The large PAO cells in full-scale EBPR biomass samples are not yeast spores but possibly novel members of the beta-Proteobacteria

Large, homogenous clusters of coccobacilli were found to be abundant in the biomasses from a conventional plant at Rosebud, Victoria, Australia. The identity and the in situ physiology of these dominant microorganisms were investigated in this study. These large clustered cells were revealed to be n...

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Bibliographic Details
Published in:Water science and technology 2004-01, Vol.50 (6), p.123-130
Main Authors: Chua, A S M, Eales, K, Mino, T, Seviour, R
Format: Article
Language:English
Subjects:
Anaerobic conditions
Assimilation
Australia
Autoradiography
Bacteria
Betaproteobacteria - isolation & purification
Betaproteobacteria - metabolism
Bioaccumulation
Biodiversity
Biomass
Bioreactors
Fluorescence
Gram-negative bacteria
Granular materials
In Situ Hybridization
Microorganisms
Organic Chemicals - metabolism
Phosphates
Phosphorus removal
Physiology
Polyhydroxyalkanoates
Probes
Sewage - microbiology
Spores
Spores, Fungal - isolation & purification
Spores, Fungal - metabolism
Staining
Substrates
Waste Disposal, Fluid - methods
Yeast
Yeasts
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Summary:Large, homogenous clusters of coccobacilli were found to be abundant in the biomasses from a conventional plant at Rosebud, Victoria, Australia. The identity and the in situ physiology of these dominant microorganisms were investigated in this study. These large clustered cells were revealed to be neither Gram positive nor Gram negative bacteria and contain polyP granules. Cells with similar features were also observed in some enhanced biological phosphate removal (EBPR) systems and reported as yeast spores and Rhodocyclus-related polyphosphate accumulating organisms (PAOs). In this study, fluorescent in situ hybridization (FISH) probing showed these cells were prokaryotic and members of the beta-Proteobacteria. However, these large clustered cells did not respond to the PAO mix FISH probes. The in situ physiology of these large cells was studied with FISH in combination with microautoradiography (MAR) in order to understand their substrate assimilation abilities under different conditions as well as their phosphate uptake ability. These cells were able to take up acetate, glutamate and aspartate, but not glucose under both aerobic and anaerobic conditions. Nile Blue A staining in combination with MAR showed that cells incubated under anaerobic conditions contained polyhydroxyalkanoates (PHA) granules. In addition, MAR showed aerobic 33Pi assimilation with all these substrates, consistent with them supporting an EBPR capacity in these large cells. As well as raising doubts about a role for yeasts in EBPR, this study suggests that much still needs to be learned about the identity and level of biodiversity of the PAO in EBPR systems, and emphasizes the benefits of using techniques like FISH/MAR and PHA staining/MAR to resolve the in situ physiology of the populations of interest there.
ISSN:0273-1223
1996-9732
DOI:10.2166/wst.2004.0368