Putative glycogen-accumulating organisms belonging to the Alphaproteobacteria identified through rRNA-based stable isotope probing

  • Rikke Louise Meyer
    Advanced Wastewater Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia
  • Aaron Marc Saunders
    Advanced Wastewater Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia
  • Linda Louise Blackall
    Advanced Wastewater Management Centre, The University of Queensland, St Lucia, QLD 4072, Australia

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<jats:p>Deterioration of enhanced biological phosphorus removal (EBPR) has been linked to the proliferation of glycogen-accumulating organisms (GAOs), but few organisms possessing the GAO metabolic phenotype have been identified. An unidentified GAO was highly enriched in a laboratory-scale bioreactor and attempts to identify this organism using conventional 16S rRNA gene cloning had failed. Therefore, rRNA-based stable isotope probing followed by full-cycle rRNA analysis was used to specifically identify the putative GAOs based on their characteristic metabolic phenotype. The study obtained sequences from a group of <jats:italic>Alphaproteobacteria</jats:italic> not previously shown to possess the GAO phenotype, but 90 % identical by 16S rRNA gene analysis to a phylogenetic clade containing cloned sequences from putative GAOs and the isolate <jats:italic>Defluvicoccus vanus</jats:italic>. Fluorescence <jats:italic>in situ</jats:italic> hybridization (FISH) probes (DF988 and DF1020) were designed to target the new group and post-FISH chemical staining demonstrated anaerobic–aerobic cycling of polyhydroxyalkanoates, as per the GAO phenotype. The successful use of probes DF988 and DF1020 required the use of unlabelled helper probes which increased probe signal intensity up to 6·6-fold, thus highlighting the utility of helper probes in FISH. The new group constituted 33 % of all <jats:italic>Bacteria</jats:italic> in the lab-scale bioreactor from which they were identified and were also abundant (51 and 55 % of <jats:italic>Bacteria</jats:italic>) in two other similar bioreactors in which phosphorus removal had deteriorated. Unlike the previously identified <jats:italic>Defluvicoccus</jats:italic>-related organisms, the group identified in this study were also found in two full-scale treatment plants performing EBPR, suggesting that this group may be industrially relevant.</jats:p>

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  • Microbiology

    Microbiology 152 (2), 419-429, 2006-02-01

    Microbiology Society

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