城市污水处理厂Candidatus Accumulibacter的菌群结构及定量分析

Candidatus Accumulibacter是污水生物除磷系统中的优势聚磷菌.本研究采用编码聚合磷酸盐激酶的功能基因(polyphosphate kinase 1gene,ppk1)作为遗传标记,对9个污水处理厂共12个活性污泥样品中Accumulibacter的进化枝水平的丰度及其菌群结构进行了研究.实时定量PCR(Quantitative PCR,QPCR)的结果显示,Accumulibacter的6个进化枝(IA、IIA、IIB、IIC、IID、IIF)均存在于12个污泥样品中.A2O及其改良工艺中总Accumulibacter丰度最高,达到总菌的22.77%.所有样品中Accumulibacter均以Type-II为主,其中,IIC、IID的丰度均达到了108cells·g-1(以MLSS计),占Accumulibacter的平均比例分别为75.34%和14.87%,是污水处理厂中的优势聚磷菌.分支IA丰度最低,占总Accumulibacter比例平均只有0.32%.系统发育分析结果显示,每个样品中Accumulibacter分支多样化,均含有IIA、IIC、IID分支.QPCR和系统发育分析都证实了生物除磷效果与Accumulibacter的群落结构密切相关,除磷效果不好可能和IID占总Accumulibacter比例较高有关.

Community structures and quantitative analyses of Candidatus Accumulibacter in municipal wastewater treatment plants

Candidatus Accumulibacter has been identified as dominant polyphosphate-accumulating organisms (PAOs) in enhanced biological phosphorus (P) removal (EBPR) sludges. This study investigated the clade-level community structures and population dynamics of Accumulibacter using polyphosphate kinase 1 gene (ppk1) genes in 12 sludge samples from nine full-scale wastewater treatment plants (WWTPs). Results of Quantitative PCR indicate that six clades (IA, IIA, IIB, IIC, IID and IIF) of Accumulibacter were found in the 12 sludge samples. Abundances of Accumulibacter in the anaerobic-anoxic-oxic (A²O) and improved processes were the highest, up to 22.77% of total bacteria. Abundance of IIC and IID reached 10⁸ cells·g^-1 MLSS, accounting for 75.34% and 14.87% of total Accumulibacter, respectively. They were the dominant species of Accumulibacter. Clade IA abundance was the lowest, with an average 0.32% of total Accumulibacter. Clades IIA, IIC and IID were found in all sludge samples, indicating the clades diversity in the sludge samples. Quantitative PCR and phylogenetic analysis confirmed EBPR performance was closely related to the clade-level community structures of Accumulibacter. Poor EBPR performance was possibly related to a high proportion of IID to total Accumulibacter.