Metabolic engineering of the 2-ketobutyrate biosynthetic pathway for 1-propanol production in Saccharomyces cerevisiae

• Main Authors: Yuya Nishimura, Terumi Matsui, Jun Ishii, Akihiko Kondo
• Format: Article
• Language: English
• Published: BMC 2018-03-01
• Series: Microbial Cell Factories
• Subjects: 1-Propanol; Yeast; S. cerevisiae; Fermentation; 2-Ketobutyrate
• Online Access: http://link.springer.com/article/10.1186/s12934-018-0883-1

Abstract Background To produce 1-propanol as a potential biofuel, metabolic engineering of microorganisms, such as E. coli, has been studied. However, 1-propanol production using metabolically engineered Saccharomyces cerevisiae, which has an amazing ability to produce ethanol and is thus alcohol-tolerant, has infrequently been reported. Therefore, in this study, we aimed to engineer S. cerevisiae strains capable of producing 1-propanol at high levels. Results We found that the activity of endogenous 2-keto acid decarboxylase and alcohol/aldehyde dehydrogenase is sufficient to convert 2-ketobutyrate (2 KB) to 500 mg/L 1-propanol in yeast. Production of 1-propanol could be increased by: (i) the construction of an artificial 2 KB biosynthetic pathway from pyruvate via citramalate (cimA); (ii) overexpression of threonine dehydratase (tdcB); (iii) enhancement of threonine biosynthesis from aspartate (thrA, thrB and thrC); and (iv) deletion of the GLY1 gene that regulates a competing pathway converting threonine to glycine. With high-density anaerobic fermentation of the engineered S. cerevisiae strain YG5C4231, we succeeded in producing 180 mg/L 1-propanol from glucose. Conclusion These results indicate that the engineering of a citramalate-mediated pathway as a production method for 1-propanol in S. cerevisiae is effective. Although optimization of the carbon flux in S. cerevisiae is necessary to harness this pathway, it is a promising candidate for the large-scale production of 1-propanol.