Fermentation of xylose causes inefficient metabolic state due to carbon/energy starvation and reduced glycolytic flux in recombinant industrial Saccharomyces cerevisiae.
Fermentation of xylose causes inefficient metabolic state due to carbon/energy starvation and reduced glycolytic flux in recombinant industrial Saccharomyces cerevisiae.
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DOI：
10.1371/journal.pone.0069005
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Hoshino T
中科院分区：
文献类型：
--
作者：
Matsushika A;Nagashima A;Goshima T;Hoshino T
本研究对重组葡萄糖/木糖共发酵菌株S.在发酵过程中使用不同的碳源，包括葡萄糖、木糖或葡萄糖/木糖混合物，对酿酒酵母菌株MA-R4进行发酵。使用毛细管电泳飞行时间质谱法来确定来自中心碳途径、能量代谢途径的细胞内代谢物库以及二十种氨基酸的水平。当木糖而不是葡萄糖被MA-R4代谢时，糖酵解代谢物包括3-磷酸甘油酸、2-磷酸甘油酸、磷酸烯醇丙酮酸和丙酮酸显著减少，而相反，大多数戊糖磷酸途径代谢物如景天庚酮糖7-磷酸和核酮糖5-磷酸大大增加。这些结果表明，糖酵解的低代谢活性和戊糖磷酸途径中间产物库是木糖利用的潜在限制因素。进一步证明，在木糖发酵期间，二十种氨基酸中的约一半下降，并且腺苷酸/鸟苷酸能荷由于显著降低的三磷酸腺苷/单磷酸腺苷和三磷酸鸟苷/单磷酸鸟苷比率而受到影响，这意味着木糖的发酵导致生物合成能力和能量平衡严重受损的低效代谢状态。此外，单独用木糖发酵显著增加了三羧酸循环中柠檬酸盐的水平，并增加了芳香族氨基酸色氨酸和酪氨酸，强烈支持了诱导碳饥饿的观点。有趣的是，单独用木糖发酵也增加了多胺亚精胺及其前体S-腺苷甲硫氨酸的合成。因此，碳底物的差异，包括发酵培养基中的葡萄糖和木糖，强烈影响MA-R4的动态代谢。这些结果提供了一个代谢的木糖相比，葡萄糖的低乙醇生产率的解释。
In the present study, comprehensive, quantitative metabolome analysis was carried out on the recombinant glucose/xylose-cofermenting S. cerevisiae strain MA-R4 during fermentation with different carbon sources, including glucose, xylose, or glucose/xylose mixtures. Capillary electrophoresis time-of-flight mass spectrometry was used to determine the intracellular pools of metabolites from the central carbon pathways, energy metabolism pathways, and the levels of twenty amino acids. When xylose instead of glucose was metabolized by MA-R4, glycolytic metabolites including 3- phosphoglycerate, 2- phosphoglycerate, phosphoenolpyruvate, and pyruvate were dramatically reduced, while conversely, most pentose phosphate pathway metabolites such as sedoheptulose 7- phosphate and ribulose 5-phosphate were greatly increased. These results suggest that the low metabolic activity of glycolysis and the pool of pentose phosphate pathway intermediates are potential limiting factors in xylose utilization. It was further demonstrated that during xylose fermentation, about half of the twenty amino acids declined, and the adenylate/guanylate energy charge was impacted due to markedly decreased adenosine triphosphate/adenosine monophosphate and guanosine triphosphate/guanosine monophosphate ratios, implying that the fermentation of xylose leads to an inefficient metabolic state where the biosynthetic capabilities and energy balance are severely impaired. In addition, fermentation with xylose alone drastically increased the level of citrate in the tricarboxylic acid cycle and increased the aromatic amino acids tryptophan and tyrosine, strongly supporting the view that carbon starvation was induced. Interestingly, fermentation with xylose alone also increased the synthesis of the polyamine spermidine and its precursor S-adenosylmethionine. Thus, differences in carbon substrates, including glucose and xylose in the fermentation medium, strongly influenced the dynamic metabolism of MA-R4. These results provide a metabolic explanation for the low ethanol productivity on xylose compared to glucose.
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影响因子：
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作者：
Hasunuma T;Sanda T;Yamada R;Yoshimura K;Ishii J;Kondo A
通讯作者：
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作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
ATKINSON, DE