title: Identification and occurrence of tetrad-forming Alphaproteobacteria in anaerobic-aerobic activated sludge processes.
abstract: In an acetate-fed anaerobic-aerobic membrane bioreactor, a deteriorated enhanced biological phosphorus removal (EBPR) community was developed (as determined based on the chemical profiles of organic substrate, soluble phosphate, and intracellular carbohydrate and polyhydroxyalkanote (PHA) concentrations). Microscopic observations revealed the dominance of tetrad-forming organisms (TFOs), of which the majority stained positively for PHA under anaerobic conditions. Fluorescence in situ hybridization (FISH) confirmed that the Alphaproteobacteria (85.0+/-7.0% of total cells) were the most dominant group. A 16S rRNA gene clone library specific for the Alphaproteobacteria indicated that most 16S rRNA gene clones (61% of total clones) were closely affiliated with 'Defluvicoccus vanus', forming a cluster within subgroup 1 of the Alphaproteobacteria. Combined PHA staining and FISH with specific probes designed for the members of the 'Defluvicoccus' cluster suggested diversity within this TFO cluster, and that these TFOs were newly identified glycogen-accumulating organisms in EBPR systems. However, these 'Defluvicoccus'-related TFOs were only seen in low abundance in 12 different EBPR and non-EBPR systems, suggesting that they were not the key populations responsible for the deterioration of full-scale EBPR processes.
authors.affiliation: Environmental Science and Engineering Program and Department of Civil Engineering, National University of Singapore, Singapore 117576.
authors.forename: Man-Tak
authors.initials: MT
authors.lastname: Wong
authors.affiliation: Environmental Science and Engineering Program and Department of Civil Engineering, National University of Singapore, Singapore 117576.
authors.forename: Fea Mein
authors.initials: FM
authors.lastname: Tan
authors.affiliation: Environmental Science and Engineering Program and Department of Civil Engineering, National University of Singapore, Singapore 117576.
authors.forename: Wun Jern
authors.initials: WJ
authors.lastname: Ng
authors.affiliation: Environmental Science and Engineering Program and Department of Civil Engineering, National University of Singapore, Singapore 117576.
authors.forename: Wen-Tso
authors.initials: WT
authors.lastname: Liu
mesh_terms: D000332:Aerobiosis; D020561:Alphaproteobacteria / Q000145:classification* / Q000166:cytology / Q000235:genetics / Q000302:isolation & purification*; D000693:Anaerobiosis; D019149:Bioreactors; D002241:Carbohydrates / Q000032:analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000302:isolation & purification; D004275:DNA, Ribosomal / Q000737:chemistry / Q000302:isolation & purification; D020459:Genes, rRNA; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D010710:Phosphates / Q000032:analysis; D010802:Phylogeny; D011108:Polymers / Q000032:analysis; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012244:Rhodospirillaceae / Q000235:genetics; D017422:Sequence Analysis, DNA; D012722:Sewage / Q000382:microbiology*; D014871:Water Microbiology
chemical_list: D002241:Carbohydrates; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D010710:Phosphates; D011108:Polymers; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012722:Sewage