Uncovering how selected potent bacteriocins reshape the broiler chicken gut microbiome in a PolyFermS continuous in vitro model.

Abstract

Background: Bacteriocins are promising alternatives to antibiotics in poultry production, offering pathogen control with minimal disruption to gut microbiota and reduced risk of resistance dissemination. This study compared the impact of three bacteriocins-microcin J25, nisin Z, and pediocin PA-1-against bacitracin as a positive control, specifically evaluating their effects on gut microbiota composition and metabolic activity. The study utilized the PolyFermS continuous fermentation model to simulate chicken caecal conditions.

Results: 16S rRNA sequencing revealed that bacitracin and nisin Z significantly altered the microbiota composition, reducing key families such as Lactobacillaceae and Ruminococcaceae, while microcin J25 and pediocin PA-1 had negligible effects. Short-chain fatty acid analysis revealed a significant time-dependent decrease in butyrate levels following nisin Z and bacitracin treatments, with the most pronounced reduction observed at 48 h post-injection. Conversely, microcin J25 and pediocin PA-1 maintained stable profiles. Untargeted LC-MS metabolomics indicated a marked metabolic shift under nisin Z treatment, including increased amino acids and cyclic dipeptide levels, while microcin J25 had minimal impact. Stability assays confirmed that microcin J25 remained active up to 24 h, whereas nisin Z and pediocin PA-1 lost antimicrobial activity rapidly.

Conclusions: These findings support the selective use of bacteriocins as alternatives to antibiotics in poultry farming, with microcin J25 demonstrating the most favorable profile for microbiota preservation and metabolic stability. Future research will focus on in vivo trials in broiler chickens to confirm these findings and evaluate the practical application of microcin J25 in a production environment.