On the benefit of whey-cultured Lactobacillus casei in murine colitis.

The objective of this study was to examine the prophylactic and therapeutic effect of whey-cultured Lactobacillus casei (L. casei) in a murine model of colitis. Colitis was induced by intracolonic administration of a mixture of 2,4,6-trinitrobenzenesulphonic acid (TNBS)/absolute ethanol in male Wistar rats. Animals were divided into 5 groups including sham (normal group), control (vehicle-treated), positive control (dexamethasone 1 mg/kg/day, orally), prevention (10(8) cfu L. casei/day, orally, 14 days before induction of colitis), and treatment (10(8) cfu L. casei/day, orally, 14 days after induction of colitis). After 14-days treatment, the animals were sacrificed on the day 15. Distal colons were removed for examining histological and biochemical assays. Biomarkers including TNF-α, myeloperoxidase (MPO), and lipid peroxidation (LPO) were measured in the homogenate of colon. Results indicated an apparent improvement in colon histopathology scores, TNF-α, MPO, and LPO in the treatment group, whereas prevention group did not demonstrate positive efficacy in prevention of colonic damage. It is concluded that L. casei grown in whey culture is very effective in ameliorating both biochemical and histopathological markers of colitis if used post induction of colitis but not if used before induction of colitis. The difference between effects of L. casei when used pre-colitis and post-colitis confirms its mechanism of action as an anti toxic stress agent. Further studies should be made in IBD patients.

Effect of probiotication on antioxidant and antibacterial activities of pomegranate juices from sour and sweet cultivars.

There is an increasing interest in using pomegranate juice as a natural antioxidant rather than synthetic compounds. In this study, the antioxidant capacities of probioticated and nonprobioticated aril juices of sweet (SWV) and sour (SV) pomegranate cultivars were determined by two different methods: ferric reducing antioxidant power (FRAP) and 1,1-diphenyl 2-picrylhydrazyl assay. Total counts of Lactobacillus casei GG increased by about 3 log in SWV and 2 log in SV juices after incubation for 48 h. Probiotication improved the antioxidant activity of SWV juice from 74.4% to 91.82%, and SV juice from 82.64% to 97.8%. Based on the FRAP value, the reducing power of the probioticated pomegranate juices was also much stronger than the nonprobioticated juices. The FRAP values for SWV and SV probioticated juices were 97.34 and 120.7 mmol L(-1), respectively, which were notably higher than 85.87 and 93.4 mmol L(-1) for SWV and SV nonprobioticated juices. Both fermentated and nonfermentated juices exhibited a potent and wide-spectrum antibacterial effect, with the highest activity against Pseudomonas aeruginosa. SV juice showed wider zones of growth inhibition. The results of this study verify for the first time that probiotication of SWV and SV pomegranate juices can add to their beneficial antioxidant activities.

Antimicrobial activity of different Lactobacillus species against multi- drug resistant clinical isolates of Pseudomonas aeruginosa.

BACKGROUND: Lactobacilli are the well known friendly bacteria for their probiotic activities against pathogens. The inhibitory activity of different strains of lactobacilli either obtained as commercial products or isolated from human feces was investigated against the clinical isolates of Pseudomonas aeruginosa. The isolates were selected as the most resistant strains when challenged with anti-pseudomonal antibiotics already in clinical practice. MATERIALS AND METHODS: Both the plate spot test as well as the agar cup method were used for screening of Lactobacillus strains against Pseudomonas aeruginosa. RESULTS: A Lactobacillus acidophilus strain isolated from feces of an Iranian child showed a strong anti-pseudomonal activity (90 percent after 72h incubation) against the multi-drug resistant clinical isolates while a Lactobacillus reuteri strain isolated from a commercial oral product resulted in relatively weak response and a Lactobacillus acidophilus strain isolated from a commercial vaginal product did not show any inhibitory activity. In a kinetic study the lactobacillus sensitive Pseudomonas aeruginosa showed a significant bacteriostatic activity in vitro in the presence of lactobacillus supernatants. CONCLUSION: Some lactobacilli exhibit significant inhibitory activity against the multidrug resistant clinical isolates of Pseudomonas aeruginosa.

Selection for autochthonous bifidobacteial isolates adapted to simulated gastrointestinal fluid.

BACKGROUND AND THE PURPOSE OF THE STUDY: Bifidobacterial strains are excessively sensitive to acidic conditions and this can affect their living ability in the stomach and fermented foods, and as a result, restrict their use as live probiotic cultures. The aim of the present study was to obtain bifidobacterial isolates with augmented tolerance to simulated gastrointestinal condition using cross-protection method. METHODS: Individual bifidobacterial strains were treated in acidic environment and also in media containing bile salts and NaCl. Viability of the acid and acid-bile-NaCl tolerant isolates was further examined in simulated gastric and small intestine by subsequent incubation of the probiotic bacteria in the corresponding media for 120 min. Antipathogenic activities of the adapted isolates were compared with those of the original strains. RESULTS AND MAJOR CONCLUSION: The acid and acid-bile-NaCl adapted isolates showed improved viabilities significantly (p<0.05) in simulated gastric fluid compared to their parent strains. The levels of reduction in bacterial count (Log cfu/ml) of the acid and acid-bile-NaCl adapted isolates obtained in simulated gastric fluid ranged from 0.64-3.06 and 0.36-2.43 logarithmic units after 120 min of incubation. There was no significant difference between the viability of the acid-bile-NaCl-tolerant isolates and the original strains in simulated small intestinal condition except for Bifidobacterium adolescentis (p<0.05). The presence of 15 ml of supernatants of acid-bile-NaCl-adapted isolates and also those of the initial Bifidobacterium strains inhibited pathogenic bacterial growth for 24 hrs. Probiotic bacteria with improved ability to survive in harsh gastrointestinal environment could be obtained by subsequent treatment of the strains in acid, bile salts and NaCl environments.

Live and heat-inactivated lactobacilli from feces inhibit Salmonella typhi and Escherichia coli adherence to Caco-2 cells.

A quantitative approach has been proposed to evaluate the competitive inhibition of Escherichia coli and Salmonella typhi by live and heat-inactivated laboratory isolated Lactobacillus sp. on adhesion to monolayer of Caco-2 cells. Three species of Lactobacillus (L. casei, L. acidophilus, L. agilis) isolated from human neonate feces and two commercial probiotic strains (L. casei, L. acidophilus) have been compared for probiotic activity. All lactobacilli were able to attach to the Caco-2 cells, however, the degree of adhesion was bacterial strain-dependent. The adhesion indices of the two commercial probiotic strains were not significantly different from the values obtained for the other two similar fecal strains (p > 0.01). The inhibition of attachment of the pathogenic bacteria by inactivated cells of fecal L. acidophilus was examined and compared to the results of live bacteria. The inhibition pattern was similar for live and heat-inactivated L. acidophilus (p > 0.01). The number of attached pathogenic bacteria to the Caco-2 cells decreased when the number of L. acidophilus increased from 10(6) to 10(9) CFU/mL. The heat-inactivated L. acidophilus displayed similar probiotic activity compared to the live bacteria.

1-methyl malate from Berberis integerrima fruits enhances the antibacterial activity of ampicillin against Staphylococcus aureus.

The enhancement of the antibacterial activity of ampicillin by different extracts of Berberis integerrima fruits was evaluated against Staphylococcus aureus. Disk diffusion and agar dilution methods were used to determine the antibacterial activity of ampicillin in the absence and presence of different plant extracts or various fractions eluted by column chromatography. A clinical isolate of S. aureus was used as a test strain. The active component of B. integerrima fruits involved in the enhancement of ampicillin activity was purified and identified as 1-methyl malate using different spectroscopic methods. Both the ethanol extract of B. integerrima fruits and 1-methyl malate enhanced the antibacterial activity of ampicillin. The total extract as well as 1-methyl malate increased the antibacterial activity of ampicillin against the test strain. The potency of ampicillin against the test strain was increased 64-fold when tested with a sub-toxic concentration of total extract of B. integerrima fruits. Also, 1-methyl malate increased the bactericidal activity of ampicillin. In the presence of 2 mg/mL of 1-methyl malate the MIC of ampicillin for S. aureus decreased from 128 to 1 microg/mL (128-fold).

Effects of salinity on beta-carotene production by Dunaliella tertiolecta DCCBC26 isolated from the Urmia salt lake, north of Iran.

This study examined the effect of different salt concentrations (0.05-3 M of NaCl) on the kinetics of growth, total carotenoids and beta-carotene (all-trans and 9-cis) accumulated in Dunaliella tertiolecta DCCBC26, a microalgae strain isolated from the Urmia hypersaline lake, northwest of Iran. Results indicated that the highest amount of carotenoids detected (11.73 mg/l) was in the salinity of 0.5 M NaCl during the stationary growth phase. The percentage of the all-trans and 9-cis-beta-carotene in the exponential phase were 92% and 32% in salinities of 3 M and 0.5 M, respectively. However, only 23% of the beta-carotene was detected in the stationary growth phase of the microalgae in 0.5 M salinity and was 9-cis isomer.

Inhibition of nitrofurantoin reduction by menthol leads to enhanced antimicrobial activity.

Nitrofurantoin is a nitroaromatic compound used for the treatment of urinary tract infections. Nitrofurantoin activity is regulated by a nitroreduction process. It is first reduced by bacterial nitroreductases to active short-life intermediates, which are further converted to non-toxic molecules, which negatively affect its antibacterial activity. In this study we have shown that resistant strains of Klebsiella sp. inactivate the bactericidal activity of nitrofurantoin. Also we demonstrated a synergistic effect between menthol and nitrofurantoin bactericidal activities against nitrofurantoin susceptible Enterobacteriaceae.