Production of ligninolytic enzymes by litter-decomposing fungi and their ability to decolorize synthetic dyes

Abstract

Litter-decomposing basidiomycete fungi (LDF) including environmental isolates from oak forest soil were compared with white-rot fungi for ligninolytic enzymes production and decolorization of synthetic dyes Poly B-411, Reactive Black 5, Reactive Orange 16 and Remazol Brilliant Blue R (RBBR). LDF differed significantly in laccase production. Mycena inclinata and Collybia dryophila produced significant amounts of the enzyme during the whole experiment, while the production in Stropharia rugosoannulata started after 3 weeks of cultivation. Soil isolates exhibited detectable though very low laccase activity. The highest activity of Mn-peroxidase was detected in the cultures of C. dryophila with the peak activities over 30 U l −1. In all other strains, Mn-peroxidase activity did not exceed 3 U l −1. The decolorization of 100 mg l −1 dyes after 28 days ranged 80–95% for RBBR, 60–95% for Poly B-411, 58–85% for Reactive Black 5 and 45–82% for Reactive Orange 16. The fastest degradation of Poly B-411 was performed by the strains with high levels of laccase and MnP while the decolorization of other dyes did not depend so strictly on enzyme activities. The highest decolorization of azo dyes was achieved with the LDF C. dryophila, S. rugosoannulata and the soil isolates. The presence of dyes significantly affected enzyme activities in fungal cultures.