A potential probiotic culture ST2 produces siderophore 2,3-dihydroxybenzoylserine under intestinal conditions.

The aim of this study was to characterise siderophores of a culture bearing better probiotic qualities of human origin. In this direction, bacterial strain ST2 was isolated from faecal sample of 6-month-old healthy infant, which showed close similarity with Escherichia coli based on 16S r-RNA gene sequence analysis and biochemical characteristics. It was tested for siderophore production under in vitro iron limiting intestinal conditions. The siderophore produced was catecholate type of 2,3-dihydroxybenzoylserine on the basis of FTIR, NMR and mass spectra analysis. The strain obeyed probiotic properties as per WHO and FAO guidelines. It showed excellent tolerance in partially simulated gastro-intestinal tract conditions, non-haemolytic nature, susceptibility to many antibiotics tested and antimicrobial activity against enteric pathogens like Salmonella typhimurium, Streptococcus pyogenes, and Staphylococcus aureus. Hence, this culture could be a possible probiotic candidate in iron nutrition, but only after conducting proper animal and human trials.