Engineering an industrial Saccharomyces cerevisiae strain with the inulinase gene for more efficient ethanol production from Jerusalem artichoke tubers

Abstract

Engineering industrial microbial strains with inulinase production for developing a consolidated bioprocessing (CBP) strategy is a desirable solution to biofuel production from Jerusalem artichoke tubers. In this study, the integrative vector pFA6a‐rDNA‐PGK‐INU was generated by fusing the 3.3‐kb ribosomal DNA fragment with the phosphoglycerate kinase promoter to regulate the expression of the inulinase gene isolated from Kluyveromyces marxianus, which was then integrated into the chromosome of an industrial Saccharomyces cerevisiae strain for ethanol production from Jerusalem artichoke tubers. Compared to the host strain, no significant difference was observed in the growth of the recombinant yeast, but its inulinase production was enhanced: 22.9 versus 10.6 U/mL for aerobic seed cultures and 14.5 versus 10.0 U/mL for ethanol fermentation, which consequently facilitated the CBP process for ethanol production: 72.5 g/L ethanol produced in a fermentation time of 48 h, while only 67.0 g/L ethanol was produced by the host strain in a fermentation time of 60 h. Thus, the ethanol productivity was increased from 1.12 to 1.51 g/L/h, presenting an increase of 34.8%.