Diversity of cultivated bacteria decomposers of monochlorinated biphenyls in the soils of a protected landscape

This study examined aerobic bacterial strains from the working collection of the laboratory of microbiology of technogenic ecosystems at "IEGM UB RAS," previously isolated from the soils of the specially protected natural area "Osinskaya Lesnaya Dacha". Sixteen strains demonstrated the highest destructive potential concerning biphenyl and its chlorinated derivatives. Based on the analysis of the nucleotide sequence of the 16S rRNA gene, the phylogenetic affiliation of these strains was established. It was shown that the proportion of representatives of the genus Achromobacter accounted for 56.25%, Rhodococcus 18.75%, Pseudomonas 12.5%, and Delftia and Stenotrophomonas both 6.25%. The strains of the genera Achromobacter and Rhodococcus achieved destruction of 2-chloro-, 3-chloro-, and 4-chlorinated biphenyls with efficiencies of 13-100% and 43100%, respectively. The efficiency of destruction of monochlorobiphenyls for representatives of the genus Pseudomonas was above 80%, except for a 69% decomposition of 4-chlorobiphenyl by the strain Pseudomonas sp. Osa 27. The strain Stenotrophomonas sp. Osa 13 most actively (71%) degraded 4-chlorobiphenyl but exhibited the lowest activity (34%) regarding 3-chlorobiphenyl. The strain Delftia sp. Osa 20 achieved complete destruction of 3-chloro- and 4-chlorobiphenyls but did not transform 2-chlorobiphenyl. Thus, aerobic bacterial cultures isolated from the soils of the protected landscape possess the ability to oxidize complex aromatic compounds that are hazardous to the environment.