Lactobacillus salivarius: bacteriocin and probiotic activity.

Lactic acid bacteria (LAB) antimicrobial peptides typically exhibit antibacterial activity against food-borne pathogens, as well as spoilage bacteria. Therefore, they have attracted the greatest attention as tools for food biopreservation. In some countries LAB are already extensively used as probiotics in food processing and preservation. LAB derived bacteriocins have been utilized as oral, topical antibiotics or disinfectants. Lactobacillus salivarius is a promising probiotic candidate commonly isolated from human, porcine, and avian gastrointestinal tracts (GIT), many of which are producers of unmodified bacteriocins of sub-classes IIa, IIb and IId. It is a well-characterized bacteriocin producer and probiotic organism. Bacteriocins may facilitate the introduction of a producer into an established niche, directly inhibit the invasion of competing strains or pathogens, or modulate the composition of the microbiota and influence the host immune system. This review gives an up-to-date overview of all L. salivarius strains, isolated from different origins, known as bacteriocin producing and/or potential probiotic.

In vitro evaluation of the probiotic potential of Lactobacillus salivarius SMXD51.

Lactobacillus salivarius SMXD51 was previously isolated from the cecum of a Tunisian poultry and found to produce a bacteriocin-like substance highly active against the foodborne pathogen Campylobacter jejuni. The aim of this study was to examine some probiotic properties of the strain: acid and bile tolerance, capacity of adhesion, stimulation of immune defences (IL-6, IL-8, IL-10 and ß-defensin 2), and modulation of the barrier integrity. The results showed that L. salivarius SMXD51 can tolerate gastrointestinal conditions (acid and bile), adhere to intestinal cells and stimulate the immune system. The bacterium strengthened the intestinal barrier functions through the increase of the transepithelial electrical resistance (TEER) and reinforcement of the F-actin cytoskeleton. One hour pretreatment with L. salivarius SMXD51 protected against Pseudomonas aeruginosa PAO1-induced decrease of TEER and damage of the F-actin cytoskeleton. Our results highlight that L. salivarius SMXD51 fulfils the principle requirements of an efficient probiotic and may be seen as a reliable candidate for further validation studies in chicken.

Effects of divercin V41 combined to NaCl content, phenol (liquid smoke) concentration and pH on Listeria monocytogenes ScottA growth in BHI broth by an experimental design approach.

AIMS: To investigate the main effects and interactions of different factors : divercin V41 (0-4 ng ml(-1)), NaCl content (0.5-5.5% w v(-1)), phenol (liquid smoke) concentration (0-8 ppm), and pH (5.5-7.5) on Listeria monocytogenes ScottA growth. METHODS AND RESULTS: Experiments were carried out in BHI broth using a central composite design. Divercin V41 (div41), NaCl content and pH were found to be the most influential factors whereas phenol concentration in liquid smoke had no effect on L. monocytogenes ScottA growth in our experimental domain. The combined effects of div41, NaCl content and pH decreased L. monocytogenes ScottA maximum specific growth rate (mu(max)) from 0.34 to 0.01 h(-1) and led to a significant increase in lag time (t(lag)) from 5.5 to 25 h. CONCLUSION: In this study, NaCl, pH and phenol conditions were similar to those currently observed in smoked salmon production. This shows that L. monocytogenes ScottA growth could be efficiently delayed by the use of div41 in addition to the usual technological hurdles. SIGNIFICANCE AND IMPACT OF THE STUDY: In conclusion, the technological hurdles of cold smoked salmon production could be further optimized and combined with the use of div41 or the div41 producer strain to improve the food safety of the product.

Production of biogenic amines and divercin V41 in cold smoked salmon inoculated with Carnobacterium divergens V41, and specific detection of this strain by multiplex-PCR.

AIMS: The objective of this study was to determine the technological behaviour (implantation and biogenic amines production) of Carnobacterium divergens V41, an anti-Listeria bacteriocin producer (divercin V41), after inoculation in cold smoked salmon (CSS). METHODS AND RESULTS: Implantation of the strain was followed by multiplex-PCR during 27 days of storage at 4 degrees C, and biogenic amines were quantified by HPLC. It was found that the strain was able to develop quite well in CSS among lactic wild flora. Divercin V41 (400 AU ml-1) was produced in CSS, and the biogenic amine content was not modified by inoculation of the bacteria. CONCLUSIONS: Carnobacterium divergens V41 is a safe, interesting, bioprotective agent. SIGNIFICANCE AND IMPACT OF THE STUDY: This strain could potentially be used for efficient prevention of L. monocytogenes growth in CSS.

Enumeration of Carnobacterium divergens V41, Carnobacterium piscicola V1 and Lactobacillus brevis LB62 by in situ hybridization-flow cytometry.

The specific detection and enumeration of Lactobacillus brevis LB62, Carnobacterium divergens V14 and Carnobacterium piscicola VI were studied by in situ hybridization-flow cytometry. The method was performed on the exponential growth phase with three probes targeting 16S rRNA labelled with fluorescein isothicyanate (FITC): EUB338 probe universal for Eubacteria, Lb probe specific for Lact. brevis and Cb probe specific for the genus Carnobacterium. EUB338 was used to determine the permeabilization and hybridization conditions for the cells. The Lb probe gave no hybridization signal whereas the Cb probe allowed the detection and quantification by flow cytometry at 520 nm of the two Carnobacterium strains in pure culture or in mixtures with Listeria innocua F.