Polysaccharide-hydrolysing secretome of Schizophyllum commune during growth on different carbon sources

Abstract

In the present work, the polysaccharide-hydrolysing secretome of Schizophyllum commune BCC 632 was analysed in submerged fermentation conditions to elucidate the effect of chemically and structurally different carbon sources on the expression of cellulases and xylanase. Among polymeric substrates, crystalline cellulose appeared to be the best carbon source providing the highest endo- glucanase (53.5 U/mL), total cellulase (9.2 U/mL), and xylanase (636.1 U/mL) activities. The use of mandarin pomace as a growth substrate also allowed to achieve high volumetric activities of all target enzymes whereas wheat straw and xylan turned out to be the weakest inducers of enzyme production. The supplementation of the Avicel or wheat straw-based medium with a low concentration of easily metabolizable carbon source (mandarin pomace or glycerol) favored enzyme secretion. The addition of 0.5% glucose to the Avicel-containing medium caused short-term catabolite repression of the synthesis of both cellulase and xylanase while the addition of α-deoxy-D-glucose prevented enzyme secretion. It was shown that the presence of compounds inducing the formation of cellulase and xylanase by S. commune BCC 632 depends on the age of the fungal culture.