Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
Key Laboratory of Industrial Ecology and Environmental Engineering (Dalian University of Technology), Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
Water Res. 2016 Oct 1;102:475-484. doi: 10.1016/j.watres.2016.07.005. Epub 2016 Jul 5.
Direct interspecies electron transfer (DIET) has been considered as an alternative to interspecies H2 transfer (IHT) for syntrophic metabolism, but the microorganisms capable of metabolizing the key intermediates, such as propionate and butyrate, via DIET have yet to be described. A strategy of culturing the enrichments with ethanol as a DIET substrate to stimulate the communities for the syntrophic metabolism of propionate and/or butyrate was proposed in this study. The results showed that the syntrophic propionate and/or butyrate degradation was significantly improved in the ethanol-stimulated reactor when propionate/butyrate was the sole carbon source. The conductivity of the ethanol-stimulated enrichments was as 5 folds (for propionate)/76 folds (for butyrate) as that of the traditional enrichments (never ethanol fed). Microbial community analysis revealed that Geobacter species known to proceed DIET were only detected in the ethanol-stimulated enrichments. Together with the significant increase of Methanosaeta and Methanosarcina species in these enrichments, the potential DIET between Geobacter and Methanosaeta or Methanosarcina species might be established to improve the syntrophic propionate and/or butyrate degradation. Further experiments demonstrated that granular activated carbon (GAC) could improve the syntrophic metabolism of propionate and/or butyrate of the ethanol-stimulated enrichments, while almost no effects on the traditional enrichments. Also, the high H2 partial pressure could inhibit the syntrophic propionate and/or butyrate degradation of the traditional enrichments, but its effect on that of the ethanol-stimulated enrichments was negligible.
直接种间电子转移（DIET）已被认为是种间 H2 转移（IHT）的替代方法，用于协同代谢，但能够通过 DIET 代谢关键中间产物（如丙酸和丁酸）的微生物尚未被描述。本研究提出了一种以乙醇作为 DIET 底物培养富集物的策略，以刺激群落进行丙酸和/或丁酸的协同代谢。结果表明，当丙酸/丁酸作为唯一碳源时，乙醇刺激的反应器中丙酸和/或丁酸的协同降解得到了显著改善。乙醇刺激的富集物的电导率比传统富集物（从未添加乙醇）高 5 倍（用于丙酸）/76 倍（用于丁酸）。微生物群落分析表明，已知进行 DIET 的 Geobacter 种仅在乙醇刺激的富集物中检测到。与这些富集物中 Methanosaeta 和 Methanosarcina 种的显著增加一起，Geobacter 和 Methanosaeta 或 Methanosarcina 种之间可能建立了潜在的 DIET，以改善协同丙酸和/或丁酸降解。进一步的实验表明，颗粒活性炭（GAC）可以改善乙醇刺激的富集物中丙酸和/或丁酸的协同代谢，而对传统富集物几乎没有影响。此外，高 H2 分压会抑制传统富集物中丙酸和/或丁酸的协同降解，但对乙醇刺激的富集物的影响可以忽略不计。
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