Potential of aSaccharomyces cerevisiaerecombinant strain lacking ethanol and glycerol biosynthesis pathways in efficient anaerobic bioproduction

Abstract

Saccharomyces cerevisiae shows high growth activity under low pH conditions and can be used for producing acidic chemicals such as organic acids as well as fuel ethanol. However, ethanol can also be a problematic by-product in the production of chemicals except for ethanol. We have reported that a stable low-ethanol production phenotype was achieved by disrupting 6 NADHdependent alcohol dehydrogenase genes of S. cerevisiae. Moreover, the genes encoding the NADH-dependent glycerol biosynthesis enzymes were further disrupted because the ADH-disrupted recombinant strain showed high glycerol production to maintain intracellular redox balance. The recombinant strain incapable producing ethanol and glycerol could have the potential to be a host for producing metabolite(s) whose biosynthesis is coupled with NADH oxidation. Indeed, we successfully achieved almost 100% yield for L-lactate production using this recombinant strain as a host. In addition, the potential of our constructed recombinant strain for efficient bioproduction, particularly under anaerobic conditions, is also discussed.

The quest for lower alcoholic wines

“…In fact, most of the S. cerevisiae strains possess several ADH genes codifying for alcohol dehydrogenases (although the number might vary depending on the strain background), and it has been shown that mutating a single gene have no effect in ethanol production whatsoever. Due to compensatory mechanisms, no significant ethanol reduction is detected unless a combination of several ADH genes is knocked down at the same time (Ida et al ., ; Hirasawa et al ., ). This indicates that in order to achieve a desired amount of ethanol production, those compensatory genetic mechanisms have to be very well analysed and predicted.…”

“…Gpd1p/Gpd2p use glyceraldehyde-3-phosphate derived from glycolysis, and its production is regulated according to cell demands. (Ida et al, 2012;Hirasawa et al, 2014). This indicates that in order to achieve a desired amount of ethanol production, those compensatory genetic mechanisms have to be very well analysed and predicted.…”