Bioprocess conditions for treating mineral transformer oils contaminated with polychlorinated biphenyls (PCBs)

Abstract

This work was aimed at developing a bioprocess for the mycoremediation of polychlorinated biphenyls (PCBs) and generating a matching early stage mass and energy balance approach to be applied in a large-scale process. Irpex lacteus BAFC 1171 and Trametes sanguinea LBM 023 capacity for PCBs biodegradation was tested under two different nutritional conditions, with 217 mg L−1 of a technical mixture of Aroclor 1242, 1254 and 1260 in oil transformer. Mass and energy balances were calculated based on a generic model developed for early stages of microbial bioprocesses estimation, employing a low-cost culture medium. Both strains not only demonstrated ability to growth, but also degraded about 68% of the PCBs mixture in an N-limited liquid medium after 35 days of incubation at 29 ± 1 °C under static conditions. PCBs addition at 217 mg L-1 modified fungal morphology, biomass, glucose consumption, proteins and laccase secretion. A 3-fold increase in protein content was observed in complex medium in PCBs presence, whereas PCBs supplementation enhanced laccase production by T. sanguinea, 5- and 40-fold in both culture media. Both strains produced approx. 34% of bioemulsifiers in absence of PCBs after 21 days of treatment, but only I. lacteus secreted them in pollutants presence (20% after 28 days). This approach provides an insight into a mycoremediation process applied to treat PCBs mineral oil.