Deciphering relationships between sulfate-reducing bacteria (SRB) and other microorganisms is crucial for stable operation of anaerobic digestion systems when treating sulfate-containing wastewater. However, few studies have differentiated the incomplete oxidizing SRB (IO-SRB) and complete oxidizing SRB (CO-SRB) in anaerobic digestion ecosystems. Four ethanol-fed bioreactors were operated under two operational modes (sequencing batch reactor, SBR; and continuous-flow reactor, CFR) and two chemical oxygen demand (COD) to sulfate ratios (1 and 2) to systematically explore strategies for enriching IO-SRB and/or CO-SRB and their microbial interactions with other microorganisms. Compared to SBRs, CFRs could enhance sulfate removal and demonstrated higher microbial activities in sulfate and ethanol degradation. IO-SRB competed with ethanol oxidizing bacteria in all reactors, and IO-SRB's contribution to ethanol degradation increased from 62.9 %-67.1 % to 69.0 %-82.1 % as the COD/sulfate ratio decreased from 2 to 1. Moreover, CO-SRB competed acetotrophic methanogens exclusively in CFRs, as CO-SRB could not be efficiently enriched in SBRs. Low COD/sulfate ratios facilitated the enrichment of Desulfococcus (CO-SRB), and the CFR operational mode further strengthened its enrichment. Additionally, hydrogenotrophic SRB outperformed hydrogenotrophic methanogens in all four reactors. In general, IO-SRB and CO-SRB possessed distinct microbial interactions with methanogens, with potential syntrophic relationships between IO-SRB and acetotrophic methanogens while competitive relationships between CO-SRB and acetotrophic methanogens.

中文翻译：

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富集目标硫酸盐还原细菌并揭示它们在厌氧消化生态系统中的微生物相互作用的策略


在处理含硫酸盐的废水时，破译硫酸盐还原细菌 （SRB） 和其他微生物之间的关系对于厌氧消化系统的稳定运行至关重要。然而，很少有研究区分厌氧消化生态系统中的不完全氧化 SRB （IO-SRB） 和完全氧化 SRB （CO-SRB）。四个乙醇进料生物反应器在两种操作模式（序批式反应器，SBR;和连续流反应器，CFR）和两种化学需氧量 （COD） 与硫酸盐的比率（1 和 2）下运行，以系统地探索富集 IO-SRB 和/或 CO-SRB 及其微生物与其他微生物相互作用的策略。与 SBR 相比，CFRs 可以增强硫酸盐去除，并在硫酸盐和乙醇降解中表现出更高的微生物活性。IO-SRB 在所有反应器中都与乙醇氧化菌竞争，随着 COD/硫酸根离子比从 2 降低到 1，IO-SRB 对乙醇降解的贡献从 62.9 %-67.1 % 增加到 69.0 %-82.1 %。此外，由于 CO-SRB 不能在 SBR 中有效富集，因此 CO-SRB 仅在 CFR 中竞争乙酰营养型产甲烷菌。低 COD/硫酸盐比率促进了脱硫球菌 （CO-SRB） 的富集，CFR 操作模式进一步加强了其富集。此外，氢营养型 SRB 在所有四个反应器中的性能都优于氢营养型产甲烷菌。一般来说，IO-SRB 和 CO-SRB 与产甲烷菌具有独特的微生物相互作用，IO-SRB 与乙酰营养产甲烷菌之间存在潜在的共养关系，而 CO-SRB 与乙酰营养产甲烷菌之间存在竞争关系。