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Updated: Jun 6, 2025

Development of Sulfidogenic Sludge from Marine Sediments and Trichloroethylene Reduction in an Upflow Anaerobic Sludge Blanket Reactor
Published on: October 15, 2015
Strategies for enriching targeted sulfate-reducing bacteria and revealing their microbial interactions in anaerobic
Wenhui Shu1, Bang Du1, Guangxue Wu1
1Civil Engineering, School of Engineering, College of Science and Engineering, University of Galway, Galway H91 TK33, Ireland.
Abstract:
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.
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