Safety evaluation of Lactobacillus paracasei subsp. paracasei LC-01, a probiotic bacterium

The safety of Lactobacillus paracasei subsp. paracasei LC-01 was evaluated for its use as a potential probiotic. In our in vitro study, the antibiotic resistance and the ability to produce biogenic amine were determined. The results showed that the strain was sensitive to all tested antibiotics and did not produce biogenic amine except for tyramine. The oral toxicity of this strain was evaluated in Balb/C mice. One hundred mice were divided into 10 groups. Four groups were administered 0, 10⁸, 10⁹, or 10¹⁰ CFU/mouse per day dissolved in saline solution respectively, for 28 days. Three groups were injected intraperitoneally with 10⁹ CFU/mouse dissolved in saline solution, and were killed 2, 5, and 10 days after injection. The last 3 groups were injected with the vehicle as controls respectively. The results showed that oral administration of the strain had no adverse effects on mouse body weight and that there was no treatment-associated bacterial translocation. Intraperitoneal administration caused a significant translocation to liver, spleen and kidney. However, this translocation did not cause illness or death throughout the experiment. The results suggest that L. paracasei subsp. paracasei LC-01 is likely to be safe for human consumption.     

Evaluation of Lactobacillus paracasei subsp. tolerans isolated from Jenyn's sprat (Ramnogaster arcuata) as probiotic for juvenile rainbow trout Oncorhynchus mykiss (Walbaum, 1792)

A lactic acid bacterial strain, Lactobacillus paracasei subsp. tolerans F2, isolated from the intestine of Ramnogaster arcuata, was evaluated as a growth promoter in juvenile rainbow trout Oncorhynchus mykiss (Walbaum, 1972) farming. In addition, the safety of the strain was assessed according to the FAO recommendations. Strain F2 was susceptible to most antibiotics tested and no evidence of hemolytic activity was found. When the strain of Lactobacillus paracasei subsp. tolerans F2 was administered with food, no adverse effects on health were observed and fish biomass increased 12% more in the treatment group than in the control group. Significant differences were detected in the specific growth rate and feed conversion ratio. In the group receiving Lactobacillus paracasei subsp. tolerans F2‐supplemented feed, quantitative differences in the microbial composition of fish feces with respect to the control group were observed. An important decrease in fungi and enterobacteria was observed in feces from the treatment group, coincident with an increase in lactic acid bacteria. This result would indicate a change in the composition of the intestinal microbiota of fish treated with the putative probiotic. These results suggest that the strain of Lactobacillus paracasei subsp. tolerans F2 has the application potential to improve the performance in rainbow trout farming.     

Selection of Escherichia coli-inhibiting strains of Lactobacillus paracasei subsp. paracasei

The aim of this study was to select Escherichia coli-inhibiting strains among lactic acid bacteria. On the basis of phenotypical and technological characteristics, 20 strains of lactic acid bacteria were screened from a total of 225 isolates, obtained from nine samples of artisanal Caprino d'Aspromonte cheese, made from raw goats' milk. The antagonistic activity of these 20 strains was detected in plates against three different strains of E. coli. Two strains of Lactobacillus paracasei subsp. paracasei showed a marked anti-E. coli activity against all three strains tested; the other lactic acid bacteria did not exhibit inhibiting activity. The E. coli inhibition can be ascribed to production of bacteriocin-like compounds. The use of L. paracasei subsp. paracasei strains to increase the safety of the cheeses made from raw milk is recommended because these cultures strongly inhibit E. coli, without foreseeable adverse sensory changes. Received 27 December 2001/ Accepted in revised form 28 June 2002     

Milk Fermented by Lactobacillus paracasei NCC 2461 (ST11) Modulates the Immune Response and Microbiota to Exert its Protective Effects Against Salmonella typhimurium Infection in Mice

Probiotics form a promising strategy to maintain intestinal health. Milks fermented with probiotic strains, such as the Lactobacillus paracasei ST11, are largely commercialized in Brazil and form a low-cost alternative to probiotic pharmaceutical formulations. In this study, we assessed the probiotic effects of milk fermented by L. paracasei ST11 (administered through fermented milk) in a Salmonella typhimurium infection model in BALB/c mice. We observed in this murine model that the applied probiotic conferred protective effects against S. typhimurium infection, since its administration reduced mortality, weight loss, translocation to target organs (liver and spleen) and ileum injury. Moreover, a reduction in the mRNA expression of pro-inflammatory cytokines such as IFN-γ, IL-6, TNF-α and IL-17 in animals that received the probiotic before challenge was observed. Additionally, the ileum microbiota was better preserved in these animals. The present study highlights a multifactorial protective aspect of this commercial probiotic strain against a common gastrointestinal pathogen.

     

Antagonistic Activity of Potential Probiotic Lactobacilli Against the Ureolytic Pathogen Yersinia enterocolitica

Strains of Lactobacillus spp., isolated from sourdough and olive brines (seven strains), and three human isolates were screened for their antagonistic activity in coculture against the ureolytic pathogen Yersinia enterocolitica. A general reduction in the pathogen population was observed after 6 h when each Lactobacillus strain was cocultured with the pathogen at a ratio of 100:1 cfu ml⁻¹, causing an almost complete inhibition of urease activity. Strains were also screened for their performances in in vitro tests such as adhesion ability to Caco-2 cells, tolerance to low pH, bile salts, and simulated digestion, which enabled the differences between strains to be highlighted. Three strains, L. paracasei IMPC2.1 and L. plantarum ITM21B and ITM5BG, met the main criteria for selecting effective probiotics: the ability to inhibit the pathogen Y. enterocolitica and, consequently, its urease activity (ITM21B); survival of simulated digestion (ITM21B and IMPC2.1); strong adhesion ability to enterocytes and good survival at low pH and in the presence of bile salts (ITM5BG and IMPC2.1).     

Fermentation of a milk-soymilk and Lycium chinense Miller mixture using a new isolate of Lactobacillus paracasei subsp. paracasei NTU101 and Bifidobacterium longum

A milk–soymilk mixture was fermented using Lactobacillus paracasei subsp. paracasei NTU101 and Bifidobacterium longum BCRC11847 at different inoculum ratios (1:1, 1:2, 1:5, 2:1, and 5:1). When the inoculum ratio was 1:2, the cell numbers of both strains were balanced after 12 h of cultivation. The pH and titratable acidity were very similar at the various inoculum ratios of cultivation. The milk–soymilk mixture was supplemented with 5, 10, 15, and 20% Lycium chinense Miller juice and fermented with Lactobacillus paracasei subsp. paracasei NTU101 and B. longum BCRC11847. Sensory evaluation results showed that supplementation with 5% Lycium chinense Miller juice improved the acceptability of the fermented milk–soymilk. The fermented beverage was stored at 4°C for 14 days; variations in pH and titratable acidity were slight. The cell numbers of L. paracasei subsp. paracasei NTU101 and B. longum BCRC11847 in the fermented beverage were maintained at 1.2×10⁹ CFU/ml and 6.3×10⁸ CFU/ml, respectively, after 14 days of storage.     

Lactobacillus paracasei subsp. paracasei LC01 positively modulates intestinal microflora in healthy young adults

Lactobacillus paracasei subsp. paracasei LC01 (LC01) can tolerate intestinal stresses and has antioxidant activity. To evaluate the effect of the bacterium on human intestinal microflora, a randomized, double-blind, placebo-controlled human trial was carried out. Fifty-two healthy adult volunteers were randomized equally to two groups. One group consumed 12% (wt/vol) skimmed milk supplemented with 10¹⁰ CFU of LC01 each day for the 4-week treatment period, and then consumed placebo in the next treatment period, separated by a 2-week washout. The other group followed the reverse order. Group-specific real-time PCR and biochemical analyses was used to determine the intestinal bacterial composition of fecal samples collected at the end of every period, and the concentration of short-chain fatty acids and ammonia. A significant inhibition in fecal Escherichia coli and increase in Lactobacillus, Bifidobacterium, and Roseburia intestinalis were observed after consumption of LC01. Acetic acid and butyric acid were significantly higher in the probiotic stage and fecal ammonia was significantly lower. The results indicated a modulation effect of LC01 on the intestinal microflora of young adults, suggesting a beneficial effect on bowel health. LC01 may have potential value as a probiotic.     

Role of the probiotic strain Lactobacillus paracasei LMGP22043 carried by artichokes in influencing faecal bacteria and biochemical parameters in human subjects

Aims: To evaluate the positive influence of the probiotic strain Lactobacillus paracasei LMGP22043 carried by artichokes into the human gut with special reference to faecal bacterial balance, short‐chain fatty acid concentrations and enzyme activities in a randomized, double‐blind human trial in comparison with probiotic‐free artichokes (control). Methods: Twenty subjects were randomized into two groups, which consumed daily 180 g of the artichoke product (probiotic or control) during two 15‐day study periods (periods 1 and 2) separated by a 15‐day washout in a crossover manner. Faecal samples were subjected to microbiological and biochemical analyses, and a strain‐specific PCR was performed to monitor the probiotic strain. Results: The probiotic strain, transported by the vegetable matrix, transiently colonized the gut of 17/20 subjects (median 6·87 log CFU g^?1 faeces), antagonized Escherichia coli and Clostridium spp. and increased the genetic diversity of lactic population based on REP‐PCR profiles, mainly after period 1. Conclusions: The probiotic L. paracasei LMGP22043 successfully colonized the human gut and positively influenced faecal bacteria and biochemical parameters. Significance and Impact of the Study: The association of the probiotic L. paracasei with a food carrier rich in fibre can represent a new strategy for favouring a daily supply of probiotics and attracting more consumers to vegetable food fortified with probiotic strains.     

Survival of Lactobacillus paracasei subsp. paracasei LBC 81 in Fermented Milk Enriched with Green Banana Pulp Under Acid Stress and in the Presence of Bile Salts

This study evaluated the in vitro effect of 3.0, 6.0, and 9.0% of green banana pulp (GBP) incorporation in fermented milk on the survival of Lactobacillus paracasei subsp. paracasei LBC 81 subjected to acid stress conditions and in the presence of bile salts. Tolerance to acid stress in pH 2.0 and in the presence of 0.30% of bile salts was evaluated right after the incorporation of the fermented milk in each of these conditions, and also during 3 and 4 h of exposure, respectively. The addition of GBP (3.0%) gives a protective effect on L. paracasei LBC 81 when exposed to stress conditions evaluated, while of 9.0% there is a marked decrease of L. paracasei LBC 81. In the absence of GBP, a decrease of L. paracasei LBC 81 is observed, but lower in the presence of GBP (9.0%).

     

Antimicrobial and antiadhesive properties of a biosurfactant isolated from Lactobacillus paracasei ssp. paracasei A20

Aims: The aim of this study was to determine the antimicrobial and antiadhesive properties of a biosurfactant isolated from Lactobacillus paracasei ssp. paracasei A20 against several micro‐organisms, including Gram‐positive and Gram‐negative bacteria, yeasts and filamentous fungi. Methods and Results: Antimicrobial and antiadhesive activities were determined using the microdilution method in 96‐well culture plates. The biosurfactant showed antimicrobial activity against all the micro‐organisms assayed, and for twelve of the eighteen micro‐organisms (including the pathogenic Candida albicans, Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Streptococcus agalactiae), the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) were achieved for biosurfactant concentrations between 25 and 50 mg ml^?1. Furthermore, the biosurfactant showed antiadhesive activity against most of the micro‐organisms evaluated. Conclusions: As far as we know, this is the first compilation of data on antimicrobial and antiadhesive activities of biosurfactants obtained from lactobacilli against such a broad group of micro‐organisms. Although the antiadhesive activity of biosurfactants isolated from lactic acid bacteria has been widely reported, their antimicrobial activity is quite unusual and has been described only in a few strains. Significance and Impact of the Study: The results obtained in this study regarding the antimicrobial and antiadhesive properties of this biosurfactant opens future prospects for its use against micro‐organisms responsible for diseases and infections in the urinary, vaginal and gastrointestinal tracts, as well as in the skin, making it a suitable alternative to conventional antibiotics.     

Stabilization of freeze-dried Lactobacillus paracasei subsp. paracasei JCM 8130T with the addition of disaccharides,polymers, and their mixtures

Although freeze-drying is a widely used dehydration technique for the stabilizing of unstable lactic acid bacteria, Lactobacillus paracasei subsp. paracasei JCM 8130^T (L. paracasei) is destabilized after freeze-drying and subsequent storage. In order to improve the stability of freeze-dried L. paracasei, effects of disaccharides (sucrose and trehalose), polymers (maltodextrin; MD and bovine serum albumin; BSA), and their mixtures on the survival rate of freeze-dried L. paracasei were investigated. The survival rate of non-additive sample decreased slightly after freeze-drying but decreased drastically after subsequent storage at 37 °C for 4 weeks. The reduction was diminished by the addition of disaccharides and polymers. The stabilizing effect of disaccharides was not affected by the co-addition of MD. In contrast, the disaccharide–BSA mixtures had a synergistic stabilizing effect, and the survival rates were largely maintained even after storage. It is suggested that the synergistic effect originates from the conformational stabilization of the dehydrated bacteria.     

1H NMR investigation on the role of sorbitol for the survival of Lactobacillus paracasei ssp. paracasei in vacuum‐dried preparations

Aims: The aim of this work was to study the effect of sorbitol as protective agent on the survival of the probiotic strain Lactobacillus paracasei ssp. paracasei (F19) after vacuum drying. Methods and Results: The survival was studied after different drying times and for various concentrations of sorbitol by plate count method. Furthermore, time domain ¹H NMR studies on dehydrated suspensions of Lact. paracasei ssp. paracasei were performed to study the proton mobility in the dried samples. From the obtained signal, T2 relaxation times of single components and fractions with different proton mobility were determined. It was found out that the survival is increased by the presence of a minimum amount of sorbitol that is dependent on drying time. Furthermore, it is shown that the protective effect can only be observed below a critical water content of c. 20%. Nuclear magnetic resonance (NMR) results indicate a transition of sorbitol from liquid to solid like behaviour during drying. The onset of the transition coincides with the critical water content found for a protective effect. Conclusions: The data suggest that sorbitol protons are incorporated into the dried cells of Lact. paracasei ssp. paracasei (F19) below the critical water content and therefore leading to an enhanced survival. Significance and Impact of the Study: The results help to better understand the underlying mechanism of protection of Lact. paracasei ssp. paracasei using sorbitol and to establish vacuum drying as potential alternative drying technique to standard freeze drying.     

Characterization and purification of a bacteriocin from <Emphasis Type="Italic">Lactobacillus paracasei</Emphasis> subsp. <Emphasis Type="Italic">paracasei</Emphasis> BMK2005, an intestinal isolate active against multidrug-resistant pathogens

A strain of Lactobacillus paracasei subsp. paracasei BMK2005 isolated from healthy infant faeces has shown a remarkable antibacterial activity against 32 bacterial pathogenic strains of human clinical isolates. Among them, 13 strains belonging to species of Escherichia coli, Citrobacter freundii, Citrobacter diversus, Klebsiella oxytoca, Enterobacter cloacae and Pseudomonas aeruginosa were resistant to Cefotaxime (CTX) and Ceftazidime (CAZ), and 4 strains of Staphylococcus aureus were resistant to Methicillin (MRSA). This antibacterial activity was attributed to a bacteriocin designated as Paracaseicin A. It was heat-stable up to 120°C for 5 min and active within the pH range of 2–5. Its activity was lost when treated with proteases, which reveals its proteinaceous nature. This bacteriocin was successfully purified only by two steps of reversed phase chromatography. Its molecular mass, determined by mass spectrometry analysis, was 2,462.5 Da. To our knowledge, the present study is the first report on characterization and purification of a bacteriocin, produced by a L. paracasei subsp. paracasei strain exhibiting an antibacterial activity against various multidrug-resistant species of Gram-positive and Gram-negative bacteria, which reveals its potential for use in prevention or treatment of infections caused by multidrug-resistant species especially in cases of antibiotics-associated diarrhea (AAD).     

Bactericidal and non-cytotoxic activity of bacteriocin produced by Lacticaseibacillus paracasei F9-02 and evaluation of its tolerance to various physico-chemical conditions

This study aims to explore novel lactic acid bacteria (LAB) from breast-fed infants' faeces towards characterizing their antimicrobial compound, bacteriocin. The LAB, Lacticaseibacillus paracasei F9-02 showed strong antimicrobial activity against clinical pathogens. Their proteinaceous nature was confirmed as the activity was completely abolished when treated with proteinaceous enzymes and retained during neutral pH and catalase treatment. The purified bacteriocin showed antimicrobial activity at the minimum inhibitory concentration (MIC) value of 7.56 μg/ml against vancomycin-resistant Enterococcus sp. [vancomycin-resistant enterococcal (VRE)], and methicillin-resistant Staphylococcus aureus (MRSA), 15.13 μg/ml against Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella enterica subsp. enterica serotype typhi and 30.25 μg/ml against Shigella flexneri. Present study also proved the bactericidal, non-cytotoxic and non-hemolytic nature of bacteriocin. Additionally, bacteriocin retained their stability under various physico-chemical conditions, broad range of pH (2–10), temperature (40–121°C), enzymes (amylase, lipase and lysozyme), surfactants [Tween-20, 80, 100 and sodium dodecyl sulfate (SDS)], metal ions (CaCl₂, FeSO₄, ZnSO₄, MgSO₄, MnSO₄, CuCl₂) and NaCl (2%–8%). The molecular weight of bacteriocin (~28 kDa) was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), functional and active groups were assessed by Fourier Transform-Infrared (FT-IR). To our knowledge, this is the first study reporting L. paracasei from breast-fed infants' faeces and assessing their antimicrobial compound, bacteriocin. The study results furnish the essential features to confirm the therapeutic potential of L. paracasei F9-02 bacteriocin.     

Lactobacillus paracasei subsp. paracasei 8700:2 Degrades Inulin-Type Fructans Exhibiting Different Degrees of Polymerization

Ten strains of lactobacilli were assessed for their capacity to degrade inulin-type fructans, which are well-known prebiotics. Both oligofructose and inulin were tested. The dairy isolate Lactobacillus acidophilus IBB 801 degraded only oligofructose. The human isolate Lactobacillus paracasei subsp. paracasei 8700:2 degraded oligofructose and long-chain inulin and grew rapidly on both energy sources. In both cases, fractions of different degrees of polymerization were fermented. Moreover, large and short fractions of oligofructose were degraded simultaneously. When L. paracasei subsp. paracasei 8700:2 grew on oligofructose-enriched inulin, oligofructose was preferentially metabolized. In all cases, lactic acid was the main metabolic end product. Significant amounts of acetic acid, formic acid, and ethanol were produced when long-chain inulin or oligofructose-enriched inulin was used as the sole energy source.     

Molecular Discrimination of Lactobacilli Used as Starter and Probiotic Cultures by Amplified Ribosomal DNA Restriction Analysis

Lactic acid bacteria such as Lactobacillus helveticus, L. delbrueckii subsp. delbrueckii, L. delbrueckii subsp. lactis, L. delbrueckii subsp. bulgaricus, L. acidophilus, and L. casei related taxa which are widely used as starter or probiotic cultures can be identified by amplified ribosomal DNA restriction analysis (ARDRA). The genetic discrimination of the related species belonging to these groups was first obtained by PCR amplifications by using group-specific or species-specific 16S rDNA primers. The numerical analysis of the ARDRA patterns obtained by using CfoI, HinfI, Tru9I, and ScrFI was an efficient typing tool for identification of species of the L. acidophilus and L. casei complex. ARDRA by using CfoI was a reliable method for differentiation of L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis. Finally, strains ATCC 393 and ATCC 15820 exhibited unique ARDRA patterns with CfoI and Tru9I restriction enzymes as compared with the other strains of L. casei, L. paracasei, and L. rhamnosus. Received: 30 August 2000 / Accepted: 2 October 2000     

Isolation and phenotypic characterization of Lactobacillus casei and Lactobacillus paracasei bacteriophage-resistant mutants

Aims: To isolate and characterize bacterial strains derived from Lactobacillus casei and Lactobacillus paracasei strains and resistant to phage MLC‐A. Methods and Results: Two of nine assayed strains rendered resistant mutants with recovery efficiencies of 83% (Lact. paracasei ATCC 27092) and 100% (Lact. casei ATCC 27139). DNA similarity coefficients (RAPD–PCR) confirmed that no significant genetic changes occurred while obtaining resistant mutants. Neither parent nor mutant strains spontaneously released phages. Phage‐resistant mutants were tested against phages PL‐1, J‐1, A2 and MLC‐A8. Lactobacillus casei ATCC 27092 mutants showed, overall, lower phage resistance than Lact. paracasei ATCC 27092 ones, but still higher than that of the parent strain. Lactobacillus paracasei ATCC 27092 mutants moderately adsorbed phage MLC‐A only in calcium presence, although their parent strain successfully did it with or without calcium. Adsorption rates for Lact. casei ATCC 27139 and its mutants were highly influenced by calcium. Again, phage adsorption was higher on the original strain. Conclusions: Several isolates derived from two Lact. casei and Lact. paracasei strains showed resistance to phage MLC‐A but also to other Lact. casei and Lact. paracasei phages. Significance and Impact of the Study: This study highlights isolation of spontaneous bacteriophage‐resistant mutants from Lact. casei and Lact. paracasei as a good choice for use in industrial rotation schemes.     

Synergistic Antibacterial Efficiency of Bacteriocin and Silver Nanoparticles Produced by Probiotic Lactobacillus paracasei Against Multidrug Resistant Bacteria

Contamination of wounds with multidrug-resistant microorganisms is one of the greatest challenges in the curing of many diseases, and therefore, the search for alternative antimicrobial agents becomes urgent. In the present study, out of 280 bacterial isolates recovered from 57 wound swabs of patients, 199 isolates (71.1%) showed multiple drug resistance (MDR). Staphylococcus aureus was the most predominant (80.0%), followed by Pseudomonas aeuroginosa (78.87%). A number of 121 isolates (60.80%) of MDR was sensitive to bacteriocin produced by a probiotic strain of Lactobacillus paracasei. However, considering that bacteriocins may be degraded before reaching its target, silver nanoparticles (AgNPs) can be used as a suitable candidate for combinations with bacteriocin in order to be more effective. AgNPs were synthesized using the same strain and then characterized by UV–Vis spectroscopy, TEM and XRD analyses. Bacteriocin/AgNPs bioconjugate exhibited a higher antibacterial efficiency against MDR strains than that of bacteriocin or AgNPs alone. Interestingly, the bioconjugate has significantly increased the disruption of cell membrane permeability, leakages of protein and DNA, in addition to the formation of bactericidal reactive oxygen species than any other extracts. Therefore, the combination of bacteriocin with metal nanoparticles is recommended as a promising approach for the elimination of MDR organisms.

     

In Vitro Characterization of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> Strains with Inhibitory Activity on Enteropathogens for Use as Potential Animal Probiotics

The present study evaluates the probiotic properties of three Lactobacillus plantarum strains MJM60319, MJM60298, and MJM60399 possessing antimicrobial activity against animal enteric pathogens. The three strains did not show bioamine production, mucinolytic and hemolytic activity and were susceptible to common antibiotics. The L. plantarum strains survived well in the simulated orogastrointestinal transit condition and showed adherence to Caco-2 cells in vitro. The L. plantarum strains showed strong antimicrobial activity against enterotoxigenic Escherichia coli, Shiga toxin-producing E. coli, Salmonella enterica subsp. enterica serovar Typhimurium, Choleraesuis and Gallinarum compared to the commercial probiotic strain Lactobacillus rhamnosus GG. The mechanism of antimicrobial activity of the L. plantarum strains appeared to be by the production of lactic acid. Furthermore, the L. plantarum strains tolerated freeze-drying and maintained higher viability in the presence of cryoprotectants than without cryoprotectants. Finally, the three L. plantarum strains tolerated NaCl up to 8% and maintained >60% growth. These characteristics of the three L. plantarum strains indicate that they could be applied as animal probiotic after appropriate in vivo studies.     

Mitogenic response and probiotic characteristics of lactic acid bacteria isolated from indigenously pickled vegetables and fermented beverages

Lactic acid bacteria from indigenous pickled vegetables and fermented beverages (fermented rice and Madhuca longifolia flowers) were isolated and investigated for their functional characteristics in vitro as potential new probiotic strains. Four isolates (all Lactobacillus spp.) selected on the basis of high tolerance to bile (0.2%) were identified by standard and molecular methods (16S rDNA) as L. helveticus, L. casei, L. delbrueckii and L. bulgaricus from pickled vegetables and fermented beverages respectively. These selected strains had antibiotic resistance, tolerance to artificial gastric juice and phenol (0.4%), enzymatic profile, and antagonistic activity against enteric pathogens (Enterobacter sakazakii, Salmonella typhimurium, Shigella flexneri 2a, Listeria monocytogenes, Yersinia enterocolitica and Aeromonas hydrophila). All strains survived well in artificial gastric juice at low pH (3.0) values for 4 h, possessed bile salt hydrolase activity and were susceptible to most antibiotics including vancomycin. Additionally, the isolates exhibited high tolerance to phenol, high cell surface hydrophobicity (>60%) and induced proliferation of murine splenocytes. All the four strains of present study suppressed the Con A-stimulated proliferation of the mouse spleen cells, although L. casei had the strongest suppressive effect. The results of this study suggest a potential application of the strains (following human clinical trials), for developing probiotic foods.