Metabolic Engineering of for Xylose Utilization from Cellulosic Biomass.

Cellulosic biomass hydrolysates are rich in glucose and xylose, but most microorganisms, including , are unable to utilize xylose effectively. To address this limitation, we engineered a strain optimized for xylose metabolism through the xylose oxidoreductase pathway and promoter optimization. A promoter library with varying strengths was used to fine-tune the expression levels of the , , and genes, resulting in a strain with a strong promoter for and weaker promoters for and . This engineered strain exhibited superior growth, achieving 14 g cells/L and a maximal growth rate of 0.4 g cells/L-h in kenaf hydrolysate, outperforming a native strain by 17%. This study is the first to report the introduction of the xylose oxidoreductase pathway into , demonstrating its potential as an industrial platform for producing yeast protein and other products from cellulosic biomass.