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Evolutionary engineering of Saccharomyces cerevisiae for efficient conversion of red algal biosugars to bioethanol

Lee, Hye-Jin, Kim, Soo-Jung, Yoon, Jeong-Jun, Kim, Kyoung Heon, Seo, Jin-Ho, Park, Yong-Cheol
Bioresource technology 2015 v.191 pp. 445-451
Gelidium, Saccharomyces cerevisiae, algae, bioethanol, ethanol, ethanol production, fermentation, galactose, genes, hydrolysates, mutants, transcription (genetics)
The aim of this work was to apply the evolutionary engineering to construct a mutant Saccharomyces cerevisiae HJ7-14 resistant on 2-deoxy-d-glucose and with an enhanced ability of bioethanol production from galactose, a mono-sugar in red algae. In batch and repeated-batch fermentations, HJ7-14 metabolized 5-fold more galactose and produced ethanol 2.1-fold faster than the parental D452-2 strain. Transcriptional analysis of genes involved in the galactose metabolism revealed that moderate relief from the glucose-mediated repression of the transcription of the GAL genes might enable HJ7-14 to metabolize galactose rapidly. HJ7-14 produced 7.4g/L ethanol from hydrolysates of the red alga Gelidium amansii within 12h, which was 1.5-times faster than that observed with D452-2. We demonstrate conclusively that evolutionary engineering is a promising tool to manipulate the complex galactose metabolism in S. cerevisiae to produce bioethanol from red alga.