Detailed comparison of bacterial communities during seasonal sludge bulking in a municipal wastewater treatment plant.
In this study, pyrosequencing combined with clone library analysis, qPCR, and fluorescent in situ hybridization (FISH) were performed to identify detailed changes of bacterial and filamentous bacterial communities in activated sludge (AS) in 3 types of typical AS samples: sludge bulking (B-AS), excessive bulking (EB-AS), and non-bulking (N-AS). Sludge bulking resulted in a decrease in total bacterial numbers from (6.4 ± 0.18) × 108gene copies/mL in N-AS to (2.4 ± 0.22) × 108in EB-AS and a decrease in bacterial diversity from 2757 OTUs in N-AS to 2217 OTUs in EB-AS. With the occurrence of sludge bulking, Actinobacteria and Firmicutes increased sharply, whereas Proteobacteria, which was the predominant phylum in N-AS, decreased markedly. In addition, Nitrospirae, a major lineage of the nitrite-oxidizing bacteria, had quite a low abundance in EB-AS (0.15%), while it was relatively high in N-AS (1.17%). On the other hand, filamentous bacteria accounted for 28.77% and 5.72% of total sequences in EB-AS and N-AS, respectively. More interestingly, 11 types of filamentous bacteria were always present in 3 types of typical AS samples from different stages of sludge bulking, and most of them enriched in EB-AS compared to N-AS. It is noteworthy that, in addition to the frequently reported filamentous bacteria such as Candidatus M. parvicella and Tetrasphaera, novel filamentous species of Trichococcus might exist in this bulking WWTP. Our results reveal that sludge bulking are derived from diverse taxa, which expands previous understanding and provides new insight into the underlying complications of the bulking phenomenon in AS.
College of Resources and Environment, University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing 100049, PR China.
Ping
P
Wang
College of Resources and Environment, University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing 100049, PR China. Electronic address: yuzs@ucas.ac.cn.
Zhisheng
Z
Yu
Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, 18 Shuangqing Road, Beijing 100085, PR China.
Rong
R
Qi
College of Resources and Environment, University of Chinese Academy of Sciences, 19 A Yuquan Road, Beijing 100049, PR China.
Hongxun
H
Zhang
D001419:Bacteria / Q000235:genetics; D017404:In Situ Hybridization, Fluorescence; D012621:Seasons; D012722:Sewage / Q000382:microbiology*; D062065:Wastewater / Q000382:microbiology*
D012722:Sewage; D062065:Wastewater
Bacterial community; Filamentous bacteria; Sludge bulking; Wastewater treatment plant