School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
Biotechnol Bioeng. 2012 Jan;109(1):110-5. doi: 10.1002/bit.23311. Epub 2011 Aug 31.
The high price of petroleum-based diesel fuel has led to the development of alternative fuels, such as ethanol. Saccharomyces cerevisiae was metabolically engineered to utilize glycerol as a substrate for ethanol production. For the synthesis of fatty acid ethyl esters (FAEEs) by engineered S. cerevisiae that utilize glycerol as substrate, heterologous expression of an unspecific acyltransferase from Acinetobacter baylyi with glycerol utilizing genes was established. As a result, the engineered YPH499 (pGcyaDak, pGupWs-DgaTCas) strain produced 0.24 g/L FAEEs using endogenous ethanol produced from glycerol. And this study also demonstrated the possibility of increasing FAEE production by enhancing ethanol production by minimizing the synthesis of glycerol. The overall FAEE production in strain YPH499 fps1Δ gpd2Δ (pGcyaDak, pGupWs-DgaTCas) was 2.1-fold more than in YPH499 (pGcyaDak, pGupWs-DgaTCas), with approximately 0.52 g/L FAEEs produced, while nearly 17 g/L of glycerol was consumed. These results clearly indicated that FAEEs were synthesized in engineered S. cerevisiae by esterifying exogenous fatty acids with endogenously produced ethanol from glycerol. This microbial system acts as a platform in applying metabolic engineering that allows the production of FAEEs from cheap and abundant substrates specifically glycerol through the use of endogenous bioethanol.
高油价导致了替代燃料的发展，如乙醇。酿酒酵母被代谢工程改造为利用甘油作为乙醇生产的底物。为了通过工程化酿酒酵母利用甘油作为底物合成脂肪酸乙酯（FAEEs），建立了异源表达来自不动杆菌的非特异性酰基转移酶与甘油利用基因。结果，工程化的 YPH499（pGcyaDak，pGupWs-DgaTCas）菌株利用甘油产生的内源性乙醇生产了 0.24 g/L 的 FAEEs。本研究还通过最小化甘油合成来增强乙醇生产，从而增加 FAEE 产量的可能性。在菌株 YPH499 fps1Δ gpd2Δ（pGcyaDak，pGupWs-DgaTCas）中，总的 FAEE 产量比 YPH499（pGcyaDak，pGupWs-DgaTCas）高出 2.1 倍，产生了约 0.52 g/L 的 FAEEs，而消耗了近 17 g/L 的甘油。这些结果清楚地表明，FAEEs 是通过将外源性脂肪酸与甘油产生的内源性乙醇酯化在工程化酿酒酵母中合成的。该微生物系统作为一个平台，通过利用内源性生物乙醇，从廉价且丰富的甘油等底物生产 FAEEs，应用代谢工程。
