代谢通量分析用于验证天然木糖发酵酵母的代谢组数据。
Metabolic flux analysis for metabolome data validation of naturally xylose-fermenting yeasts.
机构信息
Grupo Engenharia de Biocatalisadores, Universidade de Brasília - UnB , Campus Darcy Ribeiro, Instituto de Ciências Biológicas, Bloco K, 1° andar, Asa Norte, Brasilia, 70.790-900, Brazil.
Empresa Brasileira de Pesquisa Agropecuária, EMBRAPA Agroenergia, Brasília-DF, Brazil.
出版信息
BMC Biotechnol. 2019 Aug 5;19(1):58. doi: 10.1186/s12896-019-0548-0.
BACKGROUND
Efficient xylose fermentation still demands knowledge regarding xylose catabolism. In this study, metabolic flux analysis (MFA) and metabolomics were used to improve our understanding of xylose metabolism. Thus, a stoichiometric model was constructed to simulate the intracellular carbon flux and used to validate the metabolome data collected within xylose catabolic pathways of non-Saccharomyces xylose utilizing yeasts.
RESULTS
A metabolic flux model was constructed using xylose fermentation data from yeasts Scheffersomyces stipitis, Spathaspora arborariae, and Spathaspora passalidarum. In total, 39 intracellular metabolic reactions rates were utilized validating the measurements of 11 intracellular metabolites, acquired by mass spectrometry. Among them, 80% of total metabolites were confirmed with a correlation above 90% when compared to the stoichiometric model. Among the intracellular metabolites, fructose-6-phosphate, glucose-6-phosphate, ribulose-5-phosphate, and malate are validated in the three studied yeasts. However, the metabolites phosphoenolpyruvate and pyruvate could not be confirmed in any yeast. Finally, the three yeasts had the metabolic fluxes from xylose to ethanol compared. Xylose catabolism occurs at twice-higher flux rates in S. stipitis than S. passalidarum and S. arborariae. Besides, S. passalidarum present 1.5 times high flux rate in the xylose reductase reaction NADH-dependent than other two yeasts.
CONCLUSIONS
This study demonstrated a novel strategy for metabolome data validation and brought insights about naturally xylose-fermenting yeasts. S. stipitis and S. passalidarum showed respectively three and twice higher flux rates of XR with NADH cofactor, reducing the xylitol production when compared to S. arborariae. Besides then, the higher flux rates directed to pentose phosphate pathway (PPP) and glycolysis pathways resulted in better ethanol production in S. stipitis and S. passalidarum when compared to S. arborariae.
背景
高效利用木糖仍需要对木糖分解代谢有深入的了解。在本研究中，采用代谢通量分析（MFA）和代谢组学方法来深入了解木糖代谢。因此，构建了一个代谢通量模型来模拟细胞内碳通量，并用于验证非酿酒酵母木糖利用酵母的木糖分解代谢途径中收集的代谢组数据。
结果
使用酿酒酵母、Spathaspora arborariae 和 Spathaspora passalidarum 的木糖发酵数据构建了一个代谢通量模型。总共利用了 39 个细胞内代谢反应速率，验证了通过质谱法获得的 11 种细胞内代谢物的测量值。其中，当与计量模型相比时，80%的总代谢物的相关性超过 90%。在细胞内代谢物中，果糖-6-磷酸、葡萄糖-6-磷酸、核酮糖-5-磷酸和苹果酸在三种研究的酵母中得到了验证。然而，磷酸烯醇丙酮酸和丙酮酸这两种代谢物在任何酵母中都无法得到确认。最后，比较了三种酵母的木糖到乙醇的代谢通量。与 S. passalidarum 和 S. arborariae 相比，木糖在 S. stipitis 中的分解代谢通量高两倍。此外，与其他两种酵母相比，S. passalidarum 中木酮糖还原酶反应 NADH 依赖性的通量高 1.5 倍。
结论
本研究展示了一种新的代谢组数据验证策略，并深入了解了天然木糖发酵酵母。与 S. arborariae 相比，S. stipitis 和 S. passalidarum 分别具有三倍和两倍更高的 NADH 辅助 XR 通量，从而减少了木糖醇的产生。此外，与 S. arborariae 相比，S. stipitis 和 S. passalidarum 中的戊糖磷酸途径（PPP）和糖酵解途径的通量更高，导致乙醇产量更高。
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