Secretome analysis of Talaromyces emersonii reveals distinct CAZymes profile and enhanced cellulase production through response surface methodology

This study reports comprehensive insight into the repertoire of proteins present in the secretome of a hypercellulolytic fungus Talaromyces emersonii and designing of new production medium containing combination of cellulose and gram flour for enhanced production of cellulases and hemicellulases. Probe into the secretome of the fungus through Quadrupole Time Of Flight Liquid Chromatography/Mass Spectrometry (Q-TOF LC/MS) revealed a total of 266 proteins that were represented by high abundance of Carbohydrate Active enzymes (CAZymes) comprising of 93 glycosyl hydrolase family, 13 cellulose binding module, 14 carbohydrate esterase, 8 auxiliary activity proteins. The zymography of endoglucanase (EG), cellobiohydrolase (CBHI), beta-glucosidase (beta G) and xylanase revealed expression of five EG, two CBHI, four beta-G and two xylanases as the major proteins. The optimization of culture conditions using RSM resulted in 113.74, 6.07, 31.23 and 177.02 Units/mL corresponding to 1.62, 1.34, 1.25 and 1.22 fold higher endoglucanase, cellobiohydrolase (CBHI), beta-glucosidase and xylanase activity, respectively, when compared to unoptimized control. The secretome produced by this strain was highly active against acid and alkali pre-treated rice straw showing 59.05 and 74.33 % saccharification, respectively, which was further enhanced when cocktail of T. emersonii and Achaetomium strumarium was used.