title: Anaerobic and aerobic metabolism of glycogen-accumulating organisms selected with propionate as the sole carbon source.
abstract: 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 post-fluorescence in situ hybridization (FISH) chemical staining confirmed that these Alphaproteobacteria produced poly-beta-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.
authors.affiliation: Advanced Wastewater Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane 4072, Australia.
authors.forename: Adrian
authors.initials: A
authors.lastname: Oehmen
authors.affiliation: Advanced Wastewater Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane 4072, Australia.
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Zeng
authors.affiliation: Advanced Wastewater Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane 4072, Australia.
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Saunders
authors.affiliation: Advanced Wastewater Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane 4072, Australia.
authors.forename: Linda L
authors.initials: LL
authors.lastname: Blackall
authors.affiliation: Advanced Wastewater Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane 4072, Australia.
authors.forename: Jürg
authors.initials: J
authors.lastname: Keller
authors.affiliation: Advanced Wastewater Management Centre (AWMC), The University of Queensland, St Lucia, Brisbane 4072, Australia.
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D000332:Aerobiosis / Q000502:physiology; D020561:Alphaproteobacteria / Q000378:metabolism*; D000693:Anaerobiosis / Q000502:physiology; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology; D002244:Carbon / Q000378:metabolism*; D006003:Glycogen / Q000378:metabolism*; D017404:In Situ Hybridization, Fluorescence; D011422:Propionates / Q000378:metabolism*
chemical_list: D011422:Propionates; D002244:Carbon; D006003:Glycogen