A new approach for Chrysoporthe cubensis cellulolytic cocktail production using solid and submerged-state fermentation

The lignocellulosic material bioconversion to bioproducts has received significant attention in recent years. Cellulases and hemicellulases catalyze the hydrolysis of lignocellulosic materials into fermentable sugars that are afterward converted to bioproducts by microorganisms. Chrysoporthe cubensis grown under solid-state fermentation (SSF) has produced more effective enzymatic extracts for sugarcane bagasse saccharification than commercial cellulolytic preparations. However, the investigation of new approaches for enzyme production by this fungus is still lacking. In this work, an enzyme cocktail (SSF-SmF-cocktail) was produced by extracting enzymes of C. cubensis grown under SSF using the extract produced by the same fungus under submerged fermentation (SmF). The total cellulase (FPase), carboxymethylcellulase (CMCase), cellobiohydrolase (CBH), β-glucosidase, xylanase, β-xylosidase, β-galactosidase, α-galactosidase, and α-arabinofuranosidase activities were evaluated in crude extracts obtained from C. cubensis cultivation under SSF, SmF, and also in the SSF-SmF-cocktail. The C. cubensis protein profiles cultivated under SSF and SmF were compared by SDS-PAGE. Extract produced by C. cubensis grown under SmF presented proteins with estimated molecular weights of 10.7, 29.3, 38.6, 46.0, and 170.0 kDa, respectively, but not in that produced by this fungus under SSF. When cultivated under SSF, C. cubensis produced an extract with greater protein diversity between 13 and 51 kDa than that obtained by this fungus under SmF. The 83.0 and 95.3 kDa protein bands were present in both C. cubensis cultures. The C. cubensis SSF-SmF-cocktail presented better efficiency in glucose release after 48 h of the alkali-pretreated sugarcane bagasse hydrolysis when compared to those produced by this fungus under either SSF or SmF. This extract showed the highest xylananase/FPase rate and the second highest CMCase/FPase and b-glucosidase/FPase rates among the evaluated extracts, suggesting that these enzymes are the main determinants of this cocktail the efficiency on the alkali pretreated sugarcane bagasse sacchariffication process. These results demonstrated that the enzymes produced by C. cubensis cultivated under SSF and SmF are complementary for the alkali-pretreated sugarcane bagasse enzymatic hydrolysis, since the SSF-SmF-cocktail was more efficient than other extracts produced by this fungus and that the commercial Accellerase ® . Therefore, the SSF-SmF-cocktail is a promising alternative for industrial applications. Graphical abstract