In spite of its high chemical stability, is known to be biodegradable, with its different electron acceptors under anaerobic conditions. However, our understanding of the initial activation reaction and the responsible prokaryotes is limited. In this study, bacterial culture that oxidizes benzene-enriched carbon dioxide under sulfate reducing conditions was used. Community analysis using terminal restriction fragment length polymorphism, 16S rRNA gene sequence and FISH revealed 95% dominance of one phylotype affiliated with the Gram-positive bacterium genus Desulfotomaculum reducens show that sulphate-reducing Gram-positive bacteria involved in anaerobic degradation of benzene. In order to get indications of the original activation mechanism substrate utilization co-metabolism tests and screened for possible metabolites were used. Phenol, toluene and benzoate could not be used as alternative carbon sources by benzene-degrading culture. Co-metabolic degradation experiments resulted in slow motion speed degradation of benzene in the presence of phenol which toluene had no effect on benzene metabolism. Phenol, 2-hydroxybenzoate, 4-hydroxybenzoate, and benzoate were identified as possible metabolites in the enrichment culture. However hydroxylated aromatics demonstrated abiotic formed. Thus, the determination of benzoate as an intermediate medium directly carboxylation of benzene as the first activation mechanism, but additional reactions leading to its formation cannot be definitely ruled out.
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