Arantes Ana L, Moreira João P C, Diender Martijn, Parshina Sofiya N, Stams Alfons J M, Alves M Madalena, Alves Joana I, Sousa Diana Z
Laboratory of Microbiology, Wageningen University & Research, Wageningen, Netherlands.
Centre of Biological Engineering, University of Minho, Braga, Portugal.
Front Microbiol. 2020 Jan 31;11:58. doi: 10.3389/fmicb.2020.00058. eCollection 2020.
Syngas is a substrate for the anaerobic bioproduction of fuels and valuable chemicals. In this study, anaerobic sludge was used for microbial enrichments with synthetic syngas and acetate as main substrates. The objectives of this study were to identify microbial networks (in enrichment cultures) for the conversion of syngas to added-value products, and to isolate robust, non-fastidious carboxydotrophs. Enrichment cultures produced methane and propionate, this last one an unusual product from syngas fermentation. A bacterium closely related to was identified as most prevalent (87% relative abundance) in the enrichments. sp. and propionate-producing bacteria clustering within the genera and were also found. Further on, strain JM, was isolated and was found to be 99% identical (16S rRNA gene) to DSM 1911. Digital DNA-DNA hybridization (dDDH) value between the genomes of strain JM and was 77.1%, indicating that strain JM is a new strain of . Strain JM can grow on carbon monoxide (100% CO, total pressure 170 kPa) without yeast extract or formate, producing mainly acetate. Remarkably, conversion of CO by strain JM showed shorter lag phase than in cultures of DSM 1911, and about four times higher amount of CO was consumed in 7 days. Genome analysis suggests that strain JM uses the Wood-Ljungdahl pathway for the conversion of one carbon compounds (CO, formate, CO/H). Genes encoding bifurcational enzyme complexes with similarity to the bifurcational formate dehydrogenase (Fdh) of are present, and possibly relate to the higher tolerance to CO of strain JM compared to other species. DSM 1911 grew on CO in medium containing 1 mM formate.
合成气是用于厌氧生物生产燃料和有价值化学品的底物。在本研究中，厌氧污泥用于以合成气和乙酸盐作为主要底物的微生物富集培养。本研究的目的是确定（富集培养物中的）微生物网络，用于将合成气转化为增值产品，并分离出健壮、非苛求的羧基营养菌。富集培养物产生了甲烷和丙酸盐，后者是合成气发酵中一种不寻常的产物。一种与[未提及具体菌株名称]密切相关的细菌被鉴定为在富集培养物中最为普遍（相对丰度为87%）。还发现了[未提及具体菌株名称]以及在[未提及具体属名]属内聚集的产丙酸盐细菌。此外，分离出了菌株JM，发现其与[未提及具体菌株名称]DSM 1911的16S rRNA基因有99%的同一性。菌株JM和[未提及具体菌株名称]基因组之间的数字DNA - DNA杂交（dDDH）值为77.1%，表明菌株JM是[未提及具体菌株名称]的一个新菌株。菌株JM可以在没有酵母提取物或甲酸盐的情况下，在一氧化碳（100% CO，总压力为170 kPa）上生长，主要产生乙酸盐。值得注意的是，菌株JM对CO的转化显示出比[未提及具体菌株名称]DSM 1911培养物更短的延迟期，并且在7天内消耗的CO量大约高出四倍。基因组分析表明，菌株JM使用伍德 - Ljungdahl途径来转化一碳化合物（CO、甲酸盐、CO/H）。存在与[未提及具体菌株名称]的分叉型甲酸脱氢酶（Fdh）相似的编码分叉型酶复合物的基因，这可能与菌株JM相对于其他[未提及具体菌株名称]物种对CO的更高耐受性有关。[未提及具体菌株名称]DSM 1911在含有1 mM甲酸盐的培养基中在CO上生长。
