Bioaugmentation potential of a vinyl chloride-assimilating Mycobacterium sp., isolated from a chloroethene-contaminated aquifer

An aerobic bacterium, Mycobacterium sp. strain TRW-2 that assimilated vinyl chloride (VC) or ethene (ETH) as the sole carbon source was isolated from a chloroethene-degrading enrichment culture. The strain TRW-2 also degraded cis-dichloroethene (cis-DCE) in mineral salts medium, but only when VC was present as the primary carbon source. However, no degradation of trans-dichloroethene or trichloroethene occurred in either the presence or absence of added VC. The measured growth yield values were 6.53 and 14.1 g protein/mol of VC and ETH utilized, respectively. Inoculation by strain TRW-2 in microcosms prepared with aquifer samples resulted in rapid degradation of VC, whereas native bacteria degraded negligible amounts of VC within the same time period, thus suggesting bioaugmentation potential of the isolate. Phylogenetic analysis of the 16S rDNA sequence of the isolate revealed 98% sequence similarity to the members of the genus Mycobacterium. In summary, the isolate's ability to degrade VC, cis-DCE, and ETH and also its ability to survive and degrade VC in the presence of other microorganisms is relevant to the remediation of VC-impacted aquifers.