Department of Microbiology, University of Massachusetts-Amherst, Amherst, Massachusetts, USA.
School of Bioengineering, Dalian University of Technology, Dalian, Liaoning, China.
Appl Environ Microbiol. 2021 Jun 11;87(13):e0073121. doi: 10.1128/AEM.00731-21.
It is known that the physiology of species can differ significantly, but the ecological impact of these differences is unclear. We recovered two strains of from two different ecosystems with a similar enrichment and isolation method. Both strains had the same ability to metabolize organic substrates and participate in direct interspecies electron transfer but also had major physiological differences. Strain DH-1, which was isolated from an anaerobic digester, used H as an electron donor. Genome analysis indicated that it lacks an Rnf complex and conserves energy from acetate metabolism via intracellular H cycling. In contrast, strain DH-2, a subsurface isolate, lacks hydrogenases required for H uptake and cycling and has an Rnf complex for energy conservation when growing on acetate. Further analysis of the genomes of previously described isolates, as well as phylogenetic and metagenomic data on uncultured in anaerobic digesters and diverse soils and sediments, revealed a physiological dichotomy that corresponded with environment of origin. The physiology of type I revolves around H production and consumption. In contrast, type II species eschew H and have genes for an Rnf complex and the multiheme, membrane-bound -type cytochrome MmcA, shown to be essential for extracellular electron transfer. The distribution of species in diverse environments suggests that the type I H-based physiology is well suited for high-energy environments, like anaerobic digesters, whereas type II Rnf/cytochrome-based physiology is an adaptation to the slower, steady-state carbon and electron fluxes common in organic-poor anaerobic soils and sediments. Biogenic methane is a significant greenhouse gas, and the conversion of organic wastes to methane is an important bioenergy process. species play an important role in methane production in many methanogenic soils and sediments as well as anaerobic waste digesters. The studies reported here emphasize that the genus is composed of two physiologically distinct groups. This is important to recognize when interpreting the role of in methanogenic environments, especially regarding H metabolism. Furthermore, the finding that type I species predominate in environments with high rates of carbon and electron flux and that type II species predominate in lower-energy environments suggests that evaluating the relative abundance of type I and type II may provide further insights into rates of carbon and electron flux in methanogenic environments.
已知物种的生理学特征可能存在显著差异,但这些差异对生态的影响尚不清楚。我们使用相似的富集和分离方法,从两个不同的生态系统中回收了两种 。这两种菌株都具有相同的代谢有机底物和参与直接种间电子转移的能力,但也存在主要的生理差异。从厌氧消化器中分离出的菌株 DH-1 以 H 作为电子供体。基因组分析表明,它缺乏 Rnf 复合物,并通过细胞内 H 循环从乙酸盐代谢中保存能量。相比之下,从地下水中分离出的菌株 DH-2 缺乏用于 H 摄取和循环的氢化酶,并且在以乙酸盐为生长基质时具有 Rnf 复合物用于能量保存。对以前描述的分离株的基因组进行进一步分析,以及对厌氧消化器中未培养的 和不同土壤和沉积物中的种间电子传递的系统发育和宏基因组数据进行分析,揭示了与起源环境相对应的生理二分法。I 型 的生理学围绕 H 的产生和消耗展开。相比之下,II 型 物种回避 H,并具有 Rnf 复合物和多血红素、膜结合的 -型细胞色素 MmcA 的基因,这些基因对于细胞外电子传递是必不可少的。 在不同环境中的分布表明,基于 H 的 I 型生理学非常适合高能环境,如厌氧消化器,而基于 Rnf/cytochrome 的 II 型生理学是对有机贫厌氧土壤和沉积物中常见的缓慢、稳态碳和电子通量的适应。生物甲烷是一种重要的温室气体,将有机废物转化为甲烷是一种重要的生物能源过程。 在许多产甲烷土壤和沉积物以及厌氧废物消化器中, 种在甲烷的产生中发挥着重要作用。这里报道的研究强调,属 由两个在生理学上明显不同的群体组成。在解释 在产甲烷环境中的作用时,这一点很重要,尤其是在 H 代谢方面。此外,发现 I 型 物种在碳和电子通量速率较高的环境中占优势,而 II 型 物种在能量较低的环境中占优势,这表明评估 I 型和 II 型 的相对丰度可能会为产甲烷环境中的碳和电子通量速率提供进一步的见解。