Biodegradation of polycyclic aromatic hydrocarbons by a thermotolerant white rot fungus Trametes polyzona RYNF13

摘要

The biodegradation of three polycyclic aromatic hydrocarbons (PAHs), phenanthrene, fluorene, and pyrene, by a newly isolated thermotolerant white rot fungal strain RYNF13 from Thailand, was investigated. The strain RYNF13 was identified as Trametes polyzona, based on an analysis of its internal transcribed spacer sequence. The strain RYNF13 was superior to most white rot fungi. The fungus showed excellent removal of PAHs at a high concentration of 100 mg.L-1. Complete degradation of phenanthrene in a mineral salt glucose medium culture was observed within 18 days of incubation at 308 degrees C, whereas 90% of fluorene and 52% of pyrene were degraded under the same conditions. At a high temperature of 428 degrees C, the strain RYNF13 was still able to grow, and degraded approximately 68% of phenanthrene, whereas 48% of fluorene and 30% of pyrene were degraded within 32 days. Thus, the strain RYNF13 is a potential fungus for PAH bioremediation, especially in a tropical environment where the temperature can be higher than 408 degrees C. The strain RYNF13 secreted three different ligninolytic enzymes, manganese peroxidase, laccase, and lignin peroxidase, during PAH biodegradation at 308 degrees C. When the incubation temperature was increased from 308 degrees C to 378 degrees C and 428 degrees C, only two ligninolytic enzymes, manganese peroxidase and laccase, were detectable during the biodegradation. Manganese peroxidase was the major enzyme produced by the fungus. In the culture containing phenanthrene, manganese peroxidase showed the highest enzymatic activity at 179 U.mL(-1). T. polyzona RYNF13 was determined as a potential thermotolerant white rot fungus, and suitable for application in the treatment of PAH-containing contaminants.