TOLERANCE RESPONSES TOWARDS DIFFERENT CONCENTRATIONS OF POLYCHLORINATED BIPHENYLS OF LIGNINOLYTIC FUNGI NATIVE FROM MISIONES, ARGENTINA

SADAÑOSKI, MARCELA A.; ALVARENGA ADRIANA E.1; FONSECA, MARÍA I.; ZAPATA, PEDRO D.1;LEVIN, LAURA N.; VILLALBA, LAURA L.

Jornada; IX Jornadas Cientifico - Tecnologicas FCEQyN-UNaM; 2015

Polychlorinated biphenyls (PCBs) belong to the persistent organic pollutants groupbecause of their environmental recalcitrance and ecotoxicity. Although their productionwas banned a long time ago, they still persist in the environment causing a seriousenvironmental problem. Ligninolytic fungi, with their extracellular, low-substrate specificityenzymes, represent a promising alternative for the biodegradation of PCBs.The present study aims to compare the tolerance rate and the extracellular laccaseactivity 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 intransformer oil. Phanerochaete chrysosporium BKM-F 1767 and Ceriporiosis subvermisporaFP 90031, strains with recognized ligninolytic ability, were used for comparison purposes.The solid medium contained sugarcane bagasse as carbon source, supplemented withmineral salts (KH2PO4, MgSO4, CaCl2, FeSO4, CuSO4 and ZnSO4) to induce ligninolyticenzymes secretion. The mean radial growth rate was determined by measuring thediameter of the expanding colonies and it was calculated the tolerance rate of every strainin triplicate. Extracellular laccase activity was determined with 2,6-dimethoxyphenol insame solid media at the end of the experiment.Tolerance rates registered at 4 ppm of PCB with the thirty strains assayeddemonstrated that this concentration was not toxic for most of the cultures. Strains thatshowed no sensitivity towards the pollutant at this concentration were selected for furtherassays with 10 and 20 ppm of PCB. The grow rate slightly decreased with increasingpollutant concentration. Irpex lacteus BAFC 1171 and Pleurotus sajor caju registered thehighest level of tolerance. I. lacteus BAFC 1171 and P. sajor caju secreted laccase with andwithout PCB and this activity increased in plates of I. lacteus BAFC 1171 with 4 ppm ofPCB. On the basis of the results obtained up to now, the selected strains showed potentialfor their use in the bioremediation of PCBs contaminated sites and will be subject of newinvestigations.