The role of bacterial communication in activated sludge at low temperatures

Highlights•Quorum-sensing bacteria act as pioneers during activated sludge biofilm colonization•Quorum-sensing behaviors are studied at 15°C•Enhanced biofilm formation is observed with increase of quorum-sensing gene expression•Quorum-sensing bacteria exhibit a temperature-dependent distribution patternSummaryQuorum sensing is widespread in the microbial world; however, the role of this population behavior at low temperatures (<15°C) remains poorly understood. Here, the effects of quorum sensing in wastewater treatment processes at low temperatures are revealed using both microcosm experiments and global surveys. Quorum-sensing bacteria act as pioneers to facilitate microorganism migration from the species pool to the carrier surface during biofilm colonization at 15°C. A high biofilm formation rate is accompanied by significant enrichment of quorum-sensing bacteria and upregulation of gene expression. By analyzing the global activated sludge microbiome data, we find that quorum-sensing bacteria exhibit a typical temperature-dependent distribution pattern. The performance of the process is strongly linked to the content of quorum-sensing bacteria. Our findings elucidate a potential response mechanism of the microbial community to environmental stress and provide implications for the enhancement of the wastewater biotreatment process at low temperatures.