Optimization of cellulase and xylanase production by Aspergillus niger CECT 2700 using brewery spent grain based on Taguchi design

In recent years, the interest in fungi and lignocellulosic residues as a source of enzymes production has increased, due to the high production costs that hinder the development of this technology. Recent studies have been carried out with the objective of increasing the efficiency of enzyme production by new microbial strains with potential in the synthesis of proteins and low-cost and more effective fermentation techniques. In this study, a Taguchi orthogonal matrix design and analysis of variance (ANOVA) was employed to optimize the parameters of the solid-state fermentation (SSF) process using Aspergillus niger CECT 2700 and brewery spent grain (BSG) as a substrate to improve cellulase and xylanase enzyme production. The independent variables at three levels were moisture (60, 70, and 80%), bed loading (2, 4, and 6 g), and fermentation time (3, 5, and 7 days). Cellulase and xylanase activities in units per gram of dry residue (U/gdr) were the response variables. The results indicated that bed loading was the variable that most affected enzyme production. The optimal parameters were 80% moisture, 2 g of bed loading, and 5 fermentation days, resulting in a maximum of 3.63 +/- 0.39 U/gdr of cellulase activity and 2210.23 +/- 138.50 U/gdr of xylanase activity. This study showed the potential use of Taguchi design by A. niger strain and the economic lignocellulosic residue BSG as an alternative to improve the cellulose and xylanase enzymes production.