Optimization of Culture Conditions for Production of Cellulase by Stenotrophomonas maltophilia

Stenotrophomonas maltophilia is a microorganism that exhibits a wide range of applications. In this study, a Box-Behnken design was used to determine the optimum parameters for maximizing the cellulase production by S. maltophilia isolated from soil. The factors that were evaluated were the pH (3 to 10), carbon source (0.5 wt.% to 1.5 wt.% carboxymethylcellulose), and nitrogen source (0.5 wt.% to 1.5 wt.% yeast extract). The results showed that a maximum cellulase activity of 0.082 U/mL was achieved at a pH of 6.3, a 0.72% carbon source concentration, and a 1.5% nitrogen source concentration. Stenotrophomonas maltophilia was grown on sterilized wheat straw (WS) to evaluate the production of reducing sugars as a potential application in a biorefinery scheme. After 72 h of incubation at 30 °C, the final concentration of reducing sugars was 150 mg/L ± 2 mg/L and the corresponding yield was 10.16%. The hydrolyzed WS was mapped by synchrotron micro Fourier transform infrared spectroscopy, where a significant reduction in the characteristic signals for hemicellulose and cellulose was observed.