Synergistic mineralization of biphenyl by Alcaligenes faecalis type II BPSI-2 and Sphingomonas paucimobilis BPSI-3

Polychlorinated biphenyls (PCBs) are important environmental pollutants and have been found to have adverse effects on a number of different organisms. Aerobic biodegradation of PCBs occurs through direct oxidation of the biphenyl nucleus. Biphenyl degraders are instrumental in the mineralization of PCBs to CO2 and water. Here two bacteria, Alcaligenes faecalis type II strain BPSI-2 and Sphingomonas paucimobilis strain BPSI-3, are described that exhibit synergistic mineralization of biphenyl (using C-14-UL-biphenyl) when grown as a co-culture. Mineralization rates (23.7 and 9.1 nmol nmol(-1) h(-1), respectively) and extent of mineralization (38.1% and 24.4%, respectively) were significantly different between the strains as well as when compared to the co-culture (35.2 nmol nmol(-1) h(-1) and 45.2%). Both strains were originally isolated from an enrichment culture, BSEN-2. The coculture of BPSI-2 and 3 showed a threefold increase in mineralization rate compared with the parent culture and a decrease in the time taken for (CO2)-C-14 evolution to occur. There was no significant difference in the extent of mineralization between the co-culture and BSEN-2. Examination of enrichment cultures at the community level may play a role in optimizing bioremediation programmes.