Department of Chemistry, University of Sheffield, Sheffield S3 7HF, UK.
School of Natural & Environmental Sciences, Newcastle University, Newcastle upon Tyne NE1 7RU, UK.
Microbiology (Reading). 2022 Mar;168(3). doi: 10.1099/mic.0.001167.
is a facultative anaerobe that can grow in a variety of environmental conditions. In the complete absence of O, 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 H 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 H and CO 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 H and CO. Our data support an anion-proton symport model for formic acid transport. In addition, when was grown in a micro-aerobic (micro-oxic) environment it was possible to analyse aspects of formate and O respiration occurring alongside anaerobic metabolism. While cells growing under micro-aerobic conditions generated endogenous formic acid, no H was produced. However, addition of exogenous formate at the outset of cell growth did induce FHL-1 biosynthesis and resulted in formate-dependent H production in the presence of O.
是一种兼性厌氧菌，可以在多种环境条件下生长。在完全没有 O 的情况下， 可以进行混合酸发酵，其中包含甲酸的复杂代谢。在本研究中，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来深入了解细菌的甲酸盐和 H 代谢。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，然后再次被甲酸氢酶（FHL-1）歧化为 H 和 CO。然而，外源性添加的 D 标记甲酸的行为与内源性甲酸完全不同，它被细胞立即独立地、可能通过不同的机制吸收，并转化为 H 和 CO。我们的数据支持甲酸运输的阴离子-质子协同转运模型。此外，当 在微需氧（微氧）环境中生长时，我们可以分析与厌氧代谢同时发生的甲酸盐和 O 呼吸的各个方面。虽然在微需氧条件下生长的细胞会产生内源性甲酸，但不会产生 H。然而，在外源甲酸盐开始添加到细胞生长时，会诱导 FHL-1 的生物合成，并导致在存在 O 的情况下依赖于甲酸盐的 H 产生。
