Bioaugmentation of a polychlorobiphenyl contaminated soil with two aerobic bacterial strains

•Augmentation of the consortium of aerobic strains in PCB-contaminated soil was studied.•High degree of remediation of PCB-contaminated soil was achieved.•The augmented strains displayed high degrading activity to all PCB congeners in soil. The consortium of aerobic bacterial strains Rhodococcus ruber P25 and Microbacterium sp. B51 was bioaugmented in natural and industrial soils, contaminated by commercial mixture of polychlorinated biphenyls (PCBs) Sovol. The results showed that the bioaugmentation of bacterial strains led to PCBs degradation in soil. Sovol at the initial concentration of about 100mgkg−1 was removed by 72.2% in the bioaugmented system with natural soil within 90 days, while the system with industrial soil removed 96.4% of this compound within the same period. The biodegradation kinetics of PCBs in the bioaugmented soil systems was not dependent on the presence of indigenous microflora. It was found that the growth dynamics of the strains R. ruber P25 and Microbacterium sp. B51 correlated with the specific degradation of Sovol. The strains R. ruber P25 and Microbacterium sp. B51 displayed high degradative activity to all congeners (ortho-, meta- and para-substituent) contained in Sovol. Removal percentage for each congeners amounted to 59–100% in the bioaugmented systems. This study suggests that augmentation of PCB-contaminated soils with strain R. ruber P25 and Microbacterium sp. B51 is promising in PCB bioremediation.