Improved xylanase production using apple pomace waste by Aspergillus niger in koji fermentation

Xylanase production by Aspergillus niger NRRL‐567 in solid‐state fermentation (koji fermentation) was optimized using 2⁴ factorial design and response surface methodology. The evaluated variables were the initial moisture level and concentration of inducers veratryl alcohol (VA), copper sulphate (CS), and lactose (LAC)], leading to the response of xylanase production. Initial moisture level and LAC were found to be the most significant variable for xylanase production (p<0.05). The highest xylanase production was observed with 3578.8 ± 65.3 IU/gds (gram dry substrate) under optimal conditions using initial moisture of 85% (v/w), pH 5.0 and inducers VA (2 mM/kg), LAC 2% (w/w), and CS (1.5 mM/kg) after 48 h of incubation time. Higher xylanase activity of 3952 ± 78.3 IU/gds was attained during scale‐up of the process in solid‐state tray fermentation under optimum conditions after 72 h of incubation time. The present study demonstrates that A. niger NRRL‐567 can efficiently be used to achieve xylanase production with an economical and environmental benefit in solid‐state tray fermentation. The developed process can be used to develop an effective process for commercially feasible bioproduction of xylanases for speciality applications, such as conversion of lignocellulosic biomass to biofuels and other value‐added products.