title: Accumulibacter clades Type I and II performing kinetically different glycogen-accumulating organisms metabolisms for anaerobic substrate uptake.
abstract: The anaerobic acetate (HAc) uptake stoichiometry of phosphorus-accumulating organisms (PAO) in enhanced biological phosphorus removal (EBPR) systems has been an extensive subject of study due to the highly variable reported stoichiometric values (e.g. anaerobic P-release/HAc-uptake ratios ranging from 0.01 up to 0.93 P-mol/C-mol). Often, such differences have been explained by the different applied operating conditions (e.g. pH) or occurrence of glycogen-accumulating organisms (GAO). The present study investigated the ability of biomass highly enriched with specific PAO clades ('Candidatus Accumulibacter phosphatis' Clade I and II, hereafter PAO I and PAO II) to adopt a GAO metabolism. Based on long-term experiments, when Poly-P is not stoichiometrically limiting for the anaerobic VFA uptake, PAO I performed the typical PAO metabolism (with a P/HAc ratio of 0.64 P-mol/C-mol); whereas PAO II performed a mixed PAO-GAO metabolism (showing a P/HAc ratio of 0.22 P-mol/C-mol). In short-term batch tests, both PAO I and II gradually shifted their metabolism to a GAO metabolism when the Poly-P content decreased, but the HAc-uptake rate of PAO I was 4 times lower than that of PAO II, indicating that PAO II has a strong competitive advantage over PAO I when Poly-P is stoichiometrically limiting the VFA uptake. Thus, metabolic flexibility of PAO clades as well as their intrinsic differences are additional factors leading to the controversial anaerobic stoichiometry and kinetic rates observed in previous studies. From a practical perspective, the dominant type of PAO prevailing in full-scale EBPR systems may affect the P-release processes for biological or combined biological and chemical P-removal and recovery and consequently the process performance.
authors.affiliation: Department of Environmental Engineering and Technology, UNESCO-IHE Institute for Water Education, Westvest 7, 2611AX Delft, The Netherlands; Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. Electronic address: laurenswelles@gmail.com.
authors.forename: L
authors.initials: L
authors.lastname: Welles
authors.affiliation: Southwest Municipal Engineering Design and Research Institute of China, Shennan Road East NO. 1110, Shenzhen 518000, PR China; Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. Electronic address: hittwd@gmail.com.
authors.forename: W D
authors.initials: WD
authors.lastname: Tian
authors.affiliation: Department of Environmental Engineering and Technology, UNESCO-IHE Institute for Water Education, Westvest 7, 2611AX Delft, The Netherlands; Department of Civil Engineering, Ain Shams University, 1 El Sarayat st., Abbassia, 11517 Cairo, Egypt. Electronic address: sondos.abdel-hakim@eng.asu.edu.eg.
authors.forename: S
authors.initials: S
authors.lastname: Saad
authors.affiliation: Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. Electronic address: b.a.abbas@tudelft.nl.
authors.forename: B
authors.initials: B
authors.lastname: Abbas
authors.affiliation: Department of Environmental Engineering and Technology, UNESCO-IHE Institute for Water Education, Westvest 7, 2611AX Delft, The Netherlands. Electronic address: c.lopezvazquez@unesco-ihe.org.
authors.forename: C M
authors.initials: CM
authors.lastname: Lopez-Vazquez
authors.affiliation: Department of Environmental Engineering and Technology, UNESCO-IHE Institute for Water Education, Westvest 7, 2611AX Delft, The Netherlands. Electronic address: t.hooijmans@unesco-ihe.org.
authors.forename: C M
authors.initials: CM
authors.lastname: Hooijmans
authors.affiliation: KWR Watercycle Research Institute, Groningenhaven 7, 3433 PE Nieuwegein, The Netherlands; Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. Electronic address: m.c.m.vanloosdrecht@tudelft.nl.
authors.forename: M C M
authors.initials: MC
authors.lastname: van Loosdrecht
authors.affiliation: Department of Environmental Engineering and Technology, UNESCO-IHE Institute for Water Education, Westvest 7, 2611AX Delft, The Netherlands; Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft, The Netherlands. Electronic address: d.brdjanovic@unesco-ihe.org.
authors.forename: D
authors.initials: D
authors.lastname: Brdjanovic
mesh_terms: D000085:Acetates / Q000378:metabolism; D000693:Anaerobiosis; D020562:Betaproteobacteria / Q000145:classification / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors; D005232:Fatty Acids, Volatile / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D010758:Phosphorus / Q000378:metabolism*; D011122:Polyphosphates / Q000378:metabolism; D014865:Waste Disposal, Fluid; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D000085:Acetates; D005232:Fatty Acids, Volatile; D011122:Polyphosphates; D014874:Water Pollutants, Chemical; D010758:Phosphorus; D006003:Glycogen
keywords: Enhanced biological phosphorus removal (EBPR); Glycogen-accumulating organisms (GAO); Intracellular P-content; Metabolic shift; Phosphate-accumulating organisms (PAO); ‘Candidatus Accumulibacter phosphatis’ Clade I and II