Dual utilization of NADPH and NADH cofactors enhances xylitol production in engineered Saccharomyces cerevisiae

• Published in: Biotechnology journal 2015-12, Vol.10 (12), p.1935-1943
• Main Authors: Jo, Jung-Hyun, Oh, Sun-Young, Lee, Hyeun-Soo, Park, Yong-Cheol, Seo, Jin-Ho
• Format: Article
• Language: English
• Subjects: Aldehyde Reductase - genetics; Aldehyde Reductase - metabolism; Batch Cell Culture Techniques; Cofactor regeneration; Fermentation; Glucose-limited fed-batch fermentation; Metabolic Engineering; NAD - metabolism; NADH-preferring xylose reductase; NADP - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Xylitol; Xylitol - biosynthesis
• ISSN: 1860-6768; 1860-7314
• DOI: 10.1002/biot.201500068

Xylitol, a natural sweetener, can be produced by hydrogenation of xylose in hemicelluloses. In microbial processes, utilization of only NADPH cofactor limited commercialization of xylitol biosynthesis. To overcome this drawback, Saccharomyces cerevisiae D452‐2 was engineered to express two types of xylose reductase (XR) with either NADPH‐dependence or NADH‐preference. Engineered S. cerevisiae DWM expressing both the XRs exhibited higher xylitol productivity than the yeast strain expressing NADPH‐dependent XR only (DWW) in both batch and glucose‐limited fed‐batch cultures. Furthermore, the coexpression of S. cerevisiae ZWF1 and ACS1 genes in the DWM strain increased intracellular concentrations of NADPH and NADH and improved maximum xylitol productivity by 17%, relative to that for the DWM strain. Finally, the optimized fed‐batch fermentation of S. cerevisiae DWM‐ZWF1‐ACS1 resulted in 196.2 g/L xylitol concentration, 4.27 g/L h productivity and almost the theoretical yield. Expression of the two types of XR utilizing both NADPH and NADH is a promising strategy to meet the industrial demands for microbial xylitol production. Xylose reductase (XR) catalyzes hydrogenation of xylose to xylitol by using NADPH as cofactor. The engineered Saccharomyces cerevisiae coexpressing NADPH dependent wild XR and NADH preferring mutant XR produces xylitol efficiently. Additional expression of cofactor regeneration enzymes (ZWF1 and ACS1) improves xylitol productivity further. Dual utilization of NADPH and NADH is a promising strategy for microbial production of xylitol on an industrial scale. This article is part of an AFOB (Asian Federation of Biotechnology) Special issue. To learn more about the AFOB, visit www.afob.org.