Quorum sensing bacteria improve microbial networks stability and complexity in wastewater treatment plants

Abstract

Abstract Background Quorum-sensing bacteria (QSB) are crucial for microbial communication, yet their ecological role in wastewater treatment plants (WWTPs) remains unclear. In this study, targeting 130 WWTPs across China, we aimed to construct an identification method for QSB and to explore the abundance distribution of QSB in activated sludge communities and its role in community structure. Results We developed a method to identify QSB by comparing 16S rRNA gene sequences. QSB in 388 activated sludge samples collected from 130 WWTPs across China were primarily identified as rare taxa and conditionally rare taxa. A co-occurrence network shared by all sludge communities revealed that QSB exhibited a higher average clustering coefficient (0.46) than non-QSB (0.15). Individual sludge networks demonstrated that quorum sensing microbiomes positively correlated with network robustness and complexity, including average clustering coefficient and link density. Compared with the abundance and richness of QSB, the number of quorum sensing keystones was especially critical for network robustness and connectivity. Additionally, average connectivity, average clustering coefficient and relative modularity strongly correlated with network robustness (r = 0.70–0.90), indicating the positive relationship between network complexity and stability. Hence, QSB contribute to maintaining the community stability of activated sludge. Conclusions We elucidated the ecological significance of QSB and provide guidance for improving the community structure in an artificial ecosystem.