Shi Zhijian, Zhang Chao, Sun Meichen, Usman Muhammad, Cui Yong, Zhang Shicheng, Ni Bingjie, Luo Gang
Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai, 200438, China.
Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai, 200438, China.
Environ Res. 2024 Nov 15;261:119717. doi: 10.1016/j.envres.2024.119717. Epub 2024 Aug 2.
Propionate is a model substrate for studying energy-limited syntrophic communities in anaerobic digestion, and syntrophic bacteria usually catalyze its degradation in syntrophy with methanogens. In the present study, metagenomics and metatranscriptomics were used to study the effect of the supportive material (e.g., hydrochar) on the key members of propionate degradation and their cooperation mechanism. The results showed that hydrochar increased the methane production rate (up to 57.1%) from propionate. The general transcriptional behavior of the microbiome showed that both interspecies H transfer (IHT) and direct interspecies electron transfer (DIET) played essential roles in the hydrochar-mediated methanation of propionate. Five highly active syntrophic propionate-oxidizing bacteria were identified by genome-centric metatranscriptomics. H85pel, a member of the family Pelotomaculaceae, was specifically enriched by hydrochar. Hydrochar enhanced the expression of the flagellum subunit, which interacted with methanogens and hydrogenases in H85pel, indicating that IHT was one of the essential factors promoting propionate degradation. Hydrochar also enriched H162tha belonging to the genus of Thauera. Hydrochar induced the expression of genes related to the complete propionate oxidation pathway, which did not produce acetate. Hydrochar and e-pili-mediated DIET were enhanced, which was another factor promoting propionate degradation. These findings improved the understanding of metabolic traits and cooperation between syntrophic propionate oxidizing bacteria (SPOB) and co-metabolizing partners and provided comprehensive transcriptional insights on function in propionate methanogenic systems.
丙酸盐是研究厌氧消化中能量受限的互营群落的模型底物，互营细菌通常与产甲烷菌协同催化其降解。在本研究中，利用宏基因组学和宏转录组学研究了支撑材料（如水炭）对丙酸盐降解关键成员的影响及其合作机制。结果表明，水炭提高了丙酸盐的甲烷产生率（高达57.1%）。微生物群落的总体转录行为表明，种间氢转移（IHT）和直接种间电子转移（DIET）在水炭介导的丙酸盐甲烷化过程中都起着重要作用。通过以基因组为中心的宏转录组学鉴定出五种高活性的互营丙酸盐氧化细菌。Pelotomaculaceae科的成员H85pel被水炭特异性富集。水炭增强了鞭毛亚基的表达，该亚基在H85pel中与产甲烷菌和氢化酶相互作用，表明IHT是促进丙酸盐降解的重要因素之一。水炭还富集了属于Thauera属的H162tha。水炭诱导了与完整丙酸盐氧化途径相关的基因表达，该途径不产生乙酸盐。水炭和电子菌毛介导的DIET增强，这是促进丙酸盐降解的另一个因素。这些发现增进了对互营丙酸盐氧化细菌（SPOB）与共代谢伙伴之间代谢特征和合作的理解，并为丙酸盐产甲烷系统中的功能提供了全面的转录见解。
