木糖发酵酒精代谢工程的研究进展

木糖发酵是生物转化木质纤维素产生酒精及其他化工产品最为重要的一环，但自然界中缺少能将上述生物质有效转化为乙醇的微生物菌种. 近年来，根据代谢工程原理，利用基因工程技术对酵母和细菌进行遗传改造，或将木糖代谢途径引入传统的酒精发酵菌酿酒酵母及高酒精产生菌运动发酵单胞菌中，从而拓展其底物利用范围；或使原本可以利用多种糖底物的细菌获得选择性产生酒精的能力，构建了各种不同类型的木糖发酵重组菌株. 虽然这些重组菌株在木糖转化酒精方面均显示出良好的应用前景，但仍存在诸多问题. 有必要在对木糖代谢调控机制深入系统研究的基础上，进一步改造现有菌株，并结合生化工程技术对重组菌株发酵条件进行优化，以实现高效生物转化木质纤维素原料制取乙醇. 本工作介绍了近年来代谢工程改造微生物菌种发酵木糖生产酒精的研究进展.

Metabolic Engineering for Improving Ethanol Fermentation of Xylose by Yeasts and Bacteria

Efficient fermentation of xylose constitutes a major part of successful bioconversion of lignocellulosic biomass for ethanol and other important chemical production, but there is no natural microorganism suitable for efficiently transforming the renewable lignocellulosic materials. For the last two decades, many improvements have been made in the metabolic engineering of yeasts and bacteria including Zymomonas mobilis and Escherichia coli for the fermentation of xylose to selectively produce ethanol through introducing either xylose metabolic genes or ethanol production genes into the above hosts and a serial of recombinant strains have since been constructed. Although some of them have shown great promise for industrial exploitation, there still remain a lot of problems to be addressed. It seems necessary to make further improvements on the present strains on the basis of systematically learning more about the factors that control xylose metabolism. It also requires that the fermentation of recombinant strains be maximally optimized through biochemical engineering to achieve the bioconversion of lignocellulosic biomass into ethanol with high efficiency. The present review tries to outline some major efforts for developing microbial strains to efficiently ferment xylose to ethanol through metabolic engineering.