Microbial Community Composition and Ultrastructure of Granules from a Full-Scale Anammox Reactor

Graciela Gonzalez-Gil, Rachid Sougrat, Ali Reza Behzad, Piet Nl L Lens, Pascal Saikaly

Research output: Contribution to journalArticlepeer-review

69 Scopus citations

Abstract

Granules in anammox reactors contain besides anammox bacteria other microbial communities whose identity and relationship with the anammox bacteria are not well understood. High calcium concentrations are often supplied to anammox reactors to obtain sufficient bacterial aggregation and biomass retention. The aim of this study was to provide the first characterization of bacterial and archaeal communities in anammox granules from a full-scale anammox reactor and to explore on the possible role of calcium in such aggregates. High magnification imaging using backscattered electrons revealed that anammox bacteria may be embedded in calcium phosphate precipitates. Pyrosequencing of 16S rRNA gene fragments showed, besides anammox bacteria (Brocadiacea, 32 %), substantial numbers of heterotrophic bacteria Ignavibacteriacea (18 %) and Anaerolinea (7 %) along with heterotrophic denitrifiers Rhodocyclacea (9 %), Comamonadacea (3 %), and Shewanellacea (3 %) in the granules. It is hypothesized that these bacteria may form a network in which heterotrophic denitrifiers cooperate to achieve a well-functioning denitrification system as they can utilize the nitrate intrinsically produced by the anammox reaction. This network may provide a niche for the proliferation of archaea. Hydrogenotrophic methananogens, which scavenge the key fermentation product H2, were the most abundant archaea detected. Cells resembling the polygon-shaped denitrifying methanotroph Candidatus Methylomirabilis oxyfera were observed by electron microscopy. It is hypothesized that the anammox process in a full-scale reactor triggers various reactions overall leading to efficient denitrification and a sink of carbon as biomass in anammox granules.
Original languageEnglish (US)
Pages (from-to)118-131
Number of pages14
JournalMicrobial Ecology
Volume70
Issue number1
DOIs
StatePublished - Dec 11 2014

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01

ASJC Scopus subject areas

  • Ecology
  • Ecology, Evolution, Behavior and Systematics
  • Soil Science

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