Antimicrobial activity of bacteriocin produced by a new Latilactobacillus curvatus sp.LAB-3H isolated from traditional yogurt

In recent years, the use of bacteriocin-producing Lactobacillus species has received much attention in different areas, including using as probiotics, food preservation, and as broad antimicrobial spectrum activity. In this study, a bacteriocin-producing Lactobacillus strain was isolated from traditional yogurt. The isolate was identified by morphological, biochemical, 16S rRNA analyses, and designated as Latilactobacillus curvatus LAB-3H. The primary antimicrobial activity of the isolate was evaluated on Micrococcus luteus PTCC 1408 by the agar gel diffusion method. The growth of L. curvatus LAB-3H in MRS broth at 37 degrees C and its antimicrobial activity against Lactobacillus casei ATCC 39,392 was evaluated. In batch culture analysis, bacteriocin production starts at the early exponential growth phase and continues to the middle of the stationary phase about (660 AU/ml) at 28 h and pH 3.8. Bacteriocin produced by L. curvatus LAB-3H showed antibacterial activity against some selected foodborne pathogens, including Listeria monocytogenes PTCC1294, Bacillus cereus PTCC1857, Staphylococcus aureus PTCC1917, and Escherichia coli PTCC1276. For purification of bacteriocin, ammonium sulfate precipitation and cation exchange chromatography methods were used. The maximum antimicrobial activity observed was about 3985.15 AU/mg of protein, which was a 249.22-fold increase, and 5.21% yield compared with that in the cell-free supernatant. The molecular weight of bacteriocin was approximately 55 kDa by SDS-PAGE. The obtained results in this study demonstrate that bacteriocin from L. curvatus LAB-3H is a potential candidate for controlling microbial contaminations and can be used in different sectors, such as food industries.