Biosynthesis of 2-phenylethanol from glucose with genetically engineered Kluyveromyces marxianus

Glucosamine and its derivatives are utilized in the food and biomedical industries. However, current production relies on hydrolysis of natural sources, making it difficult to maintain quality and eliminate allergenic risk. Therefore, microbial production with aid of metabolic engineering is required. We previously demonstrated production of N-acetylglucosamine (GlcNAc) in Saccharomyces cerevisiae by overexpressing an allosteric regulation-free Gfa1p mutant and the haloacid dehalogenase-like phosphatase YqaB. In this study, we further improved GlcNAc production by reducing glycolytic flux. Eukaryotic phosphofructokinase 1 (PFK-1) is allosterically activated by fructose 2,6-bisphosphate (F26BP). Disruption of PFK-2, which synthesizes F26BP, resulted in a slight decrease of GlcNAc production and no significant change of glucose consumption and ethanol production. However, when galactose was used as a sole carbon source to the strain without PFK-2, GlcNAc production was significantly increased and ethanol production was reduced, suggesting that further reduction of glycolytic flux can be used to further improve GlcNAc production. The methodology used in this study can be applied to improve production of carbohydrate derivatives in S. cerevisiae.