title: The potential role of 'Candidatus Microthrix parvicella' in phosphorus removal during sludge bulking in two full-scale enhanced biological phosphorus removal plants.
abstract: We investigated the bacterial community compositions and phosphorus removal performance under sludge bulking and non-bulking conditions in two biological wastewater treatment systems (conventional A²/O (anaerobic/anoxic/aerobic) and inverted A²/O (anoxic/anaerobic/aerobic) processes) receiving the same raw wastewater. Sludge bulking resulted in significant shift in bacterial compositions from Proteobacteria dominance to Actinobacteria dominance, characterized by the significant presence of filamentous 'Candidatus Microthrix parvicella'. Quantitative real-time polymerase chain reaction (PCR) analysis revealed that the relative abundance of 'Candidatus Accumulibacter phosphatis', a key polyphosphate-accumulating organism responsible for phosphorus removal, with respect to 16s rRNA genes of total bacteria was 0.8 and 0.7%, respectively, for the conventional and inverted A²/O systems when sludge bulking occurred, which increased to 8.2 and 12.3% during the non-bulking period. However, the total phosphorus removal performance during the bulking period (2-week average: 97 ± 1 and 96 ± 1%, respectively) was not adversely affected comparable to that during the non-bulking period (2-week average: 96 ± 1 and 96 ± 1%, respectively). Neisser staining revealed the presence of large polyphosphate granules in 'Candidatus Microthrix parvicella', suggesting that this microbial group might have been responsible for phosphorus removal during the sludge bulking period when 'Candidatus Accumulibacter phosphatis' was excluded from the systems.
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China E-mail: yangmin@rcees.ac.cn.
authors: Juan
authors: J
authors: Wang
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China E-mail: yangmin@rcees.ac.cn.
authors: Rong
authors: R
authors: Qi
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China E-mail: yangmin@rcees.ac.cn.
authors: Miaomiao
authors: M
authors: Liu
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China E-mail: yangmin@rcees.ac.cn; College of Geosciences, China University of Petroleum, Beijing 100044, China.
authors: Qian
authors: Q
authors: Li
authors: Beijing Drainage Group Co., Ltd, Beijing 100044, China.
authors: Haipeng
authors: H
authors: Bao
authors: Beijing Drainage Group Co., Ltd, Beijing 100044, China.
authors: Yaming
authors: Y
authors: Li
authors: Beijing Drainage Group Co., Ltd, Beijing 100044, China.
authors: Shen
authors: S
authors: Wang
authors: Water Research Institute, CNR, via Salaria km 29.300, 00015 Monterotondo (RM), Italy.
authors: Valter
authors: V
authors: Tandoi
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, P.O. Box 2871, Beijing 100085, China E-mail: yangmin@rcees.ac.cn.
authors: Min
authors: M
authors: Yang
mesh_terms: D019149:Bioreactors; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000145:classification / Q000235:genetics; D010758:Phosphorus / Q000378:metabolism*; D010802:Phylogeny; D020560:Proteobacteria / Q000145:classification / Q000502:physiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012722:Sewage / Q000737:chemistry*; D064091:Waste Disposal Facilities
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D010758:Phosphorus