Antimicrobial activity of bifidobacteria against clostridia species colonizing the digestive tract of infants

Bifidobacterium spp. are dominant taxa of infant microbiota and can protect the host from enteropathogenic infections through acetate production or other mechanisms. Whereas the sporulating clostridia include variable species, from health-promoting butyrate-producing bacteria with the probiotic potential to highly pathogenic bacteria. The presence and activity of potentially dangerous sporulating bacteria in the intestinal microbiota of infants is considered to underlie the etiology of gastrointestinal disorders, such as enterocolitis necrotizing. Most of the published work focuses on the interactions of bifidobacteria with Clostridium perfringens, C. butyricum and C. difficile, but little is known about C. tertium, C. neonatale and others. We assume that the antimicrobial activity of bifidobacteria against pathogenic or commensal clostridia will be species- or strain-specific. Also, variability between the sensitivity of Clostridium spp. will also be found here. The aim of the thesis will be to prepare an overview about bifidobacteria and clostridia occurring in the digestive tract of infants, including the current findings on their interaction, mainly focused on antimicrobial activity. Strains from the collection of the Department of Microbiology, Nutrition and Dietetics, Czech University of Life Sciences Prague (CZU, Prague) as well as commercial strains from probiotic products and official type strains obtained from the German Collection of Microorganism and Cell Cultures (DSMZ) will be used for testing. The identity of the strains will be verified using MALDI-TOF MS, while the antimicrobial activity testing will be done using the diffusion method, the agar spot test, and the inhibition of gas production.