Complete mineralization of benzene by a methanogenic enrichment culture and effect of putative metabolites on the degradation |
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Authors: | Masumoto Hiroki Kurisu Futoshi Kasuga Ikuro Tourlousse Dieter M Furumai Hiroaki |
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Institution: | a Department of Urban Engineering, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan b Research Center for Water Environment Technology, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan |
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Abstract: | Microbial degradation of benzene under anaerobic conditions plays an important role in remediation of contaminated sites but the microorganisms and metabolic pathways involved remain poorly understood. In this study, we evaluated degradation of benzene by a methanogenic enrichment culture obtained from non-contaminated lotus field soil, alone and in the presence of several putative metabolic intermediates, that is, toluene, benzoate and phenol. Using stable isotope (13C) labeled substrate, benzene was shown to be degraded almost completely to equimolar concentrations of methane and carbon dioxide, without detectable accumulation of extracellular metabolites. Concurrently, toluene, benzoate and phenol were also effectively mineralized, but probably by microorganisms other than the benzene degraders. The latter included Hasda-A, which is putative benzene-degrading deltaproteobacterium present in the culture. While toluene and benzoate did not affect benzene degradation, phenol had a moderate inhibitory effect although it was not a major metabolic intermediate of benzene in our culture. Finally, 4-hydroxycoumarin was detected as a compound formed from phenol but further experiments are required to elucidate its relationship to degradation of phenol. |
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Keywords: | Benzene Methanogenic enrichment Biodegradation Putative metabolites |
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