Plant terpenes enhance survivability of polychlorinated biphenyl (PCB) degrading Pseudomonas pseudoalcaligenes KF707 labeled with gfp in microcosms contaminated with PCB

Polychlorinated biphenyls are toxic pollutants and their degradation is quite slow in the environment. Recently, interest in bioremediation using PCB-degrading bacteria has increased. In a previous report, plant terpenes (p-cymene, (S)-(-)-limonene, α-pynene, and α-terpinene) have been found to be utilized by a PCB degrader and to induce the biphenyl dioxygenase gene in pure culture. In this study, Pseudomonas pseudoalcaligenes KF707, a PCB-degrading Gram-negative soil bacterium, was used to determine whether the terpene stimulation of PCB degrader occurred in the natural environment. First, P. pseudoalcaligenes KF707 was genetically tagged using a transposon with gfp (green fluorescent protein) as a reporter gene. The population dynamics of P. pseudoalcaligenes KF707 harboring gfp gene in a PCB-contaminated environment was examined with or without terpenoids added to the microcosm. About 10-100-fold increase was found in the population of PCB degraders when terpene was added, compared with control (non-terpenes samples and biphenyl added samples). It was proposed that the gfp-monitoring system is very useful and terpenes enhance the survivability of PCB degraders in PCB-contaminated environments.