A review of quorum sensing regulating heavy metal resistance in anammox process: Relations, mechanisms and prospects

Quorum sensing (QS) is a crucial process of intercellular communication in bacteria that synchronizes their gene expression and physiological behaviors. This ability assists bacteria in surviving under environmental stressors. One such prevalent environmental stressor is heavy metals, which can significantly impair bacterial function, with anaerobic ammonium oxidation (anammox) consortia being particularly susceptible. Herein, we systematically and critically review the key information about QS regulation to enhance heavy metal resistance of anammox consortia. This review first discusses the interaction between QS and heavy metal, then elaborates on QS regulations for anammox consortia behaviors, revealing the ternary relations among QS, heavy metal and anammox. Furthermore, the underlying mechanisms of QS regulation to heavy metal resistance in anammox consortia are analyzed, including how QS regulates extracellular polymeric substances biosorption, antioxidant defense, electron transfer, resistance to bacterial infection and microbial interaction. This work deepens the understanding of the QS regulatory mechanisms that enable bacterial survival in response to environmental stressors, providing a fundamental basis for applying QS regulation to enhance bacterial resistance in the environmental engineering.