Novel bacteriocins produced by Lactobacillus fermentum strains with bacteriostatic effects in milk against selected indicator microorganisms

The aim of this work was to isolate and characterize bacteriocins produced by 2 Lactobacillus fermentum strains isolated from artisanal Mexican Cocido cheese. Fractions (F ≤3 kDa) obtained cell-free supernatants Lb. J23 J32 were further fractionated reversed-phase HPLC on a C18 column. Antimicrobial activities F kDa bacteriocin-containing fractions (BCF), fractionation against 4 indicator microorganisms, determined the disk diffusion method growth inhibition in milk. Subsequently, BCF analyzed tandem mass spectrometry. Results showed that presented antimicrobial activity microorganisms tested. For J23, one (F3) highest Escherichia coli also inhibitory Staphylococcus aureus, Listeria innocua, Salmonella Typhimurium, Choleraesuis. Similarly, F3 F4 all microorganisms. Furthermore, generation time rate significantly higher (2 gram-positive gram-negative) when inoculated milk compared with J32. Interestingly, fraction broader spectrum than nisin (control). Reversed-phase spectrometry analysis revealed presence several peptides BCF; however, most active only 1 bacteriocin. chemical characterization bacteriocin suggested it novel peptide 10 hydrophobic AA residues its sequence molecular weight 2,056 Da. This producing strain, may find application as biopreservative these dairy products.