Department of Civil and Environmental Engineering, The University of Tennessee, Knoxville, TN, 37996, USA.
Institute for a Secure and Sustainable Environment, The University of Tennessee, Knoxville, TN, 37996, USA.
Appl Microbiol Biotechnol. 2021 Dec;105(23):8937-8949. doi: 10.1007/s00253-021-11645-9. Epub 2021 Oct 25.
Methanogenesis is central to anaerobic digestion processes. The conversion of propionate as a key intermediate for methanogenesis requires syntrophic interactions between bacterial and archaeal partners. In this study, a series of methanogenic enrichments with propionate as the sole substrate were developed to identify microbial populations specifically involved in syntrophic propionate conversion. These rigorously controlled propionate enrichments exhibited functional stability with consistent propionate conversion and methane production; yet, the methanogenic microbial communities experienced substantial temporal dynamics, which has important implications on the understanding of mechanisms involved in microbial community assembly in anaerobic digestion. Syntrophobacter was identified as the most abundant and consistent bacterial partner in syntrophic propionate conversion regardless of the origin of the source culture, the concentration of propionate, or the temporal dynamics of the culture. In contrast, the methanogen partners involved in syntrophic propionate conversion lacked consistency, as the dominant methanogens varied as a function of process condition and temporal dynamics. Methanoculleus populations were specifically enriched as the syntrophic partner at inhibitory levels of propionate, likely due to the ability to function under unfavorable environmental conditions. Syntrophic propionate conversion was carried out exclusively via transformation of propionate into acetate and hydrogen in enrichments established in this study. Microbial populations highly tolerant of elevated propionate, represented by Syntrophobacter and Methanoculleus, are of great significance in understanding methanogenic activities during process perturbations when propionate accumulation is frequently encountered. Key points • Syntrophobacter was the most consistent bacterial partner in propionate metabolism. • Diverse hydrogenotrophic methanogen populations could serve as syntrophic partners. • Methanoculleus emerged as a methanogen partner tolerant of elevated propionate.
产甲烷作用是厌氧消化过程的核心。丙酸作为产甲烷作用的关键中间产物的转化需要细菌和古菌伙伴之间的协同相互作用。在这项研究中，开发了一系列以丙酸作为唯一底物的产甲烷富集物，以鉴定专门参与协同丙酸转化的微生物种群。这些严格控制的丙酸富集物表现出功能稳定性，具有一致的丙酸转化和甲烷生成；然而，产甲烷微生物群落经历了显著的时间动态变化，这对理解厌氧消化中微生物群落组装所涉及的机制具有重要意义。无论来源培养物的来源、丙酸的浓度或培养物的时间动态如何，Syntrophobacter 都被确定为协同丙酸转化中最丰富和最一致的细菌伙伴。相比之下，参与协同丙酸转化的产甲烷菌伙伴缺乏一致性，因为主要的产甲烷菌随着过程条件和时间动态的变化而变化。Methanoculleus 种群在丙酸的抑制水平下被特别富集为协同伙伴，这可能是由于其在不利环境条件下发挥作用的能力。在本研究中建立的富集物中，协同丙酸转化仅通过将丙酸转化为乙酸和氢气来进行。对高浓度丙酸高度耐受的微生物种群，如 Syntrophobacter 和 Methanoculleus，对于理解丙酸积累时经常出现的过程扰动期间的产甲烷活性具有重要意义。要点 • Syntrophobacter 是丙酸代谢中最一致的细菌伙伴。 • 多种氢营养型产甲烷菌种群可以作为协同伙伴。 • Methanoculleus 作为一种耐受高浓度丙酸的产甲烷菌伙伴出现。
