Tolerance responses towards different concentrations of PCBs of ligninolytic fungi native from Misiones, Argentina

M. SADAÑOSKI; A.E. ALVARENGA; M.I. FONSECA; P.D. ZAPATA; L.N. LEVIN; L.L. VILLALBA

Buenos Aires

Congreso; SETAC Latin America 11th Biennial Meeting; 2015

The Society of Environmental Toxicology and Chemistry

Polychlorinated biphenyls (PCBs) belong to the persistent organic pollutantsgroup because of their environmental recalcitrance and ecotoxicity. Althoughtheir production was banned a long time ago, they still persist in the environment causing a serious environmental problem. Ligninolytic fungi, with their extracellular, low-substrate specificity enzymes, represent a promisingalternative for the biodegradation of PCBs. The present study aims to comparethe growth rates and the extracellular laccase activity at different concentrations of PCBs of white rot fungi native from Misiones Province (Argentina) with potential use in the bioremediation of contaminated sites. The fungal strains were tested for their growth rate in solid media containing PCB in transformer oil. Phanerochaete chrysosporium BKM-F 1767 and Ceriporiosis subvermispora FP 90031, strains with recognized ligninolytic ability, were used for comparison purposes. The solid medium contained sugarcane bagasse as carbon source,supplemented with mineral salts (KH2PO4, MgSO4, CaCl2, FeSO4, CuSO4 andZnSO4) to induce ligninolytic enzymes secretion. The mean radial growth ratewas determined by measuring the diameter of the expanding colonies and it wascalculated the tolerance rate of every strain in triplicate. Extracellular laccase activity was determined with 2,6-dimethoxyphenol in same solid media at the end of the experiment. Tolerance rates registered at 4 ppm of PCB with the thirty strains assayed demonstrated that this concentration was not toxic for most of the cultures. Strains that showed no sensitivity towards the pollutant at this concentration were selected for further assays with 10 and 20 ppm of PCB. The growth rate slightly decreased with increasing pollutant concentration. Irpex lacteus BAFC 1171 and Pleurotus sajor caju registered the highest level oftolerance. I. lacteus BAFC 1171 and P. sajor caju secreted laccase with andwithout PCB and this activity increased in plates of I. lacteus BAFC 1171 withPCB. On the basis of the results obtained up to now, the selected strains showedpotential for their use in the bioremediation of PCBs contaminated sites and will be subject of new investigations.