As the simplest hydroxyl acid,lactic acid is one of the most important organic acids in food, pharmaceutical,cosmetic and chemical industries.More importantly,it is used to produce polylactic acid (PLA),a biodegradable polymer of great interest because it can be produced from renewable means and biodegradable in nature. Presently, lactic acid can be synthesized either chemically or by microbial fermentation. However, microbial fermentation has some potential advantages in using renewable substrates,high optical purity and environmentally friendly process. There are many strains capable of producing lactic acid such as Escherichia coli, Lactobacillus, Bacillus coagulans and Corynebacterium glutamicum.Owing to a rapid doubling time and growth rate,and the availability of excellent genetic tools for strain improvement,E. coli strains have been developed for effective production of D- and L-lactic acid using a metabolic engineering approach. This review describes the physicochemical properties of lactic acid as well as the state of its research and application. Furthermore,we focus on recent efforts devoted to metabolic engineering of E.coli for the production of lactic acid. Also,this review presents the guidelines for further developments in lactic acid production using E.coli.%乳酸是自然界中最小的手性分子,广泛应用于食品、医药和化工等领域,同时也是合成生物可降解塑料——聚乳酸的前体.目前,化学合成法和微生物发酵法是生产乳酸的两种主要方法,而后者在底物的可再生性、产物光学纯度和环境友好等方面均具有潜在优势.自然界中许多微生物细胞都能合成和积累乳酸,如大肠杆菌、酿酒酵母和乳酸菌等.与乳酸菌、芽胞乳杆菌和谷氨酸棒状杆菌等乳酸生产菌株相比,大肠杆菌具有生长速度快、营养要求简单、易于高密度发酵、代谢网络清楚、遗传操作方法成熟和产物乳酸光学纯度高等优势.本文中,笔者介绍了乳酸的研究现状及其在工业生产领域中的作用,系统综述了国内外通过代谢工程改造大肠杆菌生产乳酸的研究进展,在此基础上展望了乳酸生产研究的发展方向,以期为其工业应用提供参考.
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