Phylogenetic analysis of nitrate- and sulfate-reducing bacteria in a hydrogen-fed biofilm

• Published in: FEMS microbiology ecology 2013-07, Vol.85 (1), p.158-167
• Main Authors: Ontiveros-Valencia, Aura, Ilhan, Zehra Esra, Kang, Dae-Wook, Rittmann, Bruce, Krajmalnik-Brown, Rosa
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Autotrophic Processes; autotrophs; Bacteria; Bacteria - classification; Bacteria - isolation & purification; Bacteria - metabolism; Biofilms; Biological and medical sciences; Biological evolution; Bioreactors; Community structure; Denitrification; Ecology; electron acceptor; electron‐donor availability; Environmental Sciences; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Heterotrophic Processes; heterotrophs; Hydrogen - metabolism; Microbial ecology; Microbial Interactions; Microbiology; Nitrates - metabolism; Oxidation-Reduction; Phylogeny; pyrosequencing; Relative abundance; Sulfate reduction; Sulfates; Sulfates - metabolism; Various environments (extraatmospheric space, air, water)
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1111/1574-6941.12107

Abstract Using two membrane biofilm reactors in which hydrogen (H2) was the only exogenous electron donor, we studied the microbial community structure of biofilms composed primarily of denitrifying bacteria (DB) and sulfate-reducing bacteria (SRB). In steady-state EDvSS, H2 availability was restricted and varied. In steady-state EAvSS, the input nitrate (NO3−) concentration was varied relative to a fixed sulfate (SO42−) concentration. SRB co-existed with DB, even when SO42− reduction was absent due to restricted H2 availability. UniFrac and principal coordinate analysis indicated that H2 availability and electron-acceptor loadings framed the microbial community structure, with H2 availability having a greater impact. In EDvSS, restricted H2 availability favored heterotrophic DB (i.e. Burkholderiales) compared with autotrophic DB (e.g. Hydrogenophilales and Rhodocyclales). In EAvSS, SO42− reduction lowered the relative abundance of some DB (e.g. Hydrogenophilales), and the biofilm was colonized by Desulfovibrionales and Bacteroidales. Reinforcing the impact of H2 availability, EAvSS showed a higher microbial diversity and more even distribution among microbial groups than did EDvSS. Thus, the biofilm community in a H2-fed biofilm with DB and SRB became more heterotrophic when the H2 availability was constrained, while low NO3− loading allowed more SO42− reduction, causing a shift to more SRB.