Expression of Gre2p improves tolerance of engineered xylose-fermenting Saccharomyces cerevisiae to glycolaldehyde under xylose metabolism
Expression of Gre2p improves tolerance of engineered xylose-fermenting Saccharomyces cerevisiae to glycolaldehyde under xylose metabolism
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DOI：
10.1007/s00253-018-9216-x
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发表时间：
2018-09-01
影响因子：
5
通讯作者：
Jin, Yong-Su
中科院分区：
文献类型：
--
作者：
Jayakody, Lahiru N.;Turner, Timothy Lee;Jin, Yong-Su
利用木糖还原酶途径的工程酿酒酵母使木糖有效地转化为燃料和化学品。然而，热化学预处理的生物质水解液对酿酒酵母的毒性是将木糖和葡萄糖等生物质衍生糖转化为高价值产品的关键技术挑战之一。我们研究了乙醇醛（一种生物质衍生的高毒性醛类化合物）的作用，以及它与植物水解液中常见的其他主要发酵抑制剂（如甲基乙二醛、5-HMF、糠醛、香兰素和乙酸）对木糖和/或葡萄糖培养基中工程木糖发酵的酿酒酵母的联合抑制作用。结果表明，在含木糖培养基中，乙醇醛和甲基乙二醛是抑制工程木糖发酵酿酒酵母的关键短脂肪醛。事实上，这些被测试的发酵抑制剂的毒性程度随培养基的唯一碳源而变化。我们证明，将一个额外的自体GRE2拷贝与其天然启动子的基因组整合，大大提高了工程木糖发酵酿酒酵母对主要抑制化合物（包括含木糖培养基中的乙醇醛）的耐药性，以及源自芒草的富含木糖的木质纤维素水解物，同时改善了乙醇发酵谱。本研究的结果将有助于开发下一代健壮的酿酒酵母菌株，用于有效发酵生物质水解物中的己糖和戊糖。
Engineered S. cerevisiae employing the xylose reductase pathway enables efficient xylose valorization to fuels and chemicals. However, toxicity of thermochemically pretreated biomass hydrolysate on S. cerevisiae is one of the key technical challenges to upgrade biomass-derived sugars including xylose and glucose into high-value products. We investigated the effect of glycolaldehyde, one of the biomass-derived highly toxic aldehyde compounds, and its combinatorial inhibitory effect with other major fermentation inhibitors commonly found in plant hydrolysate such as methylglyoxal, 5-HMF, furfural, vanillin, and acetic acid on engineered xylose-fermenting S. cerevisiae in xylose and/or glucose media. We elucidated that glycolaldehyde and methylglyoxal are the key inhibitory short-aliphatic aldehydes on engineered xylose-fermenting S. cerevisiae in xylose-containing medium. Indeed, the degree of toxicity of these tested fermentation inhibitors varies with the sole carbon source of the medium. We demonstrate that genome integration of an extra copy of autologous GRE2 with its native promotor substantially improved the toxic tolerance of engineered xylose-fermenting S. cerevisiae to major inhibitory compounds including glycolaldehyde in the xylose-containing medium, and xylose-rich, lignocellulosic hydrolysate derived from Miscanthus giganteus, and concurrently improved the ethanol fermentation profile. Outcomes of this study will aid the development of next-generation robust S. cerevisiae strains for efficient fermentation of hexose and pentose sugars found in biomass hydrolysate.