RT Journal Article SR Electronic(1) A1 Wong, Man-Tak A1 Tan, Fea Mein A1 Ng, Wun Jern A1 Liu, Wen-TsoYR 2004 T1 Identification and occurrence of tetrad-forming Alphaproteobacteria in anaerobic–aerobic activated sludge processes JF Microbiology, VO 150 IS 11 SP 3741 OP 3748 DO https://doi.org/10.1099/mic.0.27291-0 PB Microbiology Society, SN 1465-2080, AB 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., UL https://www.microbiologyresearch.org/content/journal/micro/10.1099/mic.0.27291-0