Identification and occurrence of tetrad-forming Alphaproteobacteria in anaerobic–aerobic activated sludge processes

Wong, Man Tak; Tan, Fea Mein; Ng, Wun Jern; Liu, Wen Tso

doi:10.1099/mic.0.27291-0

Cited by 179 publications

(199 citation statements)

References 42 publications

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“…DF2MIX (Table 1) Defluvicoccus-related organisms accounted for an additional 8 % (SEM=1 %) of the Bacteria, and the cells that bound these probes were TFOs. The fact that the majority of Alphaproteobacteria in the biomass that cycled PHA did not bind the current probes for GAOs strongly suggests the presence of other GAOs, despite the similar morphology of these organisms to those described in the literature (Beer et al, 2004;Meyer et al, 2006;Wong et al, 2004). It may be that the probes from these publications do not target the diversity of the organisms within these already identified groups so that additional sequences are required in order to broaden the probe specificities; alternatively, another group of GAOs unrelated to Sphingomonas or D. vanus may exist.…”

Section: Fish and Post-fish Chemical Stainingmentioning

confidence: 90%

“…One group are members of the order Sphingomonadales, and the other is related to the isolate Defluvicoccus vanus within the order Rhodospirillales. Both of these organisms could consume acetate as the sole carbon source (Beer et al, 2004;Wong et al, 2004), but the D. vanus-related organism has also been recently demonstrated to consume propionate (Meyer et al, 2006), unlike Competibacter.…”

Section: Introductionmentioning

confidence: 99%

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Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source

et al. 2006

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In the microbial competition observed in enhanced biological phosphorus removal (EBPR) systems, an undesirable group of micro-organisms known as glycogen-accumulating organisms (GAOs) compete for carbon in the anaerobic period with the desired polyphosphate-accumulating organisms (PAOs). Some studies have suggested that a propionate carbon source provides PAOs with a competitive advantage over GAOs in EBPR systems; however, the metabolism of GAOs with this carbon source has not been previously investigated. In this study, GAOs were enriched in a laboratory-scale bioreactor with propionate as the sole carbon source, in an effort to better understand their biochemical processes. Based on comprehensive solid-, liquid-and gas-phase chemical analytical data from the bioreactor, a metabolic model was proposed for the metabolism of propionate by GAOs. The model adequately described the anaerobic stoichiometry observed through chemical analysis, and can be a valuable tool for further investigation of the competition between PAOs and GAOs, and for the optimization of the EBPR process. A group of Alphaproteobacteria dominated the biomass (96 % of Bacteria) from this bioreactor, while postfluorescence in situ hybridization (FISH) chemical staining confirmed that these Alphaproteobacteria produced poly-b-hydroxyalkanoates (PHAs) anaerobically and utilized them aerobically, demonstrating that they were putative GAOs. Some of the Alphaproteobacteria were related to Defluvicoccus vanus (16 % of Bacteria), but the specific identity of many could not be determined by FISH. Further investigation into the identity of other GAOs is necessary.

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Section: Fish and Post-fish Chemical Stainingmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source

et al. 2006

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“…Cluster 1 Defluviicoccus always constituted <1 % of Bacteria in plants surveyed here. Previous surveys of full-scale plants from several countries (Wong et al, 2004(Wong et al, , 2005) also demonstrated low numbers of Cluster Not included 2 h anaerobic 2 1C. Anaerobic 3 h anaerobic; 1.5 mM unlabelled acetate added at t=0 2 h anaerobic +/2 1D.…”

Section: Resultsmentioning

confidence: 99%

“…FISH probes used in this study were NON338 for non-specific binding (Wallner et al, 1993), EUBMIX for Bacteria (Amann et al, 1990;Daims et al, 1999), DF1MIX (TFO_DF218 plus TFO_DF618) for the Alphaproteobacteria from Cluster 1 Defluviicoccus spp. (Wong et al, 2004), DF2MIX (DF988, DF1020 plus helper probes H966 and H1038) for Cluster 2 Defluviicoccus spp. (Meyer et al, 2006), SBR9-1a for Alphaproteobacteria Sphingomonas spp.…”

Section: Methodsmentioning

confidence: 99%

“…However, some lab-scale investigations have suggested that uncultured organisms belonging to the Alphaproteobacteria also play a role in breakdown of stable EBPR. These organisms have been phylogenetically identified as closely related to the pure culture Defluviicoccus vanus (Meyer et al, 2006;Wong et al, 2004) and Sphingomonas spp. (Beer et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

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Abundance and ecophysiology of Defluviicoccus spp., glycogen-accumulating organisms in full-scale wastewater treatment processes

et al. 2007

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The activity of glycogen-accumulating organisms (GAOs) in enhanced biological phosphorus removal (EBPR) wastewater treatment plants has been proposed as one cause of deterioration of EBPR. Putative GAOs from the Alphaproteobacteria, Defluviicoccus spp. (including D. vanus), were studied in full-scale EBPR plants to determine their distribution, abundance and ecophysiology. Fluorescence in situ hybridization (FISH) demonstrated that Defluviicoccus spp. were generally low in abundance; however, in one plant surveyed, Cluster 2 Defluviicoccus constituted 9 % of all Bacteria. FISH combined with microautoradiography revealed that both Cluster 1 and Cluster 2 Defluviicoccus were capable of taking up a narrow range of substrates including acetate, propionate, pyruvate and glucose under anaerobic and aerobic conditions. Formate, butyrate, ethanol and several other substrates were not taken up. Cluster 2 Defluviicoccus demonstrated a phenotype consistent with the current metabolic model for GAOs -anaerobic assimilation of acetate and reduction to polyhydroxyalkanoates (PHA) using the glycolytic pathway, and aerobic consumption of PHA. Polyphosphate-accumulating organisms (PAOs, 'Candidatus Accumulibacter phosphatis') and other putative GAOs ('Candidatus Competibacter phosphatis') co-existed in two plants with Cluster 2 Defluviicoccus, but in both plants, the latter organisms were more abundant. Thus Cluster 2 Defluviicoccus can be relatively abundant and could be carbon competitors of PAOs and other GAOs in EBPR plants.

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Comparison of acetate and propionate uptake by polyphosphate accumulating organisms and glycogen accumulating organisms

Oehmen

Yuan

Blackall

et al. 2005

Biotech & Bioengineering

245

130

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Enhanced biological phosphorus removal (EBPR) performance is directly affected by the competition between polyphosphate accumulating organisms (PAOs) and glycogen accumulating organisms (GAOs). This study investigates the effects of carbon source on PAO and GAO metabolism. Enriched PAO and GAO cultures were tested with the two most commonly found volatile fatty acids (VFAs) in wastewater systems, acetate and propionate. Four sequencing batch reactors (SBRs) were operated under similar conditions and influent compositions with either acetate or propionate as the sole carbon source. The stimulus for selection of the PAO and GAO phenotypes was provided only through variation of the phosphorus concentration in the feed. The abundance of PAOs and GAOs was quantified using fluorescence in situ hybridisation (FISH). In the acetate fed PAO and GAO reactors, "Candidatus Accumulibacter phosphatis" (a known PAO) and "Candidatus Competibacter phosphatis" (a known GAO) were present in abundance. A novel GAO, likely belonging to the group of Alphaproteobacteria, was found to dominate the propionate fed GAO reactor. The results clearly show that there are some very distinctive differences between PAOs and GAOs in their ability to take up acetate and propionate. PAOs enriched with acetate as the sole carbon source were immediately able to take up propionate, likely at a similar rate as acetate. However, an enrichment of GAOs with acetate as the sole carbon source took up propionate at a much slower rate (only about 5% of the rate of acetate uptake on a COD basis) during a short-term switch in carbon source. A GAO enrichment with propionate as the sole carbon source took up acetate at a rate that was less than half of the propionate uptake rate on a COD basis. These results, along with literature reports showing that PAOs fed with propionate (also dominated by Accumulibacter) can immediately switch to acetate, suggesting that PAOs are more adaptable to changes in carbon source as compared to GAOs. This study suggests that the PAO and GAO competition could be influenced in favour of PAOs through the provision of propionate in the feed or even by regularly switching the dominant VFA species in the wastewater. Further study is necessary in order to provide greater support for these hypotheses.

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Identification and occurrence of tetrad-forming Alphaproteobacteria in anaerobic–aerobic activated sludge processes

Cited by 179 publications

References 42 publications

Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source

Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source

Abundance and ecophysiology of Defluviicoccus spp., glycogen-accumulating organisms in full-scale wastewater treatment processes

Comparison of acetate and propionate uptake by polyphosphate accumulating organisms and glycogen accumulating organisms

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