SCREENING FUNGI FOR THEIR POSSIBLE ABILITY TO DEGRADE DIOXINS AND FURANS

摘要

Nineteen strains of white rot fungi were screened for their possible ability to degrade dioxins in solid medium containing MWI fly ashes with polyclorinated dibenzo-p-dioxins and polyclorinated dibenzofurans -^sPCDD/Fs. Growth and the presence of ligninlolytic enzymes in a liquid medium containing fly ashes was used for the selections of any promising strain. The strains that presented best growth in solid medium after 7 days were selected for liquid medium cultivation. Cerioporiopsis subvermispora SS-3, Pleurotus sp, Pleurotus sp 016, Pleurotus sp CCB 016, Pleurotus sp CCB 394, Pleurotus sp CCB 396, Pleurotus sp CCB 507, Pleurotus sp CCB 517, Pleurotus sp Florida, Pleurotus sp P1, and strain FSP 2000 did not show any ability to grow in the solid medium. Lentinus edodes presented morphologic alterations and growth was inhibited. Agaricus campestris IZ 1877, Phanerochaete chrysosporium ATCC 24725, Pleurotus sp PSC 94/03, Pleurotus tailandia, Pleurotus sajor –caju, Pleurotus sp CCB068 e Pleurotus sajor - caju 020 presented very good growth in solid medium containing 2.5 g fly ash / plate and were selected. They were cultivated for 3, 7, 10, 14, 21, 28, 35, 42, 49 and 56 days in the fly ash–containing liquid medium. All strains produced ligninperoxidase on the 3 rd day of cultivation, but the best activities were produced on the 42nd day of cultivation in the supernatants of P. PSC 94/03 and P. sajor caju 020. Laccase was detected in the supernatants of Pleurotus CCB 068 in all days tested and the greatest activity was produced on the 42nd day cultivation (20 U/L). All the other strains produced lower laccase activities. The highest manganese-peroxidase (MnP) activities were produced after 3 days for P. CCB 068 (18 U/L) and 49 days for P. crhysosporium (18 U/L). Laccase and MnP were the predominant present in the cultures media and may be involved in the degradation of PCDD/Fs. Toxicological and carcinogenic assays will be conducted for more information about the potential degradation capability of these 7 strains and their possible application in bioremediation processes.