Santala Suvi, Santala Ville, Liu Nian, Stephanopoulos Gregory
Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
Faculty of Engineering and Natural Sciences, Tampere University, Tampere, Finland.
Biotechnol Bioeng. 2021 Jun;118(6):2283-2292. doi: 10.1002/bit.27740. Epub 2021 Mar 25.
Microbial storage compounds, such as wax esters (WE), are potential high-value lipids for the production of specialty chemicals and medicines. Their synthesis, however, is strictly regulated and competes with cell growth, which leads to trade-offs between biomass and product formation. Here, we use metabolic engineering and synergistic substrate cofeeding to partition the metabolism of Acinetobacter baylyi ADP1 into two distinct modules, each dedicated to cell growth and WE biosynthesis, respectively. We first blocked the glyoxylate shunt and upregulated the WE synthesis pathway to direct the acetate substrate exclusively for WE synthesis, then we controlled the supply of gluconate so it could be used exclusively for cell growth and maintenance. We show that the two modules are functionally independent from each other, allowing efficient lipid accumulation while maintaining active cell growth. Our strategy resulted in 7.2- and 4.2-fold improvements in WE content and productivity, respectively, and the product titer was enhanced by 8.3-fold over the wild type strain. Notably, during a 24-h cultivation, a yield of 18% C-WE/C-total-substrates was achieved, being the highest reported for WE biosynthesis. This study provides a simple, yet powerful, means of controlling cellular operations and overcoming some of the fundamental challenges in microbial storage lipid production.
微生物储存化合物，如蜡酯（WE），是生产特种化学品和药物的潜在高价值脂质。然而，它们的合成受到严格调控，并与细胞生长相互竞争，这导致生物量和产物形成之间的权衡。在此，我们利用代谢工程和协同底物共进料将拜氏不动杆菌ADP1的代谢分为两个不同的模块，每个模块分别专门用于细胞生长和WE生物合成。我们首先阻断乙醛酸循环并上调WE合成途径，以将乙酸盐底物专门导向WE合成，然后我们控制葡萄糖酸盐的供应，使其仅用于细胞生长和维持。我们表明这两个模块在功能上相互独立，在保持活跃细胞生长的同时允许高效的脂质积累。我们的策略分别使WE含量和生产率提高了7.2倍和4.2倍，产物滴度比野生型菌株提高了8.3倍。值得注意的是，在24小时培养过程中，实现了18% C-WE/C-总底物的产率，这是WE生物合成报道的最高产率。这项研究提供了一种简单而有效的控制细胞操作的方法，并克服了微生物储存脂质生产中的一些基本挑战。
