High activity of xylose reductase and xylitol dehydrogenase improves xylose fermentation by recombinant Saccharomyces cerevisiae

Karhumaa, Kaisa; Fromanger, Romain; Hahn‐Hägerdal, Bärbel; Gorwa-Grauslund, Marie-Françoise

doi:10.1007/s00253-006-0575-3

Cited by 173 publications

(172 citation statements)

References 34 publications

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“…Reductive metabolism of acetate occurs during the solventogenic phase by some Clostridium species, where acetate can be converted to ethanol using surplus NADH generated during the acidogenic phase 24 . By contrast to the redox-neutral xylose isomerase (XI) pathway for converting xylose into xylulose 25,26 , we reason that the surplus NADH generated from xylose metabolism using the XR/XDH pathway could provide the reducing equivalent for acetate reduction. Conversely, reduction of acetate to ethanol could serve as an electron sink to alleviate the redox cofactor imbalance resulting from xylose fermentation (Fig.…”

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confidence: 99%

“…1). Notably, XR-XDH-carrying strains have significantly higher xylose consumption rates, specific ethanol productivity and final ethanol concentration, when compared with otherwise isogenic XI-carrying strains, although XI strains achieve higher ethanol yields 26 . Therefore, here we aim to implement the acetate reduction pathway together with the XR-XDH pathway in S. cerevisiae.…”

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Enhanced biofuel production through coupled acetic acid and xylose consumption by engineered yeast

et al. 2013

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The anticipation for substituting conventional fossil fuels with cellulosic biofuels is growing in the face of increasing demand for energy and rising concerns of greenhouse gas emissions. However, commercial production of cellulosic biofuel has been hampered by inefficient fermentation of xylose and the toxicity of acetic acid, which constitute substantial portions of cellulosic biomass. Here we use a redox balancing strategy to enable efficient xylose fermentation and simultaneous in situ detoxification of cellulosic feedstocks. By combining a nicotinamide adenine dinucleotide (NADH)-consuming acetate consumption pathway and an NADH-producing xylose utilization pathway, engineered yeast converts cellulosic sugars and toxic levels of acetate together into ethanol under anaerobic conditions. The results demonstrate a breakthrough in making efficient use of carbon compounds in cellulosic biomass and present an innovative strategy for metabolic engineering whereby an undesirable redox state can be exploited to drive desirable metabolic reactions, even improving productivity and yield.

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Enhanced biofuel production through coupled acetic acid and xylose consumption by engineered yeast

et al. 2013

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“…The ability to generate and convert fermentable sugars from lignocellulosic materials to ethanol in a cost-effective fashion is the central technological challenge to fully unlock its commercial potential (3). Unfortunately, fermentation of hydrolysates derived from pretreated lignocellulosic biomass is often preceded by washing (4), nutrient supplementation (5,6), and detoxification (7,8), which are very costly processes (9,10). The fermentability of a hydrolysate is strongly dependent on the feedstock pretreatment and strain selection.…”

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confidence: 99%

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

Lau

Dale²

2009

Proc. Natl. Acad. Sci. U.S.A.

328

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Current technology using corn stover (CS) as feedstock, Ammonia Fiber Expansion (AFEX) as the pretreatment technology, and Saccharomyces cerevisiae 424A(LNH-ST) as the ethanologenic strain in Separate Hydrolysis and Fermentation was able to achieve 191.5 g EtOH/kg untreated CS, at an ethanol concentration of 40.0 g/L (5.1 vol/vol%) without washing of pretreated biomass, detoxification, or nutrient supplementation. Enzymatic hydrolysis at high solids loading was identified as the primary bottleneck affecting overall ethanol yield and titer. Degradation compounds in AFEX-pretreated biomass were shown to increase metabolic yield and specific ethanol production while decreasing the cell biomass generation. Nutrients inherently present in CS and those resulting from biomass processing are sufficient to support microbial growth during fermentation. This platform offers the potential to improve the economics of cellulosic ethanol production by reducing the costs associated with raw materials, process water, and capital equipment.AFEX ͉ fermentation ͉ Lignocellulose ͉ biofuel

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“…Thus, many studies attempted to optimize the expression levels of the genes coding for the XR/XDH pathway or to engineer XR and XDH proteins with balanced cofactor preferences to reduce xylitol accumulation and increase the ethanol yield (19,28,(54)(55)(56)(57)(58)(59)(60). While previous efforts to improve xylose fermentation mostly focused on manipulation of enzymatic reactions related to xylose metabolism, this study demonstrated an innovative approach that controls the carbon flux by accumulating the intermediate product (i.e., xylitol) inside the cell to facilitate the reaction toward the target direction.…”

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confidence: 99%

“…Two types of xylose-assimilating pathways have been identified and used to engineer xylose-utilizing S. cerevisiae strains. One is the redox cofactor-dependent xylose reductase (XR)/xylitol dehydrogenase (XDH) pathway (8)(9)(10)(11)(12)(13)(14)(15), and the other is the redoxneutral xylose isomerase (XI) pathway (16)(17)(18)(19)(20)(21)(22)(23). Introduction of the XR/XDH pathway into S. cerevisiae by metabolic engineering approaches has been widely studied, but redox imbalance is a key problem, because XR can use both NADPH and NADH, while XDH uses NAD ϩ exclusively (6,24).…”

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Deletion of FPS1 , Encoding Aquaglyceroporin Fps1p, Improves Xylose Fermentation by Engineered Saccharomyces cerevisiae

Wei

Kim

et al. 2013

Appl Environ Microbiol

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Accumulation of xylitol in xylose fermentation with engineered Saccharomyces cerevisiae presents a major problem that hampers economically feasible production of biofuels from cellulosic plant biomass. In particular, substantial production of xylitol due to unbalanced redox cofactor usage by xylose reductase (XR) and xylitol dehydrogenase (XDH) leads to low yields of ethanol. While previous research focused on manipulating intracellular enzymatic reactions to improve xylose metabolism, this study demonstrated a new strategy to reduce xylitol formation and increase carbon flux toward target products by controlling the process of xylitol secretion. Using xylitol-producing S. cerevisiae strains expressing XR only, we determined the role of aquaglyceroporin Fps1p in xylitol export by characterizing extracellular and intracellular xylitol. In addition, when FPS1 was deleted in a poorly xylose-fermenting strain with unbalanced XR and XDH activities, the xylitol yield was decreased by 71% and the ethanol yield was substantially increased by nearly four times. Experiments with our optimized xylose-fermenting strain also showed that FPS1 deletion reduced xylitol production by 21% to 30% and increased ethanol yields by 3% to 10% under various fermentation conditions. Deletion of FPS1 decreased the xylose consumption rate under anaerobic conditions, but the effect was not significant in fermentation at high cell density. Deletion of FPS1 resulted in higher intracellular xylitol concentrations but did not significantly change the intracellular NAD ؉ / NADH ratio in xylose-fermenting strains. The results demonstrate that Fps1p is involved in xylitol export in S. cerevisiae and present a new gene deletion target, FPS1, and a mechanism different from those previously reported to engineer yeast for improved xylose fermentation.

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High activity of xylose reductase and xylitol dehydrogenase improves xylose fermentation by recombinant Saccharomyces cerevisiae

Cited by 173 publications

References 34 publications

Enhanced biofuel production through coupled acetic acid and xylose consumption by engineered yeast

Enhanced biofuel production through coupled acetic acid and xylose consumption by engineered yeast

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

Deletion of FPS1 , Encoding Aquaglyceroporin Fps1p, Improves Xylose Fermentation by Engineered Saccharomyces cerevisiae

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