Efficient simultaneous utilization of glucose and xylose from corn straw by Sphingomonas sanxanigenens NX02 to produce microbial exopolysaccharide

Lignocellulosic biomass is a cheap and abundant carbon source in the microbial manufacturing industry. The native co-utilization of glucose and xylose from corn straw total hydrolysate (CSTH) by Sphingomonas sanxanigenens NX02 to produce exopolysaccharide Sanxan was investigated. Batch fermentation demonstrated that, compared to single sugar fermentation, co-substrate of glucose and xylose accelerated cell growth and Sanxan production in the initial 24 h with the same consumption rate. Additionally, NX02 converted CSTH into Sanxan with a yield of 13.10 +/- 0.35 g/Kg, which is slightly higher than that of glucose fermentation. Coexistence of three xylose metabolic pathways (Xylose isomerase, Weimberg, and Dahms pathway), incomplete phosphoenolpyruvate-dependent phosphotransferase system, and reinforced fructose metabolism were recognized as the co-utilization mechanism through comparative transcriptome analysis. Therefore, strain NX02 has a prospect of becoming an attractive platform organism to produce polysaccharides and other bio-based products derived from agricultural waste hydrolysate rich in both glucose and xylose.

Automated summary

The study found that the bacterium NX02 is able to produce exopolysaccharide from corn straw total hydrolysate with a slightly higher yield than that of glucose fermentation. Through comparative transcriptome analysis, the coexistence of three xylose metabolic pathways, incomplete phosphoenolpyruvate-dependent phosphotransferase system, and reinforced fructose metabolism were identified as the co-utilization mechanism. Therefore, strain NX02 has the potential to be an attractive platform organism for producing polysaccharides and other bio-based products from agricultural waste hydrolysate rich in both glucose and xylose.