Thermostable Laccase from Psilocybe castanella: characterization and pentachlorophenol degradation
Pentachlorophenol has its use banned in several countries. In Brazil, its uncontrolled deposition resulted in soil contamination which requires strategies for decontamination. This paper aimed at describing the partial purification and characterization of a thermostable laccase produced by this fungus during its growth in soil, and assessing its role in in vitro pentachlorophenol biodegradation. For this purpose, P. castanella was cultivated in a solid system containing sandy soil. The extracellular enzyme extract was obtained by partial purification, characterized and used to evaluate the degradation of pentachlorophenol in vitro. Laccase was the only enzymatic activity detected both in the crude extract and during the following steps until preparation. The molecular mass of the partially purified laccase was estimated to be 64 KDa, with apparent KM of 0.47 μMol, and Vmax of 11.16 U. L-1. Optimum temperature and pH were 55 ° C and 2.5, respectively. The T1/2 verified at 55 ° C, 60 ° C, and 80 ° C were 19 hours, 17 hours, and 47 minutes, respectively. The highest pentachlorophenol biodegradation was 23%, at pollutant concentrations of 100 μg. L-1. Our results evidenced that thermostable laccase produced by P. castanella during its growth in soil is involved in pentachlorophenol biodegradation.