Effects of plant terpenes on biodegradation of polychlorinated biphenyls (PCBs)

Effects of four plant materials containing terpenes - orange peels, tangerine peels, pine needles, and ivy leaves, and two synthetic terpenes - carvone and limonene, on the biodegradation of DELOR 103, a commercial mixture of polychlorinated biphenyls (PCBs), by Pseudomonas stutzeri, a bacterial isolate from long-term PCB-contaminated soil, were studied. The highest biodegradation of PCBs studied in minimal mineral medium with the addition of mentioned plant materials was observed in the presence of ivy leaves (52.8%) and pine needles (50.5%). The enhancement of biodegradation was observed in some cases even without the increase of bacterial biomass. Addition of synthetic terpenes, limonene and carvone, resulted in an effect similar to that observed with biphenyl, known as inducer of PCB degradation. It is concluded that the role of different plant terpenes should be further studied in more detail to evaluate exactly if terpenes serve as inducers of biphenyldioxygenase, the most important enzyme in PCB-biodegradation pathway or as biostimulators of bacterial growth representing thus an additional carbon source. ► Four plant materials containing terpenes as potential biostimulators or inducers of PCB biodegradation. ► Enhancement of biodegradation was observed in the presence of ivy leaves even without the increase of bacterial biomass. ► Addition of synthetic terpenes had similar effect to that observed with biphenyl.