Statistical optimization of cellulase production by the brown rot fungi, Fomitopsis palustris, and its application in the enzymatic hydrolysis of LHW-pretreated woody biomass

Abstract

Fomitopsis palustris, screened from 11 wood rotting fungi, was optimized with a sequential optimization strategy to produce the largest amount of cellulase, and the efficiency of the enzyme was evaluated. Based on the Plackett–Burman and Box–Behnken designs, the most significant variables, time, urea, and Tween 80 were varied for optimizing cellulase production. An optimized result for FPase activity with 130.45FPU/mL was achieved for an 8-day culture containing 4.46g/L of urea and 27.83μL/L of Tween 80, which experimentally matched well with the predicted value from the model. The obtained crude cellulase was subsequently employed in the saccharification of the poplar wood, Populus tomentosa, which was pretreated with liquid hot water (LHW) at different temperatures. A maximum release of 25.15% of reducing sugars was observed after a 72-h enzymatic hydrolysis of the 180°C-LHW-pretreated poplar wood, which is 1.72 times higher than that from untreated wood (14.66%), indicating that F. palustris has a potential to produce cellulase for woody biomass hydrolysis.