Deciphering quorum sensing and quorum quenching regulatory mechanisms in anaerobic digesters: Signaling networks, environmental responses, and microbial ecological functions

Microbially driven anaerobic digestion (AD) is a key technology for energy recovery from biowaste. As critical regulators of microbial communication, quorum sensing (QS) and quorum quenching (QQ) impact AD by shaping microbial community structure and coordinating trophic-level metabolic interactions. However, their underlying mechanisms remain a “black box”, posing a significant barrier to process optimization and engineered control. This review deciphers the QS and QQ regulatory mechanisms in AD, focusing on signaling networks, environmental responsiveness, and microbial ecological functions. As current studies on QS/QQ in full-scale AD remain scarce, this review primarily draws on data from laboratory-scale reactors. First, we systematically mapped signaling molecule distribution in both liquid and solid phases across 21 anaerobic digesters, revealing that solid-phase matrices generally served as hotspots for acyl-homoserine lactone accumulation. Subsequently, the molecular mechanisms underpinning the transduction cascades of QS and QQ were dissected, including signal recognition, transmission, and interception. Furthermore, the dynamic responses of QS to environmental factors were comprehensively evaluated, together with their strong associations with microbial ecological functions and process stability. The regulatory roles of QS/QQ in extracellular polymeric substances synthesis, microbial spatial organization, metabolic pathway optimization, system robustness, and antibiotic resistance gene dissemination were also reviewed. Finally, challenges and prospects were discussed, including elucidating diverse signaling molecules roles, mapping QS/QQ signaling to metabolic pathways, and assessing long-term stability and ecological risks of QS/QQ strategies in engineering. This review offers a strategic reference for precisely regulating microbial metabolic networks and mitigating ecological risks in anaerobic digesters via signal transduction.