Bacterial signaling and signal responses as key factors in water and wastewater treatment

Quorum sensing (QS), a means of communication between microorganisms that controls group behaviors, has been intensively studied for the past 50 years in the medical, agricultural, and environmental fields. However, despite considerable efforts in understanding the molecular mechanisms and implications of QS in pure culture systems, the role of QS in complex microbial communities remains largely understudied. Several studies have recently demonstrated that controlling the QS system can enhance the performance of various wastewater treatment systems, particularly in membrane-based water purification systems. Further, these studies demonstrated that QS and quorum quenching (QQ) have several vital roles in wastewater treatment systems; however, the mechanisms by which these factors regulate complex systems are not well understood. This review provides an overview of the roles of bacterial signaling and signal responses in a variety of wastewater treatment systems including granular sludge systems, membrane filtration, pollutant biodegradation, bioaugmentation, and bio-electricity generation.