Staphylococcus xylosus VITURAJ10: Pyrrolo [1,2α] pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl) (PPDHMP) producing, potential probiotic strain with antibacterial and anticancer activity.

In the present study bacterial strain (VITURAJ10), isolated from goat milk was characterised for its probiotic potential. The various probiotic traits included tolerance to acidic pH (up to pH 3), bile salts (0.3%) and transit gut environment (simulated with digestive juices such as pepsin, Oxgall and pancreatin). The isolate could withstand high NaCl concentrations in the growth medium, showed inability to produce hemolysin and did not hydrolyse mucin. VITURAJ10 was capable of forming biofilm and produced exopolysachharide. The bioactive metabolites produced by the isolate were extracted and they showed growth suppressing activity towards pathogenic strains such as Escherichia coli, Salmonella enterica and Staphylococcus aureus. The crude extract was fractionated with solid phase extraction (SPE) chromatography and the fractions 10 and 12 were found to be effective against the bacterial pathogens. The fractions were further gauged for cytotoxic activity against MCF-7 cell line by MTT assay. The biologically significant compounds identified through GC-MS and FT-IR analysis in the fractions were, Actinomycin D, Pyrrolo [1,2α] Pyrazine-1,4-Dione, Hexahydro-3-(2-Methylpropyl)- (PPDHMP) and Didemnin B. The phylogenetic taxonomy of the isolate revealed the isolate to be the closest neighbour of Staphylococcus xylosus VITURAJ10 (GenBank accession no. KX770743.1) as per the16S rRNA gene sequencing and subsequent phylogenetic tree analysis.