Xylose is the second most abundant sugar in nature. Its efficient fermentation has been considered as a critical factor for a feasible conversion of renewable biomass resources into biofuels and other chemicals. The yeast Saccharomyces cerevisiae is of exceptional industrial importance due to its excellent capability to ferment sugars. However, although S. cerevisiae is able to ferment xylulose, it is considered unable to metabolize xylose, and thus, a lot of research has been directed to engineer this yeast with heterologous genes to allow xylose consumption and fermentation. The analysis of the natural genetic diversity of this yeast has also revealed some nonrecombinant S. cerevisiae strains that consume or even grow (modestly) on xylose. The genome of this yeast has all the genes required for xylose transport and metabolism through the xylose reductase, xylitol dehydrogenase, and xylulokinase pathway, but there seems to be problems in their kinetic properties and/or required expression. Self-cloning industrial S. cerevisiae strains overexpressing some of the endogenous genes have shown interesting results, and new strategies and approaches designed to improve these S. cerevisiae strains for ethanol production from xylose will also be presented in this review.

中文翻译：

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非重组酿酒酵母对 d-木糖的消耗：综述。

木糖是自然界中第二丰富的糖。其高效发酵被认为是将可再生生物质资源可行地转化为生物燃料和其他化学品的关键因素。酵母 Saccharomyces cerevisiae 由于其出色的糖发酵能力而具有特殊的工业重要性。然而，虽然酿酒酵母能够发酵木酮糖，但它被认为不能代谢木糖，因此，大量研究已针对用异源基因改造这种酵母以允许木糖消耗和发酵。对该酵母的天然遗传多样性的分析还揭示了一些非重组的酿酒酵母菌株，它们消耗木糖甚至（适度地）生长在木糖上。这种酵母的基因组具有通过木糖还原酶、木糖醇脱氢酶和木酮糖激酶途径进行木糖运输和代谢所需的所有基因，但它们的动力学特性和/或所需的表达似乎存在问题。过度表达一些内源基因的自克隆工业酿酒酵母菌株已经显示出有趣的结果，并且旨在改进这些酿酒酵母菌株以从木糖生产乙醇的新策略和方法也将在本综述中介绍。