Acetogenic bacteria are a diverse group of anaerobes that use the reductive acetyl coenzyme A (acetyl-CoA) (Wood-Ljungdahl) pathway for CO₂ fixation and energy conservation. The conversion of 2 mol CO₂ into acetyl-CoA by using the Wood-Ljungdahl pathway as the terminal electron accepting process is the most prominent metabolic feature for these microorganisms. However, here, we describe that the fecal acetogen Clostridium bovifaecis strain BXX displayed poor metabolic capabilities of autotrophic acetogenesis, and acetogenic utilization of glucose occurred only with the supplementation of formate. Genome analysis of Clostridium bovifaecis revealed that it contains almost the complete genes of the Wood-Ljungdahl pathway but lacks the gene encoding formate dehydrogenase, which catalyzes the reduction of CO₂ to formate as the first step of the methyl branch of the Wood-Ljungdahl pathway. The lack of a gene encoding formate dehydrogenase was verified by PCR, reverse transcription-PCR analysis, enzyme activity assay, and its formate-dependent acetogenic utilization of glucose on DNA, RNA, protein, and phenotype level, respectively. The lack of a formate dehydrogenase gene may be associated with the adaption to a formate-rich intestinal environment, considering the isolating source of strain BXX. The formate-dependent acetogenic growth of Clostridium bovifaecis provides insight into a unique metabolic feature of fecal acetogens.

中文翻译：

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粪便产乙酸梭菌梭状芽胞杆菌对葡萄糖的依赖于形态的产乙酸。

产乙酸细菌是多种厌氧菌，它们使用还原性乙酰辅酶A（acetyl-CoA）（Wood-Ljungdahl）途径固定CO ₂和节约能源。通过Wood-Ljungdahl途径作为末端电子接受过程，将2 mol CO ₂转化为乙酰-CoA是这些微生物最突出的代谢特征。然而，在这里，我们描述了粪便产乙酸牛产梭状芽胞杆菌菌株BXX表现出自养产乙酸不良的代谢能力，并且仅在补充甲酸的情况下才发生了葡萄糖的产乙酸利用。牛津梭菌的基因组分析揭示了它几乎包含了伍德-隆德尔通道的完整基因，但是缺少编码甲酸脱氢酶的基因，该酶催化CO ₂还原为甲酸，这是伍德-隆达尔通道的甲基分支的第一步。通过PCR，逆转录-PCR分析，酶活性测定及其在DNA，RNA，蛋白质和表型水平上对葡萄糖的甲酸依赖性产乙酸利用，分别证实了缺少编码甲酸脱氢酶的基因。考虑到菌株BXX的分离来源，缺少甲酸脱氢酶基因可能与对富含甲酸的肠环境的适应有关。牛津梭菌的甲酸依赖性产乙酸生长 提供对粪便乙酸原独特代谢功能的洞察。