Salmonella Thrives by Listening to Microbial Chatter in Poultry Farms

Salmonella remains one of the leading foodborne pathogens associated with poultry, and despite decades of biosecurity measures, vaccination programs, competitive exclusion products, feed additives, and antimicrobial treatments, it continues to persist across hatcheries, grow-out farms, processing facilities, and retail products. A new narrative review published in Frontiers in Bioinformatics argues that this stubborn persistence cannot be explained by the pathogen’s virulence factors alone. Instead, the author, M. Naeem of the Department of Poultry Science at Auburn University, proposes that Salmonella’s ecological success depends on its ability to participate in complex microbial communication networks that span the bird’s gut, reused litter, waterlines, hatcheries, and processing surfaces. The review, published on 26 October 2026, synthesizes current knowledge on how quorum sensing, metabolic cross-feeding, competitive exclusion, interkingdom signaling, and biofilm-associated interactions collectively govern the colonization, persistence, and transmission of Salmonella throughout poultry production systems.

The central conceptual shift advanced in the review is a move away from viewing Salmonella as an isolated pathogen and toward treating it as one participant in interconnected microbial ecosystems. The cecum, with its high microbial density and metabolic diversity, is described as the principal ecological niche for Salmonella colonization in poultry. Rather than functioning as a passive reservoir, the cecal microbiota operates as an interactive communication network in which microorganisms exchange nutrients, metabolites, signaling molecules, and antimicrobial compounds. Within this environment, Salmonella must compete for ecological niches while continuously responding to biochemical signals generated by neighboring microorganisms and host tissues. According to the review, successful colonization therefore depends on ecological compatibility with the resident microbial community rather than on pathogen abundance alone, a framing that helps explain why conventional interventions that target the pathogen directly often produce inconsistent results.

Among the communication mechanisms discussed, quorum sensing is the best characterized. Through diffusible signaling molecules known as autoinducers, bacterial populations coordinate gene expression according to cell density, synchronizing activities such as motility, biofilm development, stress resistance, and the expression of virulence-associated genes. In Salmonella, the LuxS-mediated autoinducer-2 system is described as the principal communication pathway, and because AI-2 functions as a universal bacterial signal, it allows the pathogen to monitor surrounding microbial populations and adjust its physiology to community composition. The review also describes interkingdom signaling, in which Salmonella responds to autoinducer-3 and host-derived catecholamines through sensor kinase systems such as QseC. Host stress hormones including epinephrine and norepinephrine can activate bacterial signaling pathways that enhance motility, attachment, and invasion-associated gene expression, illustrating that communication extends beyond microbial populations to direct interactions between host physiology and the pathogen.

Biofilms occupy a central place in this ecological picture. Within drinking water lines, on farm equipment, and on processing surfaces, structured microbial communities embedded in extracellular polymeric matrices facilitate nutrient sharing, stress tolerance, and cell-to-cell communication. Signaling molecules accumulate at high concentrations inside biofilms, promoting synchronized responses that enhance resistance to disinfectants, desiccation, oxidative stress, and antimicrobial agents. The review cites recent evidence of mono- and dual-species biofilm formation by Salmonella Typhimurium and Staphylococcus aureus on plastic and galvanized surfaces used in poultry houses, and comparative analyses showing that litter and waterline biofilms harbor distinct microbial compositions shaped by water quality history. The detection of Salmonella within mature waterline biofilms highlights their potential role as persistent reservoirs that contribute to flock recolonization even after cleaning procedures, complicating eradication efforts.

Beyond dedicated signaling systems, the review emphasizes indirect ecological interactions that reshape the metabolic landscape of the gut. Microbial populations producing short-chain fatty acids, vitamins, and secondary metabolites influence neighboring organisms without direct physical contact. Butyrate and propionate produced by anaerobic fermentative bacteria have been associated with reduced invasion gene expression and enhanced colonization resistance. Ex vivo studies comparing permissive and exclusive cecal communities found profound differences in Salmonella metabolism and virulence gene expression, including suppression of SPI-1-associated genes and altered propanediol and vitamin B12 metabolism in restrictive communities. Inoculation of broiler chicks with defined microbial consortia increased microbial diversity, reduced Enterobacteriaceae abundance, altered short-chain fatty acid production, and suppressed Salmonella colonization, and the inclusion of the taxon Megamonas hypermegale altered fermentation patterns while reducing pathogen abundance.

The review is careful to distinguish the strength of evidence behind these mechanisms. Poultry studies provide direct experimental support for competitive exclusion, metabolic restriction, and microbiota-mediated suppression of Salmonella, whereas evidence for some broader community-level interactions derives from associations between microbial composition, metabolite profiles, and pathogen abundance. Reductions in Salmonella following microbiome manipulation cannot necessarily be attributed to microbial diversity alone, because community composition, metabolic function, host responses, bird age, diet, and environmental conditions may contribute simultaneously. Similarly, while oxygen depletion, pH alteration, iron sequestration, and bile acid modification can influence Salmonella physiology, several mechanistic demonstrations come from mammalian or in vitro models rather than poultry, and evidence that resident poultry microbiota suppress the pathogen specifically through these routes remains uneven. Associations between particular communities and reduced Salmonella abundance, the author stresses, should not be conflated with experimentally demonstrated causal mechanisms.

Environmental reservoirs receive substantial attention as active ecosystems rather than mere contamination sources. Reused poultry litter contains diverse microbial populations whose composition shifts with moisture, pH, ammonia concentration, and management practices, generating conditions that influence Salmonella persistence. Network analyses have identified specific bacterial taxa associated with reduced Salmonella abundance, and Bacillus subtilis consortia isolated from litter have exhibited inhibitory activity against Salmonella Heidelberg. Hatcheries constitute another critical interface, where biomapping studies have revealed considerable serotype diversity, indicating stable microbial reservoirs capable of introducing pathogens at the earliest stages of production. Early microbial colonization by pioneer species shapes subsequent succession and community assembly, contributing to colonization resistance by limiting ecological opportunities for invading pathogens. The review also treats horizontal gene transfer as a related but distinct evolutionary process: poultry-derived Salmonella isolates have been shown to harbor plasmids carrying antimicrobial-resistance and virulence genes with potential for conjugative transfer, a heritable genetic exchange rather than signal-mediated communication.

These ecological insights motivate a suite of emerging, ecosystem-based control strategies. Competitive exclusion remains the most successful example, having evolved from administering intestinal contents of healthy adult birds into rationally designed defined consortia that compete for nutrients and attachment sites, produce antimicrobial compounds, alter metabolite profiles, and modulate host immunity. Prebiotics such as galacto-oligosaccharides, particularly when combined with attenuated Salmonella strains, have been shown to modify gut microbial composition and accelerate pathogen clearance, while the probiotic Lactobacillus paracasei suppressed Salmonella Pullorum while restoring microbial diversity in infected chickens. Quorum-quenching compounds derived from plants, microorganisms, enzymes, and synthetic chemistry can degrade autoinducers or block receptor activation, potentially reducing biofilm formation and virulence expression with less selective pressure for antimicrobial resistance than conventional antibiotics. Bacteriophage therapy, biofilm-disrupting enzymes, and antimicrobial peptides round out the intervention toolkit, with phages offering narrow host specificity that minimizes collateral disruption of communities that contribute to colonization resistance.

The review tempers enthusiasm with explicit limitations. Much of the quorum-quenching evidence comes from in vitro studies, and activity observed under controlled conditions may not reproduce within complex intestinal microbiota, established multispecies biofilms, or variable production environments. Efficacy may depend on compound stability, concentration, delivery, and accessibility, interference with conserved signaling systems could affect non-target microbiota, and resistance to quorum-sensing inhibitors can evolve through altered receptors or increased efflux. Quorum quenching is therefore positioned as a promising complementary strategy rather than a stand-alone replacement for established measures. Looking forward, the author argues that future research should move beyond 16S rRNA-based compositional surveys toward metagenomics, metatranscriptomics, metaproteomics, metabolomics, ecological network analysis, spatial transcriptomics, and single-cell sequencing to identify keystone taxa and critical signaling pathways. From a One Health perspective, strengthening microbial communication networks and ecosystem resilience, rather than pursuing complete eradication of Salmonella, may offer a more sustainable route to keeping pathogen populations below thresholds associated with disease transmission and food safety risk.

Subject of Research: Microbial communication networks that regulate Salmonella colonization and persistence in poultry production systems and emerging microbiome-based control strategies

Article Title: Microbial communication networks governing the ecosystem dynamics of Salmonella in poultry environments: ecological interactions, colonization resistance, and emerging control strategies

Article References: Naeem, M. (2026). Microbial communication networks governing the ecosystem dynamics of Salmonella in poultry environments: ecological interactions, colonization resistance, and emerging control strategies. Frontiers in Bioinformatics, 6, Article 1908527. https://doi.org/10.3389/fbinf.2026.1908527

Image Credits: AI Generated

DOI: 10.3389/fbinf.2026.1908527

Keywords: Salmonella, poultry, microbiome, quorum sensing, biofilms, colonization resistance, competitive exclusion, probiotics, prebiotics, quorum quenching, One Health, food safety