Hydrogen production in the presence of oxygen by Escherichia coli K-12
Hydrogen production in the presence of oxygen by Escherichia coli K-12
复制标题
大肠杆菌K-12在有氧条件下产氢的研究
DOI：
10.1101/2022.01.11.475878
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发表时间：
2022-01
期刊：
影响因子：
1.5
通讯作者：
George D. Metcalfe;F. Sargent;M. Hippler
中科院分区：
文献类型：
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作者：
George D. Metcalfe;F. Sargent;M. Hippler
大肠杆菌是一种兼性厌氧菌，可以在各种环境条件下生长。在完全缺乏O2的情况下，E.大肠杆菌可以进行混合酸发酵，其中包含甲酸的复杂代谢。在这项研究中，我们使用腔增强拉曼光谱（CERS），FTIR，液体拉曼光谱，同位素标记和分子遗传学的理解细菌甲酸和H2代谢的进展。结果表明，在厌氧（缺氧）条件下，甲酸是内源性产生的，短暂地从细胞中排出，然后再次被甲酸氢解酶（FHL-1）分解为H2和CO2。然而，外源性添加的D-标记的甲酸盐的行为与内源性甲酸盐完全不同，并且被细胞立即、独立地并且可能通过不同的机制吸收并转化为H2和CO2。我们的数据支持甲酸运输的阴离子-质子共输运模型。此外，当E.大肠杆菌生长在微需氧（微氧）环境中，可以分析甲酸和O2呼吸与厌氧代谢一起发生的方面。虽然在微需氧条件下生长的细胞产生内源性甲酸，但不产生H2。然而，在细胞生长开始时添加外源性甲酸确实诱导FHL-1生物合成，并导致在O2存在下甲酸依赖性H2产生。
Escherichia coli is a facultative anaerobe that can grow in a variety of environmental conditions. In the complete absence of O2, E. coli can perform a mixed-acid fermentation that contains within it an elaborate metabolism of formic acid. In this study, we use cavity-enhanced Raman spectroscopy (CERS), FTIR, liquid Raman spectroscopy, isotopic labelling, and molecular genetics to make advances in the understanding of bacterial formate and H2 metabolism. It is shown that, under anaerobic (anoxic) conditions, formic acid is generated endogenously, excreted briefly from the cell, and then taken up again to be disproportionated to H2 and CO2 by formate hydrogenlyase (FHL-1). However, exogenously added D-labelled formate behaves quite differently from the endogenous formate and is taken up immediately, independently, and possibly by a different mechanism, by the cell and converted to H2 and CO2. Our data support an anion-proton symport model for formic acid transport. In addition, when E. coli was grown in a micro-aerobic (micro-oxic) environment it was possible to analyse aspects of formate and O2 respiration occurring alongside anaerobic metabolism. While cells growing under micro-aerobic conditions generated endogenous formic acid, no H2 was produced. However, addition of exogenous formate at the outset of cell growth did induce FHL-1 biosynthesis and resulted in formate-dependent H2 production in the presence of O2.