Reappraisal of Sugarcane Bagasse for the Optimization of β-Glucosidase Production from <em>Bacillus siamensis</em> JJC33M Using a Box-Behnken Design

B. siamensis JJC33M produces a b-glucosidase (BglJ33) with transglucosylase activity on cellobiose, and hydrolytic activity on cellulose-derived substrates. B. siamensis JJC33M produces BglJ33 using various agro-industrial residues, untreated sugarcane bagasse enriched with yeast extract as one of the most efficient substrates for enzyme production. Optimization studies have not been carried out for BglJ33 production. Therefore, this study optimized BglJ33 production by B. siamensis JJC33M through the valorization of sugarcane bagasse concentration (10, 20, and 30 g/L), yeast extract concentration (2, 5, and 8 g/L), and temperature (35, 37, and 39°C) using a Box-Behnken experimental design. It was found that increasing the carbon source concentration (from 10 to 30 g/L, with 5 g/L yeast extract at 39°C) increased the volumetric activity on carboxymetilcellulose, from 0.015 to 0.055 U/mL, respectively. Intermediate concentration of yeast extract produced the highest activity, suggesting a balance between nitrogen availability and enzyme expression without causing inhibitory effects. Combination of 20 g/L sugarcane bagasse, 5 g/L yeast extract, and 37 °C resulted in the highest volumetric activity, indicating that this may be the system’s optimal condition. In conclusion, all variables had a significant effect, enhancing process efficiency, while reconsidering sugarcane bagasse to produce high-value-added molecules such as enzymes.