Microbial CO fixation into lactic acid (LA) is an important approach for low-carbon biomanufacturing. Engineering microbes to utilize CO and sugar as co-substrates can create efficient pathways through input of moderate reducing power to drive CO fixation into product. However, to achieve complete conservation of organic carbon, how to engineer the CO-fixing modules compatible with native central metabolism and merge the processes for improving bioproduction of LA is a big challenge. In this study, we designed and constructed a solar formic acid/pentose (SFAP) pathway in , which enabled CO fixation merging into sugar catabolism to produce LA. In the SFAP pathway, adequate reducing equivalents from formate oxidation drive glucose metabolism shifting from glycolysis to the pentose phosphate pathway. The Rubisco-based CO fixation and sequential reduction of C3 intermediates are conducted to produce LA stoichiometrically. CO fixation theoretically can bring a 20% increase of LA production compared with sole glucose feedstock. This SFAP pathway in the integration of photoelectrochemical cell and an engineered opens an efficient way for fixing CO into value-added bioproducts.

中文翻译：

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在大肠杆菌中设计太阳能甲酸/戊糖 (SFAP) 途径以生产乳酸

微生物将二氧化碳固定为乳酸（LA）是低碳生物制造的重要方法。利用二氧化碳和糖作为共底物的工程微生物可以通过输入适度的还原力来驱动二氧化碳固定到产品中，从而创建有效的途径。然而，为了实现有机碳的完全保存，如何设计与天然中央代谢兼容的固碳模块并融合提高LA生物生产的过程是一个巨大的挑战。在这项研究中，我们设计并构建了一条太阳甲酸/戊糖（SFAP）途径，该途径使CO固定合并到糖分解代谢中以产生LA。在 SFAP 途径中，来自甲酸盐氧化的足够的还原当量驱动葡萄糖代谢从糖酵解转向戊糖磷酸途径。基于 Rubisco 的 CO 固定和 C3 中间体的连续还原可按化学计量生产 LA。理论上，与单一葡萄糖原料相比，CO 固定可以使 LA 产量增加 20%。这种光电化学电池和工程集成的 SFAP 途径为将 CO 固定为增值生物产品开辟了一条有效的途径。