Glycolate is a bulk chemical which has been widely used in textile, food processing, and pharmaceutical industries. Glycolate can be produced from sugars by microbial fermentation. However, when using glucose as the sole carbon source, the theoretical maximum carbon molar yield of glycolate is 0.67 mol/mol due to the loss of carbon as CO₂. In this study, a synergetic system for simultaneous utilization of acetate and glucose was designed to increase the carbon yield. The main function of glucose is to provide NADPH while acetate to provide the main carbon backbone for glycolate production. Theoretically, 1 glucose and 5 acetate can produce 6 glycolate, and the carbon molar yield can be increased to 0.75 mol/mol. The whole synthetic pathway was divided into two modules, one for converting acetate to glycolate and another to utilize glucose to provide NADPH. After engineering module I through activation of acs, gltA, aceA and ycdW, glycolate titer increased from 0.07 to 2.16 g/L while glycolate yields increased from 0.04 to 0.35 mol/mol-acetate and from 0.03 to 1.04 mol/mol-glucose. Module II was then engineered to increase NADPH supply. Through deletion of pfkA, pfkB, ptsI and sthA genes as well as upregulating zwf, pgl and tktA, glycolate titer increased from 2.16 to 4.86 g/L while glycolate yields increased from 0.35 to 0.82 mol/mol-acetate and from 1.04 to 6.03 mol/mol-glucose. The activities of AceA and YcdW were further increased to pull the carbon flux to glycolate, which increased glycolate yield from 0.82 to 0.92 mol/mol-acetate. Fed-batch fermentation of the final strain NZ-Gly303 produced 73.3 g/L glycolate with a productivity of 1.04 g/(L·h). The acetate to glycolate yield was 0.85 mol/mol (1.08 g/g), while glucose to glycolate yield was 6.1 mol/mol (2.58 g/g). The total carbon molar yield was 0.60 mol/mol, which reached 80% of the theoretical value.

乙醇酸盐是一种大宗化学品，已广泛用于纺织、食品加工和制药行业。乙醇酸可以通过微生物发酵由糖生产。然而，当使用葡萄糖作为唯一碳源时，由于碳作为 CO ₂的损失，乙醇酸的理论最大碳摩尔产率为 0.67 mol/mol. 在这项研究中，设计了一个同时利用醋酸盐和葡萄糖的协同系统来提高碳产量。葡萄糖的主要功能是提供 NADPH，而乙酸盐则为乙醇酸生产提供主要的碳骨架。理论上，1葡萄糖和5乙酸可生成6乙醇酸，碳摩尔产率可提高到0.75mol/mol。整个合成途径分为两个模块，一个用于将乙酸酯转化为乙醇酸，另一个用于利用葡萄糖提供 NADPH。通过激活acs、gltA、aceA和ycdW工程模块 I 之后，乙醇酸滴度从 0.07 增加到 2.16 g/L，而乙醇酸产量从 0.04 增加到 0.35 mol/mol-乙酸盐和从 0.03 增加到 1.04 mol/mol-葡萄糖。然后设计模块 II 以增加 NADPH 供应。通过删除pfkA、pfkB、ptsI和sthA基因以及上调zwf、pgl和tktA，乙醇酸滴度从 2.16 增加到 4.86 g/L，而乙醇酸产量从 0.35 增加到 0.82 mol/mol-乙酸盐和从 1.04 增加到 6.03 mol/mol-葡萄糖。AceA 和 YcdW 的活性进一步增加以将碳通量拉向乙醇酸，这将乙醇酸产量从 0.82 增加到 0.92 mol/mol-乙酸。最终菌株 NZ-Gly303 的补料分批发酵产生 73.3 g/L 乙醇酸，生产率为 1.04 g/(L · h)。乙酸酯对乙醇酸酯的产率为 0.85 mol/mol (1.08 g/g)，而葡萄糖对乙醇酸酯的产率为 6.1 mol/mol (2.58 g/g)。总碳摩尔收率为0.60 mol/mol，达到理论值的80%。