Assessing the Ethanologenic Potential of Xylose-Fermenting Yeasts Scheffersomyces stipitis UCM Y-2810

Background. Enhancing the efficiency of second-generation (2G) bioethanol production from lignocellulosic biomass is crucial for advancing sustainable biofuel technologies. However, the conversion of biomass into 2G bioethanol faces substantial challenges, necessitating a comprehensive investigation of microbial agents. Objective. To evaluate the effect of glucose and xylose concentrations, as well as cultivation duration, on the efficiency of ethanologenesis using the model organism Scheffersomyces stipitis UCM Y-2810, and to determine the optimal conditions for achieving maximum ethanol yield. Methods. The effects of glucose and xylose concentrations and cultivation time on ethanologenesis efficiency were evaluated using S. stipitis UCM Y-2810 as a model organism. The experimental design included three levels of factors: xylose concentration (3, 16.5, and 30 g/l), glucose concentration (1, 5.5, and 10 g/l), and cultivation durations (1, 2, and 3 days). Statistical analysis of the experimental data was conducted using a three-factor, three-level Box–Behnken design. Results. Under submerged cultivation of the strain of S. stipitis UCM Y-2810 in model media, optimization of the ethanologenesis process resulted in a maximum ethanol yield of 7.74 g/l. The optimal conditions for this yield were identified as follows: xylose concentration of 16.5 g/l, glucose concentration of 7.75 g/l, and a cultivation time of 3 days. Conclusions. The application of the Box–Behnken design revealed that the statistically significant factors influencing ethanologenesis efficiency were xylose concentration, yeast cultivation duration, and the linear-quadratic interaction between these two factors.