Department of Environmental Science and Engineering, Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Fudan University, Shanghai, China.
Shanghai Municipal Engineering Design Institute (Group) Co., Ltd., Shanghai, China.
Appl Environ Microbiol. 2024 Feb 21;90(2):e0204723. doi: 10.1128/aem.02047-23. Epub 2024 Jan 11.
The rapid degradation of short-chain fatty acids (SCFAs) is an essential issue of anaerobic digestion (AD), in which SCFA oxidizers could generally metabolize in syntrophy with methanogens. The dynamic responses of active metagenome-assembled genomes to low concentrations of propionate and acetate were analyzed to identify specific syntrophic SCFA oxidizers and their metabolic characteristics in continuous-flow AD systems treating waste activated sludge with and without hydrochar. In this study, hydrochar increased methane production by 19%, possibly due to hydrochar enhancing acidification and methanogenesis processes. A putative syntrophic propionate oxidizer and two acetate oxidizers contributed substantially to the syntrophic degradation of SCFAs, and hydrochar positively regulated their functional gene expressions. A significant relationship was established between the replication rate of SCFA oxidizers and their stimulation-related transcriptional activity. Acetate was degraded in the hydrochar group, which might be mainly through the syntrophic acetate oxidizer from the genus and methanogens from the genus .IMPORTANCEShort-chain fatty acid (SCFA) degradation is an important process in the methanogenic ecosystem. However, current knowledge of this microbial mechanism is mainly based on studies on a few model organisms incubated as mono- or co-cultures or in enrichments, which cannot provide appropriate evidence in complex environments. Here, this study revealed the microbial mechanism of a hydrochar-mediated anaerobic digestion (AD) system promoting SCFA degradation at the species level and identified key SCFA oxidizing bacteria. Our analysis provided new insights into the SCFA oxidizers involved in the AD of waste activated sludge facilitated by hydrochar.
短链脂肪酸（SCFA）的快速降解是厌氧消化（AD）的一个重要问题，其中 SCFA 氧化菌通常可以与产甲烷菌共生代谢。本研究分析了活性宏基因组组装基因组对低浓度丙酸和乙酸的动态响应，以鉴定连续流 AD 系统中特定的共生 SCFA 氧化菌及其代谢特性，该系统处理有和没有水热炭的活性污泥。在这项研究中，水热炭将甲烷产量提高了 19%，这可能是由于水热炭增强了酸化和产甲烷过程。一种假定的共生丙酸氧化菌和两种乙酸氧化菌对 SCFA 的共生降解做出了重大贡献，水热炭正向调节它们的功能基因表达。SCFA 氧化菌的复制率与它们的刺激相关转录活性之间存在显著关系。在水热炭组中降解了乙酸，这可能主要是通过属中的共生乙酸氧化菌和属中的产甲烷菌。
短链脂肪酸（SCFA）降解是产甲烷生态系统中的一个重要过程。然而，目前关于这一微生物机制的知识主要基于在单培养或共培养或富集物中对少数模式生物的研究，在复杂环境中不能提供适当的证据。在这里，本研究在种水平上揭示了水热炭介导的厌氧消化（AD）系统促进 SCFA 降解的微生物机制，并鉴定了关键的 SCFA 氧化细菌。我们的分析为水热炭促进的活性污泥 AD 中涉及的 SCFA 氧化菌提供了新的见解。
