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

Abstract

This study provides a detailed analysis of the lignocellulolytic activity of a new isolate Stereum gausapatum F28, a 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 a positive effect on enzyme production and that the optimal stillage concentration differed depending on the enzyme type (for laccase it was <5 %, manganese peroxidase ≈12 %, cellulase ≈21 % and xylanase ≈16 %), which should be taken into consideration when optimizing the desired process.