Biosynthesis and FPLC purification of antibacterial peptide from the biotherapeutic agent Enterococcus faecium

Background Probiotics are microorganisms that play an essential role in microbial intestinal balance and in health care. Objective To isolate a probiotic that can be used to produce antimicrobial peptides potentially used as inhibitors against pathogenic bacteria. Materials and methods The research protocol was carried out through isolation of samples from different dairy product and screening for the most potent probiotic exhibiting antimicrobial activity against Staphylococcus aureus ATCC 6538 and Escherichia coli ATCC 8739 according to the guidelines of Clinical and Laboratory Standards Institute using the disc diffusion method. The molecular identification of this probiotic strain was done by 16S ribosomal DNA sequencing, and the phylogenetic tree was obtained. The purification process and characterization of the antibacterial peptide were done by (NH4)2SO4 and performing fast protein liquid chromatography. Results and discussion Bacterial probiotic strains obtained from different samples were screened for the best antimicrobial activity, where isolate number 9 from 18 isolates showed the highest antibacterial activity against S. aureus and E. coli. Therefore, it was chosen for molecular identification. The molecular identification process revealed that isolate number 9 was Enterococcus faecium. Results of antibiotics sensitivity indicated that S. aureus is more sensitive to antibiotics than E. coli. The fast protein liquid chromatography purification and characterization process of the peptide produced from the probiotic E. faecium showed that the active fraction was precipitated at 60% saturation of (NH4)2SO4. Moreover, single absorbance peaks confirmed the presence of the peptide ‘enterocin.’