Shen Yu, Wang Ying, Bao Xiao-Ming, Qu Yin-Bo
State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China.
Sheng Wu Gong Cheng Xue Bao. 2003 Sep;19(5):636-40.
Pathway engineering was the third generation of gene engineering. Its main goals were to change metabolic flux and open a new metabolic pathway in organism. Application of recombinant DNA methods to restructure metabolic networks can improve production of metabolite and protein products by altering pathway distributions and rates. Ethanol is the most advanced liquid fuel because it is environmentally friendly. Enhancing fuel ethanol production will require developing lower-cost feedstock, and only lignocellulosic feedstock is available in sufficient quantities to substitute for corn starch. Xylose is the major pentose found in lignocellulosic materials and after glucose the most abundant sugar available in nature. Recently a lot of attentions have been focused on designing metabolic pathway of Saccharomyces cerevisiae in order to expand the substrate of ethanol fermentation, because it is a traditional ethanol producing strain and has wonderful properties for ethanol industry. However, it can not utilize xylose but convert the isomer, xylulose. Many attempts are based on introducing the genes in the pathway of xylose metabolism. The further research includes overexpressing the key enzyme or decreasing the unimportant flux. The sugars in lignocellulose hydrolyzates, therefore, could be efficiently utilized. Here, we describe the ethanol pathway engineering progress in ethanol fermentation from xylose with recombinant Saccharomyces cerevisiae.
途径工程是第三代基因工程。其主要目标是改变代谢通量并在生物体中开辟新的代谢途径。应用重组DNA方法来重构代谢网络，可以通过改变途径分布和速率来提高代谢产物和蛋白质产品的产量。乙醇是最先进的液体燃料，因为它对环境友好。提高燃料乙醇产量需要开发成本更低的原料，而只有木质纤维素原料有足够的数量可替代玉米淀粉。木糖是木质纤维素材料中主要的戊糖，是继葡萄糖之后自然界中含量最丰富的糖类。最近，许多注意力都集中在设计酿酒酵母的代谢途径上，以便扩大乙醇发酵的底物范围，因为它是传统的乙醇生产菌株，对乙醇工业具有优良特性。然而，它不能利用木糖，而是将其转化为木酮糖。许多尝试都是基于引入木糖代谢途径中的基因。进一步的研究包括过表达关键酶或减少不重要的通量。因此，木质纤维素水解产物中的糖类可以得到有效利用。在此，我们描述了利用重组酿酒酵母从木糖发酵生产乙醇的途径工程进展。
