Improvement of cellulase and xylanase production by solid‐state fermentation of Stachybotrys microspora

Abstract

The current study investigated the production of cellulases and xylanases from the rare fungus Stachybotrys microspora under solid-state fermentation (SSF) on wheat bran (WB). A comparison of both activities was first performed in submerged cultures using various concentrations of WB, glucose, and cellulose as substrates. The maximal activity of β-glucosidases and xylanases was obtained with 2% and 4% WB, respectively, whereas cellulose yielded the highest endoglucanase production. The SSF conditions were therefore consequently optimized. A moisture content of 70% gave the most significant levels of enzyme production. Inoculation by spores led to better results than by preculture, with 10(5) spores per gram of dried matter as the best inoculum dose for all activities tested. Interestingly, the WB-based medium need not to be supplemented by an exogeneous nitrogen source. Considering the richness of S. microspora secreted proteins as lytic hydrolases, the crude extracellular enzyme extracts were successfully tested in two different biotechnological fields: protoplasting of fungi and subsequent extraction of their DNA, paper pulp hydrolysis to produce fermentable sugars.