Interactions between Nitrate-Reducing and Sulfate-Reducing Bacteria Coexisting in a Hydrogen-Fed Biofilm

• Published in: Environmental science & technology Vol. 46; no. 20; pp. 11289 - 11298
• Main Authors: Ontiveros-Valencia, Aura, Ziv-El, Michal, Zhao, He-Ping, Feng, Liang, Rittmann, Bruce E, Krajmalnik-Brown, Rosa
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 16.10.2012
• Subjects: Applied sciences; Bacteria; Bacteria - metabolism; Biofilms; Biofilms - growth & development; Biological and medical sciences; Biological and physicochemical phenomena; Biological treatment of waters; Bioreactors - microbiology; Biotechnology; Denitrification; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environment and pollution; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Hydrogen - metabolism; Industrial applications and implications. Economical aspects; Membrane reactors; Microbial Interactions; Natural water pollution; Nitrates; Nitrates - analysis; Nitrates - metabolism; Phylogeny; Pollution; Pollution, environment geology; Polymerase chain reaction; Sulfates - analysis; Sulfates - metabolism; Waste Disposal, Fluid - methods; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - metabolism; Water treatment and pollution; Sulfur compounds; Sulfate-reducing bacteria; Nitrites; Nitrogen compounds; Competitive reaction; Nitrates; Sulfates; Microbial biomass; Polymerase chain reaction; Membrane reactor; Decontamination; Biofilm; Water pollution; Bioremediation
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es302370t

To explore the relationships between denitrifying bacteria (DB) and sulfate-reducing bacteria (SRB) in H2-fed biofilms, we used two H2-based membrane biofilm reactors (MBfRs) with or without restrictions on H2 availability. DB and SRB compete for H2 and space in the biofilm, and sulfate (SO4 2–) reduction should be out-competed when H2 is limiting inside the biofilm. With H2 availability restricted, nitrate (NO3 –) reduction was proportional to the H2 pressure and was complete at a H2 pressure of 3 atm; SO4 2– reduction began at H2 ≥ 3.4 atm. Without restriction on H2 availability, NO3 – was the preferred electron acceptor, and SO4 2– was reduced only when the NO3 – surface loading was ≤0.13 g N/m2-day. We assayed DB and SRB by quantitative polymerase chain reaction targeting the nitrite reductases and dissimilatory sulfite reductase, respectively. Whereas DB and SRB increased with higher H2 pressures when H2 availability was limiting, SRB did not decline with higher NO3 – removal flux when H2 availability was not limiting, even when SO4 2– reduction was absent. The SRB trend reflects that the SRB’s metabolic diversity allowed them to remain in the biofilm whether or not they were reducing SO4 2–. In all scenarios tested, the SRB were able to initiate strong SO4 2– reduction only when competition for H2 inside the biofilm was relieved by nearly complete removal of NO3 –.