Identification of a microbial sub-community from the feral chicken gut that reduces Salmonella colonization and improves gut health in a gnotobiotic chicken model

A complex microbial community in the gut may prevent the colonization of enteric pathogens such as . Some individual or a combination of species in the gut may confer colonization resistance against . To gain a better understanding of the colonization resistance against , we isolated a library of 1,300 bacterial strains from feral chicken gut microbiota which represented a total of 51 species. Using a co-culture assay, we screened the representative species from this library and identified 30 species that inhibited subspecies enterica serovar Typhimurium . To improve the inhibition capacity, from a pool of fast-growing species, we formulated 66 bacterial blends, each of which composed of 10 species. Bacterial blends were more efficient in inhibiting as compared to individual species. The blend that showed maximum inhibition (Mix10) also inhibited other serotypes of frequently found in poultry. The effect of Mix10 was examined in a gnotobiotic and conventional chicken model. The Mix10 consortium significantly reduced load at day 2 post-infection in gnotobiotic chicken model and decreased intestinal tissue damage and inflammation in both models. Cell-free supernatant of Mix10 did not show inhibition, indicating that Mix10 inhibits through either nutritional competition, competitive exclusion, or through reinforcement of host immunity. Out of 10 species, 3 species in Mix10 did not colonize, while 3 species constituted more than 70% of the community. Two of these species were previously uncultured bacteria. Our approach could be used as a high-throughput screening system to identify additional bacterial sub-communities that confer colonization resistance against enteric pathogens and its effect on the host.IMPORTANCE colonization in chicken and human infections originating from contaminated poultry is a significant problem. Poultry has been identified as the most common food linked to enteric pathogen outbreaks in the United States. Since multi-drug-resistant often colonize chicken and cause human infections, methods to control colonization in poultry are needed. The method we describe here could form the basis of developing gut microbiota-derived bacterial blends as a microbial ecosystem therapeutic against .