An optimized protocol for estimating cellulase activity in biological samples

Cellulase is a microbial enzyme responsible for degrading the β-1,4 glycoside bond in polysaccharide cellulose, which is abundant in various animal foodstuffs. Cellulase is an important industrial enzyme used for various purposes, including biopolishing textile fibers, softening garments, biostoning denim fabric, and removing excess color from textiles. In the food industry, cellulase is combined with pectinase and hemicellulase. Therefore, the need for a reliable, fast, and inexpensive cellulase activity protocol that could be used with diverse biological and environmental samples is great. This study developed a novel method to quantify cellulase activity using picric acid (PCA), which reacts with generated glucose molecules to produce mahogany red picramic acid. This PCA-cellulase method uses sodium hydroxide instead of sodium carbonate to provide alkalinity in the reaction solution, increasing the stability of picramic acid and the sensitivity and linearity of the reaction. It also overcomes the limitations of previous methods. It is notable for its dependence on few chemicals with low concentrations compared to previous methods that depend on many chemicals with high concentrations. The PCA-cellulase method was optimized using the Box-Behnken design, and its accuracy was determined using a response surface approach. A Bland-Altman cellulase activity graph was used to validate the PCA-cellulase method with a correlation coefficient of 0.9991. Therefore, the novel PCA-cellulase method provides accurate results that are comparable to existing methods.