Fermentation performance of engineered and evolved xylose‐fermenting Saccharomyces cerevisiae strains

Abstract

Lignocellulose hydrolysate is an abundant substrate for bioethanol production. The ideal microorganism for such a fermentation process should combine rapid and efficient conversion of the available carbon sources to ethanol with high tolerance to ethanol and to inhibitory components in the hydrolysate. A particular biological problem are the pentoses, which are not naturally metabolized by the main industrial ethanol producer Saccharomyces cerevisiae. Several recombinant, mutated, and evolved xylose fermenting S. cerevisiae strains have been developed recently. We compare here the fermentation performance and robustness of eight recombinant strains and two evolved populations on glucose/xylose mixtures in defined and lignocellulose hydrolysate-containing medium. Generally, the polyploid industrial strains depleted xylose faster and were more resistant to the hydrolysate than the laboratory strains. The industrial strains accumulated, however, up to 30% more xylitol and therefore produced less ethanol than the haploid strains. The three most attractive strains were the mutated and selected, extremely rapid xylose consumer TMB3400, the evolved C5 strain with the highest achieved ethanol titer, and the engineered industrial F12 strain with by far the highest robustness to the lignocellulosic hydrolysate. B

Synthesis of Transportation Fuels from Biomass: Chemistry, Catalysts, and Engineering

“…Organisms have been developed that ferment both xylose and glucose. 265,266 The ethanol water solutions are distilled to around 95% ethanol, where ethanol and water form an azetrope. Ethanol is further purified using molecular sieves.…”

Cellulosic ethanol production from AFEX-treated corn stover using Saccharomyces cerevisiae 424A(LNH-ST)

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“…The tolerance towards inhibitors in plant biomass hydrolysates differs considerably among S. cerevisiae strains (Sonderegger et al 2004). Therefore, depending on the composition of the biomass hydrolysates and the complexity of the intended metabolic engineering strategy, it may be useful to select a host strain with an appropriate inhibitor tolerance.…”