Characterisation of spore forming Bacilli isolated from the human gastrointestinal tract

Aims: To isolate and characterize spore-former bacteria able to colonize thehuman gastrointestinal tract (GIT). Methods and Results: A total of 25 spore-formers was isolated from faeces and ileal biopsies of healthy human volunteers and identified at the species level. Physiological analysis was performed to evaluate the ability of the various isolates to form biofilms, to swarm, to produce surfactants and molecules that have antimicrobial activity against selected pathogens. To assess the potential probiotic activity of the isolates, we tested the resistance of cells and spores to simulated gastric conditions, the ability to grow and sporulate in anaerobic conditions and the presence of toxin-encoding genes in their genome. Conclusions: Spore-formers belonging to various bacterial species have been isolated from the gut of healthy human volunteers. These strains appear to be well adapted to the intestinal environment and we propose them as potential probiotic strains for human use and as oral vaccine vehicles. Significance and Impact of the Study: To our knowledge this is the first detailed characterization of spore-forming Bacilli from the human GIT. Our data suggest that the isolated species do not transit, but rather colonize this specific habitat and propose them as probiotic strains for human use.