Beijing Bioprocess Key Laboratory, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, PR China.
Enzyme Microb Technol. 2013 Jul 10;53(2):128-33. doi: 10.1016/j.enzmictec.2013.03.012. Epub 2013 Mar 31.
Microbial biosynthesis of fatty acid-derived biofuels from renewable carbon sources has attracted significant attention in recent years. Free fatty acids (FFAs) can be used as precursors for the production of micro-diesel. The expression of codon optimized two plants (Umbellularia californica and Cinnamomum camphora) medium-chain acyl-acyl carrier protein (ACP) thioesterase genes (ucFatB and ccFatB) in Escherichia coli resulted in a very high level of extractable medium-chain-specific hydrolytic activity and caused large accumulation of medium-chain free fatty acids. By heterologous co-expression of acyl-coenzyme A:diacylglycerol acyltransferase from Acinetobacter baylyi ADP1, specific plant thioesterases in E. coli, with supplementation of exogenous ethanol, resulted in drastic changes in fatty acid ethyl esters (FAEEs) composition ranging from 12:0 to 18:1. Through an optimized microbial shake-flask fermentation of two modified E. coli strains, yielded FFAs and FAEEs in the concentration of approximately 500 mg L(-1)/250 mg L(-1) and 2.01 mg g(-1)/1.99 mg g(-1), respectively. The optimal ethanol level for FAEEs yield in the two recombinant strains was reached at the 3% ethanol concentration, which was about 5.4-fold and 1.93-fold higher than that of 1% ethanol concentration.
近年来，从可再生碳源微生物生物合成脂肪酸衍生生物燃料引起了人们的极大关注。游离脂肪酸（FFAs）可用作生产微柴油的前体。对来自加利福尼亚熊果树和樟科植物的两种植物（Umbellularia californica 和 Cinnamomum camphora）的密码子优化的中链酰基辅酶 A 酰基载体蛋白（ACP）硫酯酶基因（ucFatB 和 ccFatB）进行大肠杆菌表达，导致可提取的中链特异性水解活性非常高，并导致中链游离脂肪酸的大量积累。通过异源共表达来自不动杆菌 ADP1 的酰基辅酶 A：二酰基甘油酰基转移酶，以及在大肠杆菌中补充外源性乙醇，导致脂肪酸乙酯（FAEEs）组成发生剧烈变化，从 12:0 到 18:1。通过优化两种改良大肠杆菌菌株的微生物摇瓶发酵，得到的 FFAs 和 FAEEs 浓度分别约为 500mg/L 和 2.01mg/g。两种重组菌株中 FAEEs 产量的最佳乙醇水平在 3%乙醇浓度时达到，比 1%乙醇浓度时高约 5.4 倍和 1.93 倍。
