisulfonic abeera wa polar naye nga tavunda bulungi era n’olwekyo asobola okukyusibwamu ng’ayita mu makubo ag’enjawulo. Okuggya ekibiriiti okusooka kubaawo mu kiseera ky’okusengejja dihydroxylation (regioselective dihydroxylation) y’empeta ey’akawoowo n’ekibinja kya asidi wa sulfonic; okuggyibwako ekibiriiti okw’okubiri kubaawo mu kiseera ky’okufuula asidi 5-sulfosalicylic hydroxylation nga salicylic acid 5-hydroxylase okukola asidi wa gentisic, ayingira mu kkubo lya kaboni erya wakati (Brilon et al., 1981) (Ekifaananyi 4). Enziyiza ezivunaanyizibwa ku kuvunda kwa naphthalene nazo zivunaanyizibwa ku nkyukakyuka ya naphthalene sulfonate (Brilon et al., 1981; Keck et al., 2006).
Ekifaananyi 4. Amakubo g’enkyukakyuka y’ebirungo mu kuvunda kwa naphthalene sulfonate. Ennamba eziri munda mu nkulungo zikiikirira enziyiza ezivunaanyizibwa ku nkyukakyuka ya naphthyl sulfonate, ezifaanagana/ezifaanagana n’enziyiza eziragiddwa mu kifaananyi. 3. 3. .
PAHs ez’obuzito bwa molekyu obutono (LMW-PAHs) zikendeezebwa, teziyingira mazzi era tezisaanuuka bulungi, n’olwekyo tezitera kumenya/kuvunda mu butonde. Naye obuwuka obutonotono obukola omukka busobola okugifuula oxidation nga bunyiga molekyu oxygen (O2). Enziyiza zino okusinga ziri mu kiraasi ya oxidoreductases era zisobola okukola ensengekera ez’enjawulo nga aromatic ring hydroxylation (mono- oba dihydroxylation), dehydrogenation ne aromatic ring cleavage. Ebintu ebifunibwa okuva mu nsengekera zino biri mu mbeera ya oxidation eya waggulu era byangu okukyusibwa okuyita mu kkubo lya kaboni erya wakati (Phale et al., 2020). Enziyiza eziri mu kkubo ly’okuvunda kigambibwa nti ziyinza okuleetebwa. Omulimu gwa enziyiza zino guba mutono nnyo oba tegufaayo nnyo ng’obutoffaali bukuliddwa ku nsibuko za kaboni ennyangu nga glucose oba organic acids. Omulongooti 3 gufunza enziyiza ez’enjawulo (oxygenases, hydrolases, dehydrogenases, oxidases, n’ebirala) ezikwatibwako mu nkyukakyuka ya naphthalene n’ebivaamu.
Omulongooti 3. Ebifaananyi by’ebiramu eby’enziyiza ezivunaanyizibwa ku kuvunda kwa naphthalene n’ebivaamu.
Okunoonyereza ku radioisotope (18O2) kulaga nti okuyingiza molekyu O2 mu mpeta ez’akawoowo nga oxygenases ze ddaala erisinga obukulu mu kukola okwongera okuvunda kw’ebiramu mu kirungo (Hayaishi et al., 1955; Mason et al., 1955). Okuyingiza atomu emu eya okisigyeni (O) okuva mu molekyu ya okisigyeni (O2) mu substrate kutandikibwawo oba monooxygenases ez’omunda oba ez’ebweru (era eziyitibwa hydroxylases). Atomu endala eya okisigyeni ekendeezebwa n’efuuka amazzi. Exogenous monooxygenases zikendeeza ku flavin ne NADH oba NADPH, so nga mu endomonooxygenases flavin ekendeezebwa substrate. Ekifo kya hydroxylation kivaamu enjawulo mu kutondebwa kw’ebintu. Okugeza, salicylate 1-hydroxylase ekola hydroxylates salicylic acid mu kifo kya C1, ne kikola catechol. Ku luuyi olulala, ekitundu ekinene ekya salicylate 5-hydroxylase (ekirimu reductase, ferredoxin, ne oxygenase subunits) kikola hydroxylates salicylic acid mu kifo kya C5, ne kikola asidi wa gentisic (Yamamoto et al., 1965).
Dioxygenases ziyingiza atomu za O2 bbiri mu substrate. Okusinziira ku bikozesebwa ebikolebwa, byawulwamu mu ring hydroxylating dioxygenases ne ring cleaving dioxygenases. Ring hydroxylating dioxygenases zikyusa substrates eziwunya okufuuka cis-dihydrodiols (okugeza, naphthalene) era zisaasaanidde nnyo mu bakitiriya. N’okutuusa kati, kiragiddwa nti ebiramu ebirimu ring hydroxylating dioxygenases bisobola okukula ku nsibuko za kaboni ez’akawoowo ez’enjawulo, era enziyiza zino zigabanyizibwamu nga NDO (naphthalene), toluene dioxygenase (TDO, toluene), ne biphenyl dioxygenase (BPDO, biphenyl). NDO ne BPDO zombi zisobola okutandikawo okuwunyiriza okw’emirundi ebiri n’okufuuka hydroxylation ey’olujegere olw’ebbali (side chain hydroxylation) ya kaboni ez’enjawulo eziwunya obulungi (toluene, nitrotoluene, xylene, ethylbenzene, naphthalene, biphenyl, fluorene, indole, methylnaphthalene, naphthalenesulfonate, phenanthrene, anthracene, acetophenone, n’ebirala). (Boyd ne Sheldrake, 1998; Phale n’abalala, 2020). NDO nkola ya bitundu bingi erimu oxidoreductase, ferredoxin, n’ekitundu ekikola ekya oxygenase ekirimu ekifo (Gibson and Subramanian, 1984; Resnick et al., 1996). Ekitundu ekitabula ekya NDO kirimu ekitundu ekinene ekya α n’ekitundu ekitono ekya β ekitegekeddwa mu nsengekera ya α3β3. NDO eri mu famire ennene eya oxygenases era α-subunit yaayo erimu ekifo kya Rieske [2Fe-2S] n’ekyuma ekitali kya heme ekya mononuclear, ekisalawo substrate specificity ya NDO (Parales et al., 1998). Mu ngeri entuufu, mu nsengekera emu ey’okutabula, obusannyalazo bubiri okuva mu kukendeeza kwa nyukiliyotayidi ya piridini bukyusibwa okudda mu ion ya Fe(II) mu kifo ekikola nga buyita mu kifo kya reductase, ferredoxin n’ekifo kya Rieske. Ebigerageranyo ebikendeeza bikola okisigyeni wa molekyu, nga kino kyetaagisa okusooka okukola substrate dihydroxylation (Ferraro et al., 2005). N’okutuusa kati, NDO ntono zokka ze zirongooseddwa era ne zimanyiddwa mu bujjuvu okuva mu bika eby’enjawulo era okufuga obuzaale bw’amakubo agakwatibwako mu kuvunda kwa naphthalene kusomeseddwa mu bujjuvu (Resnick et al., 1996; Parales et al., 1998; Karlsson et al., 2003). Dioxygenases ezikutula empeta (enzymes ezikutula endo- oba ortho-ring ne enzymes ezikutula empeta exodiol- oba meta-ring) zikola ku bikozesebwa ebiwunya ebirimu hydroxylated. Okugeza, dioxygenase ekutula ortho-ring ye catechol-1,2-dioxygenase, so nga dioxygenase esala empeta ya meta ye catechol-2,3-dioxygenase (Kojima et al., 1961; Nozaki et al., 1968). Ng’oggyeeko oxygenases ez’enjawulo, waliwo ne dehydrogenases ez’enjawulo ezivunaanyizibwa ku kuggya amazzi mu dihydrodiols eziwunya, omwenge ne aldehydes n’okukozesa NAD+/NADP+ nga electron acceptors, nga zino ze zimu ku enzymes enkulu ezikwatibwako mu metabolism (Gibson and Subramanian, 1984; Shaw and Harayama, 1990; Fahle et al., 2020).
Enziyiza nga hydrolases (esterases, amidases) ye kiraasi eyokubiri enkulu eya enzymes ezikozesa amazzi okukutula covalent bonds era nga ziraga broad substrate specificity. Carbaryl hydrolase ne hydrolases endala zitwalibwa ng’ebitundu bya periplasm (transmembrane) mu bammemba ba bakitiriya ba Gram-negative (Kamini et al., 2018). Carbaryl alina ekiyungo kya amide ne ester; n’olwekyo, esobola okufuuka amazzi oba esterase oba amidase okukola 1-naphthol. Carbaryl mu kika kya Rhizobium rhizobium AC10023 ne Arthrobacter ekika kya RC100 kigambibwa nti ekola nga esterase ne amidase. Carbaryl mu kika kya Arthrobacter RC100 nayo ekola nga amidase. RC100 eragiddwa okusengejja eddagala ly’ebiwuka nnya erya N-methylcarbamate class nga carbaryl, methomyl, mefenamic acid ne XMC (Hayaatsu et al., 2001). Kyategeezeddwa nti CH mu Pseudomonas sp. C5pp esobola okukola ku carbaryl (100% activity) ne 1-naphthyl acetate (36% activity), naye si ku 1-naphthylacetamide, ekiraga nti ye esterase (Trivedi et al., 2016).
Okunoonyereza ku biramu, enkola y’okulungamya enziyiza, n’okwekenneenya obuzaale biraga nti obuzaale bw’okuvunda kwa naphthalene bubaamu ebitundu bibiri ebifuga ebiyinza okuleetebwa oba “operons”: nah (“ekkubo erya waggulu”, erikyusa naphthalene okufuuka asidi wa salicylic) ne sal (“ekkubo erya wansi”, okukyusa asidi wa salicylic okudda mu kkubo lya kaboni erya wakati nga liyita mu catechol). Salicylic acid ne analogues ze zisobola okukola nga inducers (Shamsuzzaman ne Barnsley, 1974). Mu kubeerawo kwa glucose oba organic acids, operon enyigirizibwa. Ekifaananyi 5 kiraga ensengeka y’obuzaale enzijuvu ey’okuvunda kwa naphthalene (mu ngeri ya operon). Enjawulo/engeri eziwerako ezituumiddwa amannya ez’obuzaale bwa nah (ndo/pah/dox) zitegeezeddwa era ne zizuulibwa nga zirina enkolagana ey’omutendera ey’amaanyi (90%) mu bika byonna ebya Pseudomonas (Abbasian et al., 2016). Okutwalira awamu obuzaale bw’ekkubo lya naphthalene upstream okutwalira awamu bwasengekebwa mu nsengeka y’okukkaanya nga bwe kiragibwa mu kifaananyi 5A. Ensengekera endala, nahQ, nayo yategeezebwa nti yeenyigira mu nkyukakyuka ya naphthalene era nga etera okubeera wakati wa nahC ne nahE, naye omulimu gwayo gwennyini gukyalina okunnyonnyolwa. Mu ngeri y’emu, ensengekera ya nahY, evunaanyizibwa ku naphthalene-sensitive chemotaxis, yasangibwa ku nkomerero ey’ewala eya nah operon mu bammemba abamu. Mu Ralstonia sp., U2 gene encoding glutathione S-transferase (gsh) yazuulibwa nga eri wakati wa nahAa ne nahAb naye teyakosa mpisa za nkozesa ya naphthalene (Zylstra et al., 1997).
Ekifaananyi 5. Ensengeka y’obuzaale n’enjawulo etunuuliddwa mu kiseera ky’okuvunda kwa naphthalene mu bika bya bakitiriya; (A) Ekkubo lya naphthalene erya waggulu, okukyusakyusa naphthalene okufuuka asidi wa salicylic; (B) Ekkubo lya naphthalene erya wansi, asidi wa salicylic ng’ayita mu catechol okutuuka mu kkubo lya kaboni erya wakati; (C) asidi wa salicylic ng’ayita mu gentisate okutuuka mu kkubo lya kaboni erya wakati.
“Ekkubo erya wansi” (sal operon) litera okubaamu nahGTHINLMOKJ era likyusa salicylate okufuuka pyruvate ne acetaldehyde nga liyita mu kkubo lya catechol metaring cleavage. Ensengekera ya nahG (encoding salicylate hydroxylase) yasangibwa nga ekuumibwa ku nkomerero y’okumpi eya operon (Fig. 5B). Bw’ogeraageranya n’ebika ebirala ebivunda naphthalene, mu P. putida CSV86 operons za nah ne sal zikwatagana era zikwatagana nnyo (nga 7.5 kb). Mu bakitiriya abamu aba Gram-negative, nga Ralstonia sp. U2, Polaromonas naphthalenivorans CJ2, ne P. putida AK5, naphthalene ekyusibwa nga ekirungo kya kaboni ekiri wakati nga kiyita mu kkubo lya gentisate (mu ngeri ya sgp/nag operon). Kaseti y’obuzaale etera okulagibwa mu ngeri nagAaGHAbAcAdBFCQEDJI, nga nagR (ewandiika enkodi y’ekirungo ekitereeza ekika kya LysR) esangibwa ku nkomerero eya waggulu (Ekifaananyi 5C).
Carbaryl ayingira mu nsengekera ya kaboni ey’omu makkati ng’ayita mu nkyukakyuka ya 1-naphthol, 1,2-dihydroxynaphthalene, salicylic acid, ne gentisic acid (Ekifaananyi 3). Okusinziira ku kunoonyereza ku buzaale n’enkyukakyuka y’emmere, kiteeseddwa okugabanyaamu ekkubo lino mu “waggulu” (okukyusa carbaryl okudda mu salicylic acid), “wakati” (okukyusa salicylic acid okudda mu gentisic acid), ne “downstream” (okukyusa asidi gentisic okudda mu central carbon pathway intermediates) (Singh et al., 2013). Okwekenenya ensengekera y’obutonde (genomic analysis) kwa C5pp (supercontig A, 76.3 kb) kwalaga nti ensengekera ya mcbACBDEF yeenyigira mu kukyusa carbaryl okufuuka salicylic acid, n’eddirirwa mcbIJKL mu kukyusa salicylic acid okufuuka gentisic acid, ne mcbOQP mu kukyusa gentisic acid okufuuka central carbon intermediates (fumarate ne pyruvate, Trivedi et al., 2016) (Ekifaananyi 6).
Kigambibwa nti enziyiza ezenyigira mu kuvunda kwa hydrocarbons eziwunya (omuli naphthalene ne salicylic acid) zisobola okuleetebwa ebirungo ebikwatagana ne ziziyizibwa ensibuko za kaboni ennyangu nga glucose oba organic acids (Shingler, 2003; Phale et al., 2019, 2020). Mu makubo ag’enjawulo ag’okukyusakyusa ebiriisa mu mubiri (metabolic pathways) aga naphthalene n’ebivaamu, ebifaananyi ebifuga naphthalene ne carbaryl bibadde bisomesebwa okutuuka ku ddaala eritali limu. Ku naphthalene, obuzaale mu makubo gombi ag’okungulu n’aga wansi bufugibwa NahR, LysR-type trans-acting positive regulator. Kyetaagisa okuyingiza obuzaale bwa nah nga asidi wa salicylic n’okulaga kwayo okw’omutindo ogwa waggulu okuddirira (Yen ne Gunsalus, 1982). Ekirala, okunoonyereza kulaga nti integrative host factor (IHF) ne XylR (sigma 54-dependent transcriptional regulator) nabyo bikulu nnyo mu kukola okuwandiika kw’obuzaale mu nkyukakyuka ya naphthalene (Ramos et al., 1997). Okunoonyereza kulaga nti enziyiza z’ekkubo eriggulawo empeta ya catechol, kwe kugamba catechol 2,3-dioxygenase, ziyingizibwa mu kubeerawo kwa naphthalene ne/oba salicylic acid (Basu et al., 2006). Okunoonyereza kulaga nti enziyiza z’ekkubo eriggulawo empeta ya catechol ortho-ring, kwe kugamba catechol 1,2-dioxygenase, ziyingizibwa mu kubeerawo kwa asidi wa benzoic ne cis,cis-muconate (Parsek et al., 1994; Tover et al., 2001).
Mu kika kya C5pp, obuzaale butaano, mcbG, mcbH, mcbN, mcbR ne mcbS, buwandiika ebifuga ebibeera mu famire ya LysR/TetR ey’ebifuga okuwandiika ebivunaanyizibwa ku kufuga okuvunda kwa carbaryl. Ensengekera y’obutonde (homologous gene mcbG) yazuulibwa nga esinga kukwatagana nnyo n’ekirungo ekifuga ekika kya LysR PhnS (58% amino acid identity) eyenyigira mu nkyukakyuka ya phenanthrene mu Burkholderia RP00725 (Trivedi et al., 2016). Ensengekera ya mcbH yazuulibwa nga yeenyigira mu kkubo ery’omu makkati (okukyusa asidi wa salicylic okudda mu asidi wa gentisic) era nga ya LysR-type transcriptional regulator NagR/DntR/NahR mu Pseudomonas ne Burkholderia. Abantu b’omu maka gano baaloopebwa okutegeera asidi wa salicylic nga molekyu y’ekola (specific effector molecule) ey’okuyingiza obuzaale obuvunda. Ku luuyi olulala, obuzaale busatu, mcbN, mcbR ne mcbS, obwa LysR ne TetR type transcriptional regulators, bwazuulibwa mu kkubo eriri wansi (gentisate-central carbon pathway metabolites).
Mu prokaryotes, enkola z’okutambuza obuzaale mu bbanga (okufuna, okuwanyisiganya, oba okukyusa) okuyita mu plasmids, transposons, prophages, genomic islands, ne integrative conjugative elements (ICE) bye bikulu ebivaako obuveera mu genomes za bakitiriya, ekivaako okufuna oba okufiirwa emirimu/engeri ezenjawulo. Kisobozesa obuwuka okukyusa amangu embeera z’obutonde ez’enjawulo, ne kiwa enkizo eziyinza okukwatagana mu nkyukakyuka y’emmere eri omugenyi, gamba ng’okuvunda kw’ebirungo ebiwunya. Enkyukakyuka mu mubiri zitera okutuukibwako nga tuyita mu kulongoosa obulungi operons ezivunda, enkola zazo ezifuga, n’obutonde bw’enziyiza, ekyanguyiza okuvunda kw’ebirungo ebiwunya ebingi (Nojiri et al., 2004; Phale et al., 2019, 2020). Kaseti z’obuzaale ez’okuvunda kwa naphthalene zizuuliddwa nga zisangibwa ku bintu eby’enjawulo ebitambula nga plasmids (conjugative ne non-conjugative), transposons, genomes, ICEs, n’okugatta ebika bya bakitiriya eby’enjawulo (Figure 5). Mu Pseudomonas G7, operons za nah ne sal eza plasmid NAH7 ziwandiikibwa mu ngeri y’emu era nga kitundu kya transposon eriko obuzibu eyeetaaga transposase Tn4653 okusobola okukungaanya (Sota et al., 2006). Mu kika kya Pseudomonas NCIB9816-4, gene yasangibwa ku conjugative plasmid pDTG1 nga operons bbiri (nga zaawukana nga 15 kb) ezaawandiikibwa mu makubo ag’enjawulo (Dennis ne Zylstra, 2004). Mu kika kya Pseudomonas putida AK5, plasmid etali ya kuyungibwa pAK5 ekola enkodi y’enziyiza evunaanyizibwa ku kuvunda kwa naphthalene ng’eyita mu kkubo lya gentisate (Izmalkova et al., 2013). Mu kika kya Pseudomonas ekya PMD-1, operon ya nah esangibwa ku chromosome, so nga operon ya sal esangibwa ku plasmid ekwatagana pMWD-1 (Zuniga et al., 1981). Naye mu Pseudomonas stutzeri AN10, obuzaale bwonna obw’okusaanyawo naphthalene (nah ne sal operons) busangibwa ku chromosome era kiteeberezebwa nti buwandiikibwa okuyita mu bikolwa eby’okukyusa, okugatta, n’okuddamu okusengeka (Bosch et al., 2000). Mu mubiri gwa Pseudomonas sp. CSV86, operons za nah ne sal zisangibwa mu genome mu ngeri ya ICE (ICECSV86). Ensengekera ekuumibwa tRNAGly nga egobererwa okuddiŋŋana obutereevu okulaga ebifo eby’okugatta/okukwatagana (attR ne attL) n’ekiyungo ekiringa phage ekisangibwa ku nkomerero zombi eza tRNAGly, bwe kityo mu nsengeka efaananako n’ekirungo kya ICEclc (ICEclcB13 mu Pseudomonas knackmusii olw’okuvunda kwa chlorocatechol). Kigambibwa nti obuzaale ku ICE busobola okukyusibwa nga buyita mu kuyungibwa n’emirundi gy’okutambuza emitono ennyo (10-8), bwe kityo ne kikyusa eby’obugagga by’okuvunda eri oyo afuna (Basu and Phale, 2008; Phale et al., 2019).
Obuzaale obusinga obuvunaanyizibwa ku kuvunda kwa carbaryl bubeera ku plasmids. Obulwadde bwa Arthrobacter sp. RC100 erimu plasmids ssatu (pRC1, pRC2 ne pRC300) nga ku zino plasmids bbiri ezikwatagana, pRC1 ne pRC2, ziwandiika enziyiza ezikyusa carbaryl okufuuka gentisate. Ku luuyi olulala, enziyiza ezikwatibwako mu kukyusa gentisate okudda mu bitundu ebikyusa kaboni eby’omu makkati zisangibwa ku chromosome (Hayaatsu et al., 1999). Bakitiriya ez’ekika kya Rhizobium. Ekika kya AC100, ekikozesebwa okukyusa carbaryl okudda mu 1-naphthol, kirimu plasmid pAC200, etambuza cehA gene ewandiika CH ng’ekitundu kya Tnceh transposon eyeetooloddwa ensengekera eziringa elementi z’okuyingiza (istA ne istB) (Hashimoto et al., 2002). Mu kika kya Sphingomonas CF06, ensengekera y’okusaanyawo carbaryl kirowoozebwa nti eri mu plasmids ttaano: pCF01, pCF02, pCF03, pCF04, ne pCF05. DNA homology ya plasmids zino eri waggulu, ekiraga nti waliwo ekintu ekibaawo mu kuddiŋŋana kw’obuzaale (Feng et al., 1997). Mu kiwuka ekiyitibwa symbiont ekivunda carbaryl ekirimu ebika bya Pseudomonas bibiri, ekika 50581 kirimu plasmid ekwatagana pCD1 (50 kb) ewandiika enkodi ya mcd carbaryl hydrolase gene, so nga plasmid ekwatagana mu kika 50552 ewandiika enziyiza evunda 1-naphthol (Chapalamadugu ne Chaudhry, 1991) Enkola y’okusomesa abantu. Mu kika kya Achromobacter WM111, ensengekera ya mcd furadan hydrolase esangibwa ku plasmid ya 100 kb (pPDL11). Ensengekera eno eragiddwa okuba ku plasmid ez’enjawulo (100, 105, 115 oba 124 kb) mu bakitiriya ez’enjawulo okuva mu bitundu eby’enjawulo (Parekh et al., 1995). Mu mubiri gwa Pseudomonas sp. C5pp, obuzaale bwonna obuvunaanyizibwa ku kuvunda kwa carbaryl busangibwa mu genome ebuna 76.3 kb of sequence (Trivedi et al., 2016). Okwekenenya ensengekera y’obutonde (6.15 Mb) kwalaga nti waliwo MGE 42 ne GEI 36, nga ku zino MGE 17 zaali mu supercontig A (76.3 kb) nga zirina G+C ezitali za kigero (54–60 mol%), ekiraga nti ebiyinza okubaawo mu kukyusa ensengekera y’obutonde (horizontal gene transfer events) (Trivedi et al., 2016). P. putida XWY-1 eraga enteekateeka y’emu ey’obuzaale obuvunda carbaryl, naye obuzaale buno busangibwa ku plasmid (Zhu et al., 2019).
Ng’oggyeeko obulungi bw’okukyusakyusa mu mubiri ku mitendera gy’ebiramu n’ensengekera y’obutonde, obuwuka obutonotono era bulaga eby’obugagga ebirala oba eby’okuddamu nga chemotaxis, eby’obugagga by’okukyusa ku ngulu w’obutoffaali, okugabanya mu bitundu, okukozesa obulungi, okukola ebirungo ebikola ebiramu, n’ebirala, ebibiyamba okukyusa obulungi obucaafu obuwunya mu mbeera ezirimu obucaafu (Ekifaananyi 7).
Ekifaananyi 7. Enkola ez’enjawulo ez’okuddamu kw’obutoffaali bwa bakitiriya ezisaanyaawo kaboni akawoowo akalungi okusobola okusaanyaawo obulungi ebirungo ebicaafu eby’ebweru.
Okuddamu kw’eddagala (chemotactic responses) kutwalibwa ng’ensonga ezitumbula okuvunda kw’obucaafu bw’ebiramu mu nsengekera z’obutonde ezicaafu mu ngeri ey’enjawulo. (2002) baalaga nti enkola ya chemotaxis ya Pseudomonas sp. G7 okutuuka ku naphthalene yayongera ku sipiidi y’okuvunda kwa naphthalene mu nkola z’amazzi. Ekika ky’ekika ky’omu nsiko ekya G7 kyasaanyaawo naphthalene mangu nnyo okusinga ekika kya mutant ekibulamu chemotaxis. Puloteeni ya NahY (amino acids 538 ezirina topology y’olususu) yazuulibwa nga ewandiikibwa wamu n’obuzaale bw’ekkubo ly’okusalasala (metacleavage pathway genes) ku plasmid ya NAH7, era okufaananako n’ebikyusa chemotaxis, puloteyina eno erabika ng’ekola nga chemoreceptor ey’okuvunda kwa naphthalene (Grimm ne Harwood 1997). Okunoonyereza okulala okwakolebwa Hansel et al. (2009) baalaga nti puloteyina eno ya kemotactic, naye omutindo gwayo ogw’okuvunda guli waggulu. (2011) balaze okuddamu kw’eddagala lya Pseudomonas (P. putida) eri naphthalene ow’omukka, nga okusaasaana kw’omutendera gwa ggaasi kwavaamu okutambula okutambula kwa naphthalene okugenda mu butoffaali, ekyafuga okuddamu kw’eddagala mu butoffaali. Abanoonyereza bano baakozesa enkola eno ey’okukozesa eddagala lino okukola yinginiya w’obuwuka obutonotono obwandiyongedde ku sipiidi y’okuvunda. Okunoonyereza kulaga nti amakubo g’obusimu (chemosensory pathways) era gafuga emirimu emirala egy’obutoffaali nga okugabanya obutoffaali, okulungamya enzirukanya y’obutoffaali, n’okutondebwa kw’ebiramu, bwe kityo ne kiyamba okufuga omutindo gw’okuvunda. Naye okukozesa eky’obugagga kino (chemotaxis) okusobola okuvunda obulungi kiziyizibwa ebizibu ebiwerako. Ebizibu ebikulu bye bino: (a) ebikwatagana (paralogous receptors) eby’enjawulo bitegeera ebirungo/ligandi bye bimu; (b) okubeerawo kw’ebikwata ebirala, kwe kugamba, tropism ey’amaanyi; (c) enjawulo ennene mu nsengeka mu bitundu by’obusimu eby’amaka g’ebikwata ge gamu; ne (d) obutaba na mawulire ku puloteyina za sensa za bakitiriya enkulu (Ortega et al., 2017; Martin-Mora et al., 2018). Oluusi, okuvunda kw’ebiramu (biodegradation) kwa hydrocarbons eziwunya kuleeta ebirungo ebikyusa ebiriisa/ebirungo ebingi (intermediates), ebiyinza okuba nga bya kemotactic eri ekibinja kya bakitiriya ekimu naye nga biwunya eri ebirala, ekyongera okukaluubiriza enkola. Okuzuula enkolagana ya ligands (aromatic hydrocarbons) ne chemical receptors, twazimba hybrid sensor proteins (PcaY, McfR, ne NahY) nga tugatta sensor ne signaling domains za Pseudomonas putida ne Escherichia coli, ezigenderera receptors za aromatic acids, TCA intermediates, ne naphthalene, respectively (Luu et al.,, respectively (Luu et al., NahY). 2019).
Wansi w’okufugibwa naphthalene ne polycyclic aromatic hydrocarbons endala (PAHs), ensengekera y’oluwuzi lwa bakitiriya n’obulungi bw’obuwuka obutonotono bifuna enkyukakyuka ez’amaanyi. Okunoonyereza kulaga nti naphthalene etaataaganya enkolagana y’olujegere lwa acyl okuyita mu nkolagana z’amazzi, bwe kityo n’eyongera okuzimba n’okutambula kw’olususu (Sikkema et al., 1995). Okuziyiza ekikolwa kino eky’obulabe, bakitiriya zitereeza amazzi g’olususu nga zikyusa omugerageranyo n’obutonde bwa asidi w’amasavu wakati wa asidi z’amasavu ez’amatabi ga iso/anteiso ne zikola asidi z’amasavu ezitali za mafuta aga cis-unsaturated mu isomerizing mu trans-isomers ezikwatagana (Heipieper ne de Bont, 1994). Mu Pseudomonas stutzeri eyalimibwa ku naphthalene, omugerageranyo gwa saturated to unsaturated fatty acid gweyongera okuva ku 1.1 okutuuka ku 2.1, so nga mu Pseudomonas JS150 omugerageranyo guno gweyongera okuva ku 7.5 okutuuka ku 12.0 (Mrozik et al., 2004). Bwe yakuzibwa ku naphthalene, obutoffaali bwa Achromobacter KAs 3–5 bwalaga okukuŋŋaanyizibwa kw’obutoffaali okwetoloola naphthalene crystals n’okukendeera mu cell surface charge (okuva ku -22.5 okutuuka ku -2.5 mV) nga kuwerekerwako cytoplasmic condensation ne vacuolization, ekiraga enkyukakyuka mu nsengekera y’obutoffaali n’eby’obugagga eby’okungulu kw’obutoffaali (Mohapatra et al., 2019). Newankubadde enkyukakyuka mu butoffaali/ku ngulu zikwatagana butereevu n’okutwala obulungi obucaafu obuwunya, enkola ezikwatagana ez’okukola yinginiya w’ebiramu tezinnaba kulongoosebwa bulungi. Okukyusakyusa enkula y’obutoffaali tekitera kukozesebwa okulongoosa enkola z’ebiramu (Volke and Nikel, 2018). Okusazaamu obuzaale obukosa enjawulo y’obutoffaali kireeta enkyukakyuka mu nkula y’obutoffaali. Okusazaamu obuzaale obukosa enjawulo y’obutoffaali kireeta enkyukakyuka mu nkula y’obutoffaali. Mu Bacillus subtilis, puloteyina y’obutoffaali obuyitibwa cell septum protein SepF eragiddwa nti yeenyigira mu kukola septum era yeetaagibwa ku mitendera egiddako egy’okugabanya obutoffaali, naye si gene yeetaagibwa. Okusazaamu obuzaale obuwandiika enkodi za peptide glycan hydrolases mu Bacillus subtilis kyavaamu okuwanvuwa kw’obutoffaali, okwongera ku mutindo gw’okukula ogw’enjawulo, n’okulongoosa obusobozi bw’okukola enziyiza (Cui et al., 2018).
Okugabanyaamu ekkubo ly’okuvunda kwa carbaryl kiteeseddwa okutuuka ku kuvunda okulungi okw’ebika bya Pseudomonas C5pp ne C7 (Kamini et al., 2018). Kiteesebwa nti carbaryl etambuzibwa mu kifo kya periplasmic okuyita mu septum y’olususu olw’ebweru ne/oba okuyita mu porins ezisaasaana. CH ye enzyme ya periplasmic ekola ku hydrolysis ya carbaryl okutuuka ku 1-naphthol, esinga okubeera ennywevu, esinga okutabula amazzi ate nga ya butwa. CH esangibwa mu periplasm era erina enkolagana entono ne carbaryl, bwe kityo n’efuga okutondebwa kwa 1-naphthol, bwe kityo n’eziyiza okukuŋŋaanyizibwa kwayo mu butoffaali n’okukendeeza ku butwa bwayo eri obutoffaali (Kamini et al., 2018). 1-naphthol evuddemu etambuzibwa mu cytoplasm okubuna oluwuzi olw’omunda nga egabanyiziddwamu ne/oba okusaasaana, n’oluvannyuma n’efuulibwa hydroxylated okutuuka ku 1,2-dihydroxynaphthalene n’enziyiza ey’enkolagana ey’amaanyi 1NH okwongera okukyusakyusa mu kkubo lya kaboni erya wakati.
Newankubadde nga obuwuka obutonotono bulina obusobozi bw’obuzaale n’enkyukakyuka mu mubiri okusaanyawo ensibuko za kaboni ez’obutonde (xenobiotic carbon sources), ensengeka y’ensengeka y’enkozesa yazo (kwe kugamba, okukozesa ennyo ensibuko za kaboni ennyangu okusinga enzibu) kiziyiza kinene mu kuvunda kw’ebiramu. Okubeerawo n’okukozesa ensibuko za kaboni ennyangu kikendeeza ku buzaale obuwandiika enziyiza ezisaanya ensibuko za kaboni enzibu/ezitayagala nga PAHs. Ekyokulabirako ekisomeseddwa obulungi kiri nti glucose ne lactose bwe biweebwa Escherichia coli, glucose ekozesebwa bulungi okusinga lactose (Jacob ne Monod, 1965). Pseudomonas kigambibwa nti evunda PAHs ez’enjawulo n’ebirungo bya xenobiotic nga ensibuko za kaboni. Ensengeka y’okukozesa ensibuko ya kaboni mu Pseudomonas ye asidi ez’obutonde > glucose > ebirungo ebiwunya (Hylemon ne Phibbs, 1972; Collier et al., 1996). Kyokka, waliwo ekintu ekitali ekyo. Ekyewuunyisa, Pseudomonas sp. CSV86 eraga ensengekera ey’enjawulo ey’ensengeka y’ebifo esinga okukozesa ebiwunya ebiwunya (benzoic acid, naphthalene, n’ebirala) okusinga glucose era n’ekyusakyusa hydrocarbons eziwunya obulungi ne asidi ez’obutonde (Basu et al., 2006). Mu bakitiriya eno, obuzaale bw’okuvunda n’okutambuza haidrokaboni eziwunya tebukendeezebwa ne bwe wabaawo ensibuko ya kaboni eyookubiri nga glucose oba asidi ez’obutonde. Bwe yakuzibwa mu glucose ne aromatic hydrocarbons medium, kyazuulibwa nti obuzaale bw’okutambuza glucose n’okukyusakyusa mu mubiri bwakendeezebwa, aromatic hydrocarbons zakozesebwa mu log phase esooka, ate glucose yakozesebwa mu log phase eyokubiri (Basu et al., 2006; Choudhary et al., 2017). Ku luuyi olulala, okubeerawo kwa asidi z’ebiramu tekwakosa kwolesebwa kwa nkyukakyuka ya kaboni ow’akawoowo, kale obuwuka buno busuubirwa okuba ekika ekyesimbyewo okunoonyereza ku kuvunda kw’ebiramu (Phale et al., 2020).
Kimanyiddwa bulungi nti enkyukakyuka y’ebiramu eya hydrocarbon esobola okuleeta okunyigirizibwa okw’okwokya (oxidative stress) n’okulinnyisa enziyiza z’obuwuka obuziyiza obuwuka obuleeta obulwadde mu buwuka obutonotono. Okuvunda kw’ebiramu kwa naphthalene okutakola bulungi mu butoffaali bwa phase ezitambula ne mu kubeerawo kw’ebirungo eby’obutwa kivaako okutondebwawo kw’ebika bya oxygen ebikola (ROS) (Kang et al. 2006). Okuva enziyiza ezisaanya naphthalene bwe zirimu ebibinja by’ekyuma-ekibiriiti, wansi w’okunyigirizibwa okw’okwokya, ekyuma ekiri mu puloteyina za heme ne ekyuma-ekibiriiti kijja kuba kya oxidized, ekivaako puloteyina obutakola. Ferredoxin-NADP+ reductase (Fpr), awamu ne superoxide dismutase (SOD), etabaganya enkola ya redox ekyukakyuka wakati wa NADP+/NADPH ne molekyu bbiri eza ferredoxin oba flavodoxin, bwe kityo ne kiyoola ROS n’okuzzaawo ekifo ky’ekyuma-ekibiriiti wansi w’okunyigirizibwa okw’okwokya (Li et al. 2006). Kigambibwa nti byombi Fpr ne SodA (SOD) mu Pseudomonas bisobola okuleetebwa okunyigirizibwa okw’okwokya, era okweyongera kw’emirimu gya SOD ne catalase kwalabiddwa mu bika bya Pseudomonas bina (O1, W1, As1, ne G1) mu kiseera ky’okukula wansi w’embeera eziyongerwako naphthalene (Kang et al., 2006). Okunoonyereza kulaga nti okugattako ebirungo ebiziyiza obuwuka obuleeta obulwadde nga ascorbic acid oba ferrous iron (Fe2+) kiyinza okwongera ku mutindo gw’okukula kwa naphthalene. Rhodococcus erythropolis bwe yakula mu naphthalene medium, okuwandiika kw’obuzaale bwa cytochrome P450 obukwatagana n’okunyigirizibwa kw’okwokya omuli sodA (Fe/Mn superoxide dismutase), sodC (Cu/Zn superoxide dismutase), ne recA kweyongera (Sazykin et al., 2019). Okugeraageranya omuwendo proteomic okwekenneenya obutoffaali Pseudomonas okukuzibwa mu naphthalene kwalaga nti upregulation ya puloteyina ez’enjawulo ezikwatagana n’okuddamu situleesi oxidative is a stress coping strategy (Herbst et al., 2013).
Obuwuuka obutonotono butegeezeddwa nti bukola ebirungo ebikola ku ttaka wansi w’ekikolwa ky’ensibuko za kaboni ezitawunya mazzi. Ebirungo bino ebikola ku ttaka biba bikozesebwa ebikola ku ngulu ebiyitibwa amphiphilic surface active compounds ebisobola okukola aggregates ku nsengekera z’amafuta-amazzi oba empewo-amazzi. Kino kitumbula pseudo-solubilization era kyanguyiza okusikiriza kwa hydrocarbons eziwunya, ekivaamu okuvunda obulungi kw’ebiramu (Rahman et al., 2002). Olw’ebintu bino, ebirungo ebikola ku ttaka (biosurfactants) bikozesebwa nnyo mu makolero ag’enjawulo. Okwongera eddagala erikola ku ttaka oba ebirungo ebikola ku ttaka mu butonde bwa bakitiriya kiyinza okutumbula obulungi n’omutindo gw’okuvunda kwa haidrokaboni. Mu bikozesebwa ebikola ku ttaka, rhamnolipids ezikolebwa Pseudomonas aeruginosa zisomeseddwa nnyo era nga zimanyiddwa (Hisatsuka et al., 1971; Rahman et al., 2002). Okugatta ku ekyo, ebika ebirala eby’ebirungo ebikola ku ttaka mulimu lipopeptides (mucins okuva mu Pseudomonas fluorescens), emulsifier 378 (okuva mu Pseudomonas fluorescens) (Rosenberg ne Ron, 1999), trehalose disaccharide lipids okuva mu Rhodococcus (Ramdahl, 1985), lichenin okuva mu Bacillus (Saraswathy ne Hallberg, 2002), n’ekirungo ekikola ku ttaka okuva mu Bacillus subtilis (Siegmund ne Wagner, 1991) ne Bacillus amyloliquefaciens (Zhi et al., 2017). Ebirungo bino eby’amaanyi ebikola ku ttaka biragiddwa okukendeeza ku kusika kw’okungulu okuva ku 72 dynes/cm okutuuka wansi wa 30 dynes/cm, ekisobozesa okunyiga obulungi hydrocarbon. Kigambibwa nti Pseudomonas, Bacillus, Rhodococcus, Burkholderia n’ebika bya bakitiriya ebirala bisobola okukola ebirungo eby’enjawulo ebikola rhamnolipid ne glycolipid-based biosurfactants nga bikuliddwa mu naphthalene ne methylnaphthalene media (Kanga et al., 1997; Puntus et al., 2005). Pseudomonas maltophilia CSV89 esobola okukola ekirungo ekikola obutonde eky’ebweru w’obutoffaali Biosur-Pm bwe kikuliddwa ku bikozesebwa ebiwunya nga naphthoic acid (Phale et al., 1995). Entambula y’okutondebwa kwa Biosur-Pm yalaga nti okusengejja kwayo nkola eyeesigama ku kukula ne pH. Kyazuulibwa nti obungi bwa Biosur-Pm obukolebwa obutoffaali ku pH etaliimu buzibu bwali bungi okusinga obwo ku pH 8.5. Obutoffaali obukuliddwa ku pH 8.5 bwali businga kukwata mazzi era nga bulina enkolagana ey’amaanyi eri ebirungo ebiwunya n’ebirungo ebiyitibwa aliphatic okusinga obutoffaali obukuliddwa ku pH 7.0. Mu bimera ebiyitibwa Rhodococcus spp. N6, omugerageranyo gwa kaboni ne nayitrojeni (C:N) ogw’oku ntikko n’okukoma kw’ekyuma mbeera nnungi nnyo mu kukola ebirungo ebikola obutonde eby’ebweru w’obutoffaali (Mutalik et al., 2008). Okugezaako kukoleddwa okulongoosa ensengekera y’ebiramu (biosynthesis) y’ebirungo ebikola ku ttaka (surfactins) nga tulongoosa ebika n’okuzimbulukusa. Wabula, titer y’ekirungo ekikola ku ttaka mu kifo eky’okukulizaamu kiri wansi (1.0 g/L), ekireeta okusoomoozebwa eri okufulumya mu bungi (Jiao et al., 2017; Wu et al., 2019). N’olwekyo, enkola za yinginiya w’obuzaale zikozesebwa okulongoosa enkola yaayo ey’okusengejja ebiramu. Naye, okukyusa yinginiya yaayo nzibu olw’obunene bwa operon (∼25 kb) n’okulungamya ebiramu ebizibu eby’enkola y’okutegeera kw’ekibiina (Jiao et al., 2017; Wu et al., 2019). Enkyukakyuka eziwerako mu by’obuzaale zikoleddwa mu bakitiriya ba Bacillus, okusinga nga zigendereddwamu okwongera ku kukola surfactin nga zikyusa promoter (srfA operon), okusukkiridde okulaga puloteyina y’okufulumya surfactin YerP n’ensonga ezifuga ComX ne PhrC (Jiao et al., 2017). Kyokka enkola zino ez’obuzaale zituuse ku nkyukakyuka emu oba entono mu buzaale era tezinnaba kutuuka ku kukola kwa bya busuubuzi. N’olwekyo, okwongera okunoonyereza ku nkola z’okulongoosa ezesigamiziddwa ku kumanya kyetaagisa.
Okunoonyereza ku kuvunda kw’ebiramu ebya PAH okusinga kukolebwa mu mbeera za laboratory eza bulijjo. Naye mu bifo ebirimu obucaafu oba mu mbeera ezirimu obucaafu, ensonga nnyingi ezitali za biramu n’ebiramu (ebbugumu, pH, okisigyeni, ebiriisa ebiriwo, okubeerawo kw’ebiramu mu substrate, xenobiotics endala, okuziyiza ebiva mu nkomerero, n’ebirala) biragiddwa okukyusa n’okukwata ku busobozi bw’okuvunda kw’obuwuka obutonotono.
Ebbugumu lirina kinene kye likola ku kuvunda kw’ebiramu ebya PAH. Nga ebbugumu lyeyongera, ekisengejjo kya okisigyeni asaanuuse kikendeera, ekikosa enkyukakyuka y’obuwuka obutonotono obukola omukka, okuva bwe kyetaagisa okisigyeni ya molekyu ng’ekimu ku bikozesebwa mu oxygenases ezikola enkola za hydroxylation oba ring cleavage. Kitera okumanyibwa nti ebbugumu eringi likyusa PAHs ezizadde okufuuka ebirungo eby’obutwa ennyo, bwe kityo ne kiziyiza okuvunda kw’ebiramu (Muller et al., 1998).
Kizuuliddwa nti ebifo bingi ebirimu PAH birina emiwendo gya pH egy’ekitalo, gamba ng’ebifo ebirimu obucaafu obuva mu kirombe kya asidi (pH 1–4) n’ebifo ebifuuse ggaasi ow’obutonde/amanda agafuuse ggaasi ebicaafu ne alkaline leachate (pH 8–12). Embeera zino ziyinza okukosa ennyo enkola y’okuvunda kw’ebiramu. N’olwekyo, nga tonnaba kukozesa obuwuka obutonotono mu kulongoosa obulamu, kirungi okutereeza pH nga ossaamu eddagala erisaanira (eririna obusobozi obw’ekigero oba obutono ennyo obw’okukendeeza ku oxidation) nga ammonium sulfate oba ammonium nitrate ku ttaka erya alkaline oba okusiiga liming ne calcium carbonate oba magnesium carbonate ku bifo ebirimu asidi (Bowlen et al. 1995; Gupta and Sar 2020).
Okugabibwa kwa oxygen mu kitundu ekikoseddwa y’ensonga ekoma ku mutindo gw’okuvunda kw’ebiramu ebya PAH. Olw’embeera za redox ez’obutonde, enkola z’okutereeza ebiramu mu kifo zitera okwetaaga okuyingiza omukka gwa oxygen okuva mu nsonda ez’ebweru (okulima, okusaasaanya empewo, n’okugattako eddagala) (Pardieck et al., 1992). Odenkranz ne banne. (1996) baalaga nti okugattako magnesium peroxide (ekirungo ekifulumya oxygen) mu aquifer erimu obucaafu kiyinza bulungi okulongoosa ebirungo bya BTEX. Okunoonyereza okulala kwanoonyereza ku kuvunda kwa phenol ne BTEX mu kifo mu kifo ekirimu amazzi amakyafu nga bafuyira sodium nitrate n’okuzimba enzizi eziggyamu okusobola okutuuka ku bioremediation ennungi (Bewley ne Webb, 2001).