School of Energy & Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
J Agric Food Chem. 2022 Nov 2;70(43):13913-13921. doi: 10.1021/acs.jafc.2c04621. Epub 2022 Oct 6.
In this study, we evaluated the effects of several metabolic engineering strategies in a systematic and combinatorial manner to enhance the free fatty acid (FFA) production in . The strategies included (i) overexpression of mutant thioesterase I ('TesA) to efficiently release the FFAs from fatty acyl-ACP; (ii) coexpression of global regulatory protein FadR; (iii) heterologous expression of methylmalonyl-CoA carboxyltransferase and phosphoenolpyruvate carboxylase to synthesize fatty acid precursor molecule malonyl-CoA; and (iv) disruption of genes associated with membrane proteins (GusC, MdlA, and EnvR) to improve the cellular state and export the FFAs outside the cell. The synergistic effects of these genetic modifications in strain SBF50 yielded 7.2 ± 0.11 g/L FFAs at the shake flask level. In fed-batch cultivation under nitrogen-limiting conditions, strain SBF50 produced 33.6 ± 0.02 g/L FFAs with a productivity of 0.7 g/L/h from glucose, which is the maximum titer reported in to date. Combinatorial metabolic engineering approaches can prove to be highly useful for the large-scale production of FA-derived chemicals and fuels.
在这项研究中，我们以系统和组合的方式评估了几种代谢工程策略，以提高 在游离脂肪酸 (FFA) 的生产。这些策略包括：（i）过表达突变硫酯酶 I（‘TesA），以有效地从脂肪酸酰基-ACP 中释放 FFAs；（ii）共表达全局调控蛋白 FadR；（iii）异源表达甲基丙二酰辅酶 A 羧化酶和磷酸烯醇丙酮酸羧化酶，以合成脂肪酸前体分子丙二酰辅酶 A；（iv）敲除与膜蛋白相关的基因（GusC、MdlA 和 EnvR），以改善细胞状态并将 FFAs 外排到细胞外。在摇瓶水平上，这些遗传修饰在 SBF50 菌株中的协同作用产生了 7.2 ± 0.11 g/L 的 FFAs。在氮限制条件下的分批补料培养中，SBF50 菌株从葡萄糖中生产了 33.6 ± 0.02 g/L 的 FFAs，比生产能力为 0.7 g/L/h，这是迄今为止 在 中报道的最高产量。组合代谢工程方法可以证明对 FA 衍生化学品和燃料的大规模生产非常有用。
