Quorum sensing-mediated odor regulation in livestock and poultry manure: an emerging perspective

Intensive livestock and poultry production has made odor emissions a major environmental challenge. These odors arise mainly from the anaerobic microbial transformation of manure into ammonia (NH₃), hydrogen sulfide (H₂S), volatile fatty acids (VFAs), and indolic compounds. Microbial odor-control strategies include source control through dietary optimization to regulate gut microbiota and reduce odor formation, process control through microbial additives intended to suppress odor-producing microorganisms and anaerobic fermentation, and end-of-pipe treatment using biofilters or biotrickling systems to oxidize and decompose odorants. Although biological deodorization is attractive because of its environmental compatibility, cost-effectiveness, and high removal efficiency, approaches relying on single strains are often constrained by microbial competition, long start-up periods, and performance deterioration under fluctuating conditions, resulting in incomplete removal of mixed odors. Quorum sensing (QS), as a community-level microbial communication mechanism, regulates biofilm formation, extracellular polymeric substance (EPS) production, and metabolic coordination, and may therefore provide a useful conceptual framework for addressing some of these limitations. However, most mechanistic and application-related evidence currently derives from adjacent systems, such as anaerobic digestion, activated sludge, and engineered biofilms, rather than from direct studies in livestock manure. This review examines the microbial origins of livestock odors, the limitations of conventional odor-mitigation strategies, and the potential roles of QS, quorum quenching (QQ), quorum-sensing modulation (QSM), and synthetic microbial communities (SynComs) in manure-associated odor management. Overall, we present QS-based odor regulation as a promising emerging paradigm rather than an established solution and emphasize the need for stronger in situ validation in livestock manure systems. This perspective aims to provide a microbial-level framework for future odor mitigation in livestock production.