Characterization and antimicrobial spectrum of bacteriocins produced by lactic acid bacteria isolated from traditional Bulgarian dairy products

Abstract

Aims: To isolate bacteriocin‐producing lactic acid bacteria (LAB) with high wide spectrum antibacterial activity and to characterize their inhibitory peptides. Method and Results: Seven LAB strains [Lactobacillus casei ssp. rhamnosus (PC5), Lactobacillus delbrueckii ssp. bulgaricus (BB18), Lactococcus lactis ssp. lactis (BCM5, BK15), Enterococcus faecium (MH3), Lactobacillus plantarum (BR12), Lactobacillus casei ssp. casei (BCZ2)], isolated from authentic Bulgarian dairy products were capable of producing bacteriocins, inhibiting the widest range of pathogenic bacteria. The bacteriocins were resistant to heating at 121°C for 15 min, stable at pH 2–10, sensitive to protease, insensitive to α‐amylase and lipase. Two of bacteriocins produced by Lact. bulgaricus BB18 (bulgaricin BB18) and E. faecium MH3 (enterocin MH3) were purified and the molecular masses were determined. The N‐terminal amino acid sequence of bulgaricin BB18 did not show strong homology to other known bacteriocins. Conclusions: Lactobacillus bulgaricus BB18 and E. faecium MH3 produce two novel bacteriocins highly similar to the pediocin‐like nonlantibiotics. Significance and Impact of the Study: The two bacteriocins are potential antimicrobial agents and, in conjunction with their producers, may have use in applications to contribute a positive effect on the balance of intestinal microflora. Furthermore, bulgaricin BB18 strongly inhibits Helicobacter pylori.

Anti-Infective Activities of Lactobacillus Strains in the Human Intestinal Microbiota: from Probiotics to Gastrointestinal Anti-Infectious Biotherapeutic Agents

“…It has been documented that the human probiotic intestinal microbiota L. johnsonii NCC 533, L. casei Shirota, and L. acidophilus LB display direct antagonistic activity in vitro against the gastritisassociated bacterium H. pylori ( Fig. 1 (113,(152)(153)(154). The molecule(s) present in L. acidophilus LB CFCS that exerts bactericidal activity against H. pylori remain to be identified.…”

Antagonistic effect of brevicin on Gram positive and Gram negative food borne bacteria and its biopreservative efficacy in milk

“…B. coagulans is the microorganism most frequently associated to spoilage of canned vegetables with pH between 4 and 4.5 (Mallidis et al, 1990). Nineteen indicator strains including the genera of Bacillus, Micrococcus, Listeria, Lactobacillus, Enterococcus, Leconostoc, E. coli, Pseudomonas, Salmonella, Clostridium and Pediococcus was used to screen the bacteriocin producing organisms (Simova et al, 2009). Since the isolate 5 produced greater zone of inhibition than isolate 7, 9 and 10, it was selected for further study.…”

“…It was then cooled by keeping in ice and centrifuged at 15,000 rpm for 15 min. The supernatant was collected and its pH was adjusted to 6.0 to prevent the effect of organic acids (Todorov and Dicks, 2005) and it was filter sterilized by cellulose nitrate membrane (0.45 µm, Sartorius AG, Germany) to use as a CEP (Simova et al, 2009). The different concentrations of CEP (50 and 100 µl) were analyzed for their antimicrobial activity by well diffusion assay (Tukel et al, 2007) …”

Fermentation Processes Using Lactic Acid Bacteria Producing Bacteriocins for Preservation and Improving Functional Properties of Food Products

“…Na + , K + , Li + , Cs + , Rb + and choline) leading to the destruction of proton motive force by dissipation of the transmembrane pH gradient and eventually to the cell death (Simova et al, 2009;Oppegård et al, 2007). The bactericidal or bacteriostatic activity possessed by bacteriocins is influenced by the following factors: bacteriocin dose and purification degree, physiological status of the indicator cells (e.g.…”