School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, England, United Kingdom.
Appl Environ Microbiol. 2021 Oct 14;87(21):e0029921. doi: 10.1128/AEM.00299-21. Epub 2021 Sep 8.
Escherichia coli is a Gram-negative bacterium that is a workhorse for biotechnology. The organism naturally performs a mixed-acid fermentation under anaerobic conditions where it synthesizes formate hydrogenlyase (FHL-1). The physiological role of the enzyme is the disproportionation of formate into H and CO. However, the enzyme has been observed to catalyze hydrogenation of CO given the correct conditions, and so it has possibilities in bio-based carbon capture and storage if it can be harnessed as a hydrogen-dependent CO reductase (HDCR). In this study, an E. coli host strain was engineered for the continuous production of formic acid from H and CO during bacterial growth in a pressurized batch bioreactor. Incorporation of tungsten, in place of molybdenum, in FHL-1 helped to impose a degree of catalytic bias on the enzyme. This work demonstrates that it is possible to couple cell growth to simultaneous, unidirectional formate production from carbon dioxide and develops a process for growth under pressurized gases. Greenhouse gas emissions, including waste carbon dioxide, are contributing to global climate change. A basket of solutions is needed to steadily reduce emissions, and one approach is bio-based carbon capture and storage. Here, we present our latest work on harnessing a novel biological solution for carbon capture. The Escherichia coli formate hydrogenlyase (FHL-1) was engineered to be constitutively expressed. Anaerobic growth under pressurized H and CO gases was established, and aqueous formic acid was produced as a result. Incorporation of tungsten into the enzyme in place of molybdenum proved useful in poising FHL-1 as a hydrogen-dependent CO reductase (HDCR).
大肠杆菌是一种革兰氏阴性细菌，是生物技术的得力助手。在厌氧条件下，该生物自然进行混合酸发酵，在此过程中合成甲酸氢酶（FHL-1）。该酶的生理作用是将甲酸歧化为 H 和 CO。然而，在适当的条件下，该酶已被观察到催化 CO 的加氢，因此如果它可以作为依赖氢的 CO 还原酶（HDCR）被利用，它在生物基碳捕获和存储方面具有潜力。在这项研究中，通过工程改造大肠杆菌宿主菌株，使其能够在加压分批生物反应器中生长时，从 H 和 CO 连续生产甲酸。在 FHL-1 中用钨替代钼有助于对酶施加一定程度的催化偏见。这项工作表明，有可能将细胞生长与从二氧化碳中同时进行单向甲酸生产结合起来，并开发出一种在加压气体下生长的工艺。温室气体排放，包括废二氧化碳，正在导致全球气候变化。需要一篮子解决方案来稳定减排，其中一种方法是生物基碳捕获和存储。在这里，我们介绍了我们在利用新型生物解决方案进行碳捕获方面的最新工作。大肠杆菌甲酸氢酶（FHL-1）被设计为组成型表达。在加压 H 和 CO 气体下进行厌氧生长，从而产生水合甲酸。用钨替代钼掺入酶中有助于使 FHL-1 成为依赖氢的 CO 还原酶（HDCR）。
