Systematic Engineering of Escherichia coli for d-Lactate Production from Crude Glycerol

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• 作者：Zei Wen Wang ; Mukesh Saini ; Li-Jen Lin ; Chung-Jen Chiang ; Yun-Peng Chao
• 刊名：Journal of Agricultural and Food Chemistry
• 出版年：2015
• 出版时间：November 4, 2015
• 年：2015
• 卷：63
• 期：43
• 页码：9583-9589
• 全文大小：320K
• ISSN：1520-5118

文摘

Crude glycerol resulting from biodiesel production is an abundant and renewable resource. However, the impurities in crude glycerol usually make microbial fermentation problematic. This issue was addressed by systematic engineering of Escherichia coli for the production of d-lactate from crude glycerol. First, mgsA and the synthetic pathways of undesired products were eliminated in E. coli, rendering the strain capable of homofermentative production of optically pure d-lactate. To direct carbon flux toward d-lactate, the resulting strain was endowed with an enhanced expression of glpD鈥?i>glpK in the glycerol catabolism and of a heterologous gene encoding d-lactate dehydrogenase. Moreover, the strain was evolved to improve its utilization of cruder glycerol and subsequently equipped with the FocA channel to export intracellular d-lactate. Finally, the fed-batch fermentation with two-phase culturing was carried out with a bioreactor. As a result, the engineered strain enabled production of 105 g/L d-lactate (99.9% optical purity) from 121 g/L crude glycerol at 40 h. The result indicates the feasibility of our approach to engineering E. coli for the crude glycerol-based fermentation.