Application of ligninolytic enzyme of Lentinus polychrous on synthetic dye decolorization

Abstract

Contamination of water resources by synthetic dyes causes many environmental and health problems. Fungal ligninolytic enzymes have been applied for dye decolorization due to its ability in degrading a wide variety of recalcitrant substances. Extracellular ligninolytic enzyme production by white rot fungus, Lentinus polychrous, grown in glucose containing medium supplemented with rice straw powder and soybean pomace was monitored. Optimum condition for remazol brilliant blue R (RBBR) decolorization was studied by varying initial RBBR concentrations, pH values, and initial crude enzyme concentrations. The result revealed that the ligninolytic enzyme dominantly produced was laccase with an activity of 0.095 U/ml on day 15, and a small amount of manganese peroxidase was also detected. The crude laccase produced from L. polychrous, effectively decolorized the dye within a short period of time, that was approximately 50% of 20 mg/l RBBR was decolorized within the first 2 hours. The optimal pH for RBBR decolorization was 3.0 which had an efficiency of 87% within 6 hours after incubation. Moreover, the best redox mediator of laccase was CuSO4, whose decolorization efficiency was over twice than that of samples without this mediator. The decolorization intensified with increase of CuSO4 concentration but higher concentrations of chromium tended to suppress decolorization.