College of Food Science and Technology, Nanjing Agricultural University, Nanjing, Jiangsu 210095, China.
Institute of Agro-Product Processing, Jiangsu Academy of Agricultural Sciences, Nanjing, Jiangsu 210095, China.
Food Chem. 2019 Jan 30;272:628-634. doi: 10.1016/j.foodchem.2018.08.102. Epub 2018 Aug 23.
Medium-chain fatty acids (C-C, MCFAs) represent valuable molecules for food and pharmaceutical industries. However, MCFAs in Escherichia coli induce stresses and toxicity, reducing final yields. These phenotypes could be alleviated if MCFA export from cells was accelerated, yet information on proteins responsible for exporting MCFAs remains limited. Here, a panel of 17 genes or operons was screened. Overexpressing resistance nodulation cell division family transporter acrE, mdtE and mdtC increased MCFA titer by 46.4%, 65.2% and 33.8%, whereas overexpressing transcriptional activators soxS, marA and multidrug efflux pumps cmr, fadL decreased MCFA titer by 42.5%, 27.8%, 37.6% and 29.5%, respectively. Furthermore, the effect of multiple transporter engineering was investigated. Overexpressing acrE, mdtE and mdtC together with deleting cmr increased MCFA production by more than two-fold. This study demonstrated the efficient efflux pump specifically for MCFAs and this multiple transporter engineering strategy can be employed to synthesize other bio-products toxic to microorganisms.
中链脂肪酸（C-C，MCFAs）是食品和制药行业的有价值的分子。然而，大肠杆菌中的 MCFAs 会引起应激和毒性，降低最终产量。如果能加速 MCFA 从细胞中的输出，这些表型可能会得到缓解，但负责出口 MCFAs 的蛋白质的信息仍然有限。在这里，筛选了一组 17 个基因或操纵子。过表达抗性结节细胞分裂家族转运蛋白 acrE、mdtE 和 mdtC 将 MCFA 滴度分别提高了 46.4%、65.2%和 33.8%，而过表达转录激活因子 soxS、marA 和多药外排泵 cmr、fadL 则使 MCFA 滴度分别降低了 42.5%、27.8%、37.6%和 29.5%。此外，还研究了多种转运蛋白工程的效果。过表达 acrE、mdtE 和 mdtC 并同时删除 cmr 使 MCFA 产量增加了两倍以上。本研究证明了针对 MCFAs 的高效外排泵，并且这种多转运蛋白工程策略可用于合成对微生物有毒的其他生物产物。
