Efficient lignin degradation of corn stalk by Trametes with high laccase activity and enzymatic stability in salt and ionic liquid

Abstract

The screening of new potential microbes for the selective degradation of lignin makes agricultural straws available to achieve the complete conversion to biofuel. Because of the capability of laccase to oxidize phenolic compounds and to reduce the molecular oxygen of water, laccase has attracted much interest in recent years for its industrial applications. In this study, a fungal strain with a relatively high laccase activity was isolated from corn farm residue and identified as Trametes KS-2. The maximum laccase activity was 631 U/L for Trametes KS-2 when glucose/corn stalk (1/1, w/w) and peptone were used as the carbon source and nitrogen source, with 0.09 mmol of Cu2+ at pH 5.5 and 28 °C for 10 days. Laccase activity of Trametes KS-2 was relatively stable in the presence of salt and an ionic liquid. Scanning electron microscopy analysis indicated the morphological alteration of lignocelluloses via Trametes KS-2 treatment. Remarkable degradation of lignin in corn stalk was achieved with Trametes KS-2. After 15 days, the lignin was noticeably reduced to 76 mg, and the degradation rate was increased to 65.4%. Trametes KS-2 could be potentially utilized in the microbial degradation of lignin for lignocellulosic biomass and the industrial production of laccase.