Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore, Singapore.
Biotechnol Bioeng. 2011 Mar;108(3):655-65. doi: 10.1002/bit.22965. Epub 2010 Nov 10.
Bioethanol has been recognized as a potential alternative energy source. Among various ethanol-producing microbes, Zymomonas mobilis has acquired special attention due to its higher ethanol yield and tolerance. However, cellular metabolism in Z. mobilis remains unclear, hindering its practical application for bioethanol production. To elucidate such physiological characteristics, we reconstructed and validated a genome-scale metabolic network (iZM363) of Z. mobilis ATCC31821 (ZM4) based on its annotated genome and biochemical information. The phenotypic behaviors and metabolic states predicted by our genome-scale model were highly consistent with the experimental observations of Z. mobilis ZM4 strain growing on glucose as well as NMR-measured intracellular fluxes of an engineered strain utilizing glucose, fructose, and xylose. Subsequent comparative analysis with Escherichia coli and Saccharomyces cerevisiae as well as gene essentiality and flux coupling analyses have also confirmed the functional role of pdc and adh genes in the ethanologenic activity of Z. mobilis, thus leading to better understanding of this natural ethanol producer. In future, the current model could be employed to identify potential cell engineering targets, thereby enhancing the productivity of ethanol in Z. mobilis.
生物乙醇已被视为一种有潜力的替代能源。在各种生产乙醇的微生物中，运动发酵单胞菌由于其更高的乙醇产量和耐受性而受到特别关注。然而，运动发酵单胞菌的细胞代谢仍不清楚，这阻碍了其在生物乙醇生产中的实际应用。为了阐明这些生理特性，我们基于其注释基因组和生化信息，重建并验证了运动发酵单胞菌 ATCC31821（ZM4）的基因组规模代谢网络（iZM363）。我们的基因组规模模型预测的表型行为和代谢状态与运动发酵单胞菌 ZM4 菌株在葡萄糖上生长的实验观察以及利用葡萄糖、果糖和木糖的工程菌株的 NMR 测量的细胞内通量高度一致。随后与大肠杆菌和酿酒酵母的比较分析以及基因必需性和通量耦合分析也证实了 pdc 和 adh 基因在运动发酵单胞菌乙醇生成能力中的功能作用，从而更好地理解了这种天然乙醇生产菌。在未来，该模型可以用于鉴定潜在的细胞工程靶点，从而提高运动发酵单胞菌中乙醇的产量。
