title: Anaerobic metabolism of propionate by polyphosphate-accumulating organisms in enhanced biological phosphorus removal systems.
abstract: Propionate, a carbon substrate abundant in many prefermenters, has been shown in several previous studies to be a more favorable substrate than acetate for enhanced biological phosphorus removal (EBPR). The anaerobic metabolism of propionate by polyphosphate accumulating organisms (PAOs) is studied in this paper. A metabolic model is proposed to characterize the anaerobic biochemical transformations of propionate uptake by PAOs. The model is demonstrated to predict very well the experimental data from a PAO culture enriched in a laboratory-scale reactor with propionate as the sole carbon source. Quantitative fluorescence in-situ hybridization (FISH) analysis shows that Candidatus Accumulibacter phosphatis, the only identified PAO to date, constitute 63% of the bacterial population in this culture. Unlike the anaerobic metabolism of acetate by PAOs, which induces mainly poly-beta-hydroxybutyrate (PHB) production, the major fractions of poly-beta-hydroxyalkanoate (PHA) produced with propionate as the carbon source are poly-beta-hydroxyvalerate (PHV) and poly-beta-hydroxy-2-methylvalerate (PH2MV). PHA formation correlates very well with a selective (or nonrandom) condensation of acetyl-CoA and propionyl-CoA molecules. The maximum specific propionate uptake rate by PAOs found in this study is 0.18 C-mol/C-mol-biomass . h, which is very similar to the maximum specific acetate uptake rate reported in literature. The energy required for transporting 1 carbon-mole of propionate across the PAO cell membrane is also determined to be similar to the transportation of 1 carbon-mole of acetate. Furthermore, the experimental results suggest that PAOs possess a similar preference toward acetate and propionate uptake on a carbon-mole basis.
authors.affiliation: Advanced Wastewater Management Centre, The University of Queensland, St. Lucia, Brisbane 4072, Australia.
authors.forename: Adrian
authors.initials: A
authors.lastname: Oehmen
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Zeng
authors.forename: Zhiguo
authors.initials: Z
authors.lastname: Yuan
authors.forename: Jürg
authors.initials: J
authors.lastname: Keller
mesh_terms: D001421:Bacteria, Anaerobic / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods; D003198:Computer Simulation; D008954:Models, Biological; D010758:Phosphorus / Q000493:pharmacokinetics*; D010865:Pilot Projects; D011122:Polyphosphates / Q000378:metabolism*; D011422:Propionates / Q000493:pharmacokinetics*; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics; D018508:Water Purification / Q000379:methods*
chemical_list: D011122:Polyphosphates; D011422:Propionates; D014874:Water Pollutants, Chemical; D010758:Phosphorus