Department of Civil and Environmental Engineering, University of Alberta, Edmonton, AB, Canada.
Water Environ Res. 2021 Jan;93(1):84-93. doi: 10.1002/wer.1357. Epub 2020 Jun 8.
Propionate is one of the most important intermediates in anaerobic digestion, and its degradation requires a syntrophic partnership between propionate-oxidizing bacteria and hydrogenotrophic methanogens. Anaerobic digestion efficiency can be improved by direct interspecies electron transfer (DIET) through conductive materials. This study aimed to investigate the effects of DIET on syntrophic propionate oxidization under room temperature (20°C) and reveal the syntrophic partners. Firstly, conventional anaerobic consortium and conductive material-enriched consortium were tested for DIET under high H partial pressure. The latter supplemented with granular activated carbon (GAC) can mitigate H inhibition through DIET. Secondly, a DIET consortium was enriched for testing GAC and magnetite, both showed DIET facilitation. Microbial communities in GAC- and magnetite-supplemented reactors were similar. Syntrophic propionate-oxidizing bacteria, for example, Smithella (3.9%-9.9%) and a genus from the family Syntrophaceae (1.9%-3.6%) and methanogens Methanobacterium (30.3%-75.2%), Methanolinea (8.5%-25.2%), Methanosaeta (11.4%-36.7%), and Candidatus Methanofastidiosum (3.6%-6.6%), were predominant. Functional genes for cell mobility and membrane transport (3.3% and 9.5% in control reactor) increased with GAC (3.7% and 11.1%, respectively) and magnetite (3.7% and 10.9%, respectively) addition. Syntrophic propionate-oxidizing bacteria and methanogenesis partners were revealed by co-occurrence network, for example, Methanobacterium with Smithella, Syntrophobacter, Dechloromonas, and Trichococcus, signifying the importance of the syntrophic partnership in DIET environment. PRACTITIONER POINTS: DIET improved syntrophic propionate oxidization under room temperature condition (20°C). Microbial communities were similar for GAC- and magnetite-supplemented reactors, different with control reactor. Syntrophic propionate-oxidizing bacteria and methanogenesis partners were revealed by co-occurrence network. Methanobacterium and Smithella, Syntrophobacter, Dechloromonas, and Trichococcus were correlated.
丙酸是厌氧消化过程中的最重要的中间产物之一，其降解需要丙酸氧化菌和产氢甲烷菌之间的共营养共生关系。通过导电材料的直接种间电子传递（DIET）可以提高厌氧消化效率。本研究旨在探讨 DIET 在室温（20°C）下共营养丙酸氧化中的作用，并揭示共营养伙伴。首先，在高 H 分压下测试了常规厌氧群落和富含导电材料的群落中的 DIET。后者通过添加颗粒活性炭（GAC）可以通过 DIET 缓解 H 抑制。其次，富集 DIET 群落用于测试 GAC 和磁铁矿，两者均显示出 DIET 促进作用。在添加 GAC 和磁铁矿的反应器中的微生物群落相似。共营养丙酸氧化菌，例如 Smithella（3.9%-9.9%）和从Syntrophaceae 科的一个属（1.9%-3.6%）和产甲烷菌 Methanobacterium（30.3%-75.2%）、Methanolinea（8.5%-25.2%）、Methanosaeta（11.4%-36.7%）和 Candidatus Methanofastidiosum（3.6%-6.6%）占主导地位。细胞迁移和膜转运的功能基因（对照反应器中分别为 3.3%和 9.5%）随着 GAC（分别为 3.7%和 11.1%）和磁铁矿（分别为 3.7%和 10.9%）的添加而增加。通过共现网络揭示了共营养丙酸氧化菌和产甲烷作用伙伴，例如 Methanobacterium 与 Smithella、Syntrophobacter、Dechloromonas 和 Trichococcus，表明在 DIET 环境中这种共营养共生关系的重要性。从业者要点：DIET 提高了室温（20°C）条件下的共营养丙酸氧化作用。添加 GAC 和磁铁矿的反应器中的微生物群落与对照反应器相似，而不同。通过共现网络揭示了共营养丙酸氧化菌和产甲烷作用伙伴。Methanobacterium 和 Smithella、Syntrophobacter、Dechloromonas 和 Trichococcus 呈相关性。
