Examination and optimization of lignocellulolytic activity of Stereum gausapatum F28 on beechwood sawdust supplemented with molasses stillage

Abstract

This study provides detailed analysis of the lignocellulolytic activity of a new isolate Stereum gausapatum F28, Serbian autochthonous fungi, on beechwood sawdust supplemented with cheap waste, sugar beet molasses stillage. Advanced multiple response optimization techniques were applied to improve ligninolytic and reduce hydrolytic activity as a requirement for potential biorefinery use. The applied techniques were supposed to select cultivation conditions that would give manganese peroxidase and laccase activities above 0.84 and 0.12 U g-1 substrate, respectively, and cellulase and xylanase activities below 1.12 and 1.4 U g-1 substrate. The optimal cultivation conditions that met the set requirements included molasses stillage concentration of 10 %, substrate moisture content of 53 %, incubation temperature of 23.5?C, and pH 5.2. The research showed that the addition of molasses stillage had positive effect on the enzyme production and that the optimal stillage concentration differed depending on the enzyme type (for laccase it was <5 %, manganese peroxidase ~12 %, cellulase ~21 %, xylanase ~16 %), which should be taken into consideration when optimizing the desired process.