Lignocellulolytic enzyme cocktail produced by plant endophytic Chaetomium globosum exhibits a capacity for high-efficient saccharification of raw rice straw

Abstract

The aim of this work was to optimize the production of lignocellulolytic enzyme cocktail by a plant endophyte Chaetomium globosum DX-THS3 under solid-state fermentation, and to evaluate the saccharification efficiency of this enzyme cocktail on raw rice straw. The process variables, including substrate type, substrate size, initial moisture content of substrate, culture temperature and fermentative time, were optimized using One-factor at a time approach and Response surface methodology. The results showed that the maximum CMCase, FPase and xylanase production reached 237.04 U/g, 54.8 U/g, and 987.33 U/g, respectively. Meanwhile, the lignocellulolytic enzyme cocktail exhibited good thermal stability between 30 °C and 60 °C, and excellent tolerance to acidic pH values of 3–6. Subsequently, the saccharification of raw rice straw by the enzyme cocktail was performed. After 24 h hydrolysis of raw rice straw, high reducing sugars yield (294.36 mg/g) and hydrolytic rate (47.58 %) were achieved. Furthermore, scanning electron micrograph also indicated that the enzyme cocktail had high hydrolysis performance for raw rice straw. Overall, our result provides a novel class of lignocellulolytic enzyme cocktail with a capacity for high-efficient and eco-friendly saccharification of raw rice straw, and strongly suggests plant endophytic fungi as excellent candidates for the production of lignocellulolytic enzymes.