Effects of a bacillus-based biological modulator on Salmonella Heidelberg contamination and cecal microbiota in chickens.

Broiler litter can serve as a favorable environment for the survival and propagation of pathogens, such as Salmonella, creating negative impacts at all stages of the production chain. Given this, it is essential to seek strategies aiming to effectively control litter contamination. With the growing focus of the poultry chain on sustainability, biological treatments, like Environmental Biological Modulation (BM), have been gaining prominence. In the present study, we evaluated the in-situ effect of a Bacillus spp.-based BM on the contamination rates of Salmonella spp. in the poultry litter and the digestive tract of challenged birds, as well as its influence on the composition of the intestinal microbiota. The results showed a strong influence of the BM in reducing the frequency of positivity and the average pathogen count, both in the litter and in the birds' cecal content. Moreover, it was possible to identify significant differences in the taxonomic composition and abundance of the microbiota in the presence of the modulator. Taxa such as Streptococcus, Lactobacillus, Alistipes, and Christensenella minuta showed notable variations in the presence of BM or Salmonella contamination, being highlighted in both the analyses of classification models and network analysis. These results are important for advancing the understanding of biological tools and their contribution to sanitary and environmental control strategies. This study provides novel insights into the interplay between environmental modulation and cecal microbiota dynamics during a S. Heidelberg challenge.