Antimutagenicity of milk fermented by Enterococcus faecium

Combination treatment of rat adjuvant-induced arthritis with methotrexate, probiotic bacteria Enterococcus faecium, and selenium

The effects of the probiotic bacteria Enterococcus faecium (EF) and selenium were studied on methotrexate (MTX) treatment in rats with adjuvant arthritis. Arthritic rats were treated orally with the following substances: lyophilized EF (15 mg/kg/day, 5 days a week), sodium selenite pentahydrate (SSe; 0.050 mg/kg containing 0.015 mg/kg selenium, 5 days a week), MTX (0.6 mg/kg/week), and their combinations for the period of 50 days from adjuvant application. Levels of serum albumin, serum nitrite/nitrate concentrations, hind paw swelling, arthrogram scores, whole-body bone mineral density (BMD), and bone erosions were evaluated as markers of inflammation and destructive changes associated with arthritis. Long-term preventive treatment with low-dose MTX significantly inhibited the markers of both inflammation and arthritis. EF or SSe when administered singly or in combination had no significant effect on the given parameters in arthritic rats. EF, but not SSe, potentiated the beneficial effects of MTX, which resulted in a more significant reduction of hind paw swelling, arthrogram scores, and whole-body BMD decrease. EF also had a tendency to improve the effect of MTX on serum albumin and nitrite/nitrate concentrations. Our results indicate that EF may increase the preventive effect of MTX treatment in rat adjuvant arthritis by improving its anti-inflammatory and antiarthritic effects.

Synergic activity of selenium and probiotic bacterium Enterococcus faecium M-74 against selected mutagens in Salmonella assay

Concentrated extracts of MRS (De Man-Rogosa-Sharpe) media in which probiotic bacterium Enterococcus faecium strain M-74 was grown exerted different antimutagenic activity against ofloxacin-, N-methyl, N'-nitro-N-nitrosoguanidine- and sodium 5-nitro-2-furylacrylate-induced mutagenicity in Salmonella typhimurium assay depending on the presence (+Se) or absence of disodium selenite pentahydrate (-Se). The antimutagenicity of MRS(+Se) extract was higher than that of MRS(-Se) extract. Selenium enhanced also the antimutagenic effect of both live and killed cells of E. faecium M-74, respectively. The live bacteria decreased the mutagenicity of selected substances more than killed cells. Synergic activity of selenium with the bacterium was also manifested.

Evidence for chromosomal determination of fungicidal activity in strains of Lactobacillus brevis and Lactobacillus fermentum isolated from fermented foods

The genetic basis of the fungicidal activity of strains of Lactobacillus brevis and L. fermentum isolated from indigenous fermented foods was determined. A 5.5-kb plasmid was isolated from L. brevis while L. Fermentum was found to harbor no plasmid. Plasmid curing indicated no correlation between the plasmid and the fungicidal activity of the Lactobacillus species. The fungicidal activity of the isolated organisms can be supposed to be mediated by the chromosome. No antibiotic resistance genetic markers were detected on the plasmid and hence it was classified as cryptic.

Phenolic acids reduce the genotoxicity of acridine orange and ofloxacin in Salmonella typhimurium

Naturally occurring plant phenolics, p-coumaric acid (PA), caffeic acid (CA), ferulic acid (FA) and gentisic acid (GA) (25-100 nmol/L) had protective effects on acridine orange (AO; 216 mumol/L)- and ofloxacin (3 mumol/L)-induced genotoxicity in Salmonella typhimurium. FA, GA and CA exhibited a significant concentration-dependent protective effect against the genotoxicity of AO and ofloxacin, with the exception of PA, which at all concentrations tested abolished the AO and ofloxacin genotoxicity. UV spectrophotometric measurements showed the interaction of PA, FA, GA and CA with AO but not with ofloxacin; this interaction is obviously responsible for the reduction of AO-induced S. typhimurium mutagenicity. In the case of ofloxacin the antimutagenic effect of PA, FA, GA and CA is assumed to be a result of their ability to scavenge reactive oxygen species (ROS) produced by ofloxacin.

Isolation and partial characterization of an antibacterial substance produced by Enterococcus faecium

A strain of Enterococcus faecium isolated from Bulgarian yellow cheese "kashkaval" produced a bacteriocin-like substance named enterococcin A 2000. The antibacterial substance had a low molar mass (< 2 kDa), was relatively stable toward heat but was sensitive to selected proteolytic enzymes. It was active against Gram-positive bacteria including enterococci, such as Listeria, Bacillus and Streptococcus, and also against Gram-negative E. coli. Production of enterococcin A 2000 has a maximum near the end of the exponential phase of producer growth. The peptide was purified by ammonium sulfate precipitation, butanol extraction, followed by cation-exchange chromatography and reversed-phase chromatography. A partial sequence of purified enterococcin A 2000 indicated that this substance does not belong to the class IIa of bacteriocins presenting the consensus anti-Listeria motif YGNGV.

Treatment of experimental adjuvant arthritis with the combination of methotrexate and lyophilized Enterococcus faecium enriched with organic selenium

The efficacy of combination therapy with methotrexate (MTX) and probiotic bacteria Enterococcus faecium enriched with organic selenium (EFSe) in rats with adjuvant arthritis was determined. Rats with adjuvant arthritis were given MTX (0.3 mg/kg 2-times weekly, orally); lyophilized E. faecium enriched with Se (15 mg/kg, 5 d per week, orally); and a combination of MTX plus EFSe for a period of 50 d from the immunization. Levels of serum albumin, serum nitrite/nitrate concentrations, changes in hind paw swelling, arthrogram score, bone erosions, whole body bone mineral density (BMD) and bone mineral content (BMC) were assayed in the rats as variables of inflammation and destructive arthritis-associated changes. Treatment with MTX and with the combination MTX + EFSe significantly inhibited markers of both inflammation and arthritis. Significant differences in favor of combination therapy with MTX + EFSe as compared to MTX alone were seen in serum albumin concentration, hind paw swelling and arthrogram score. Reductions in radiographic scores were also more pronounced in the combination therapy group. Combination therapy, but not MTX alone, inhibited the reduction of BMD and BMC; treatment with lyophilized EFSe alone had no significant effect on adjuvant arthritis in rats. The potent therapeutic effect of low dosage MTX therapy in combination with lyophilized EFSe on adjuvant arthritis in rats was shown.

PCR-based methods for identification of Enterococcus species

Two DNA-based techniques were used for species identification of enterococci. PvuII digestion of the genus-specific PCR product yielded four different restriction profiles among 20 enterococcal species; one of them was species-specific for E. faecium. In the second case, 32 reference strains belonging to 20 enterococcal species were divided to 12 groups by amplification of internal transcribed spacer of rRNA operon. Interspecies and some intraspecies profile variability was determined. Both methods gave similar results.

Effects of nitrogen sources on bacteriocin production by Enterococcus faecium A 2000

The production of a novel broad-spectrum antimicrobial peptide enterococcin A 2000, active against Gram-positive and Gram-negative microorganisms including Listeria subsp. and Escherichia coli, by Enterococcus faecium strain A 2000 isolated from the surface of traditional Bulgarian yellow cheese "kash-kaval" is considerably influenced by complex nitrogen sources in the production medium. Medium components, especially peptone and yeast extract, and their concentration contributed to the increase in bacteriocin production during the stationary phase (16-46 h) of cultivation even in the absence of one of the components present in the basal cultivation MRS medium.

Verification of hypocholesterolemic effect of fermented milk on human subjects with different cholesterol levels

The possible hypocholesterolemic effect of acidophilus milk was evaluated on 27 human subjects having different levels of serum cholesterol, i.e. < 2.0 (group C1), 2.0-2.2 (C2), 2.2-2.5 (C3) and > 2.5 g/L (C4). The acidophilus milk was prepared by fermentation of low-fat milk with Lactobacillus acidophilus and was fed to each volunteer at the rate of 200 mL/d for 20 d. Blood samples from the volunteers were collected and analyzed for lipid profile twice prior to, during and after feeding, keeping a gap of 10 d between two collections. A significant decrease (p < 0.05) in average total cholesterol was found in the C2 and C3 groups, amounting to 21 and 12%, respectively. The average LDL cholesterol decreased in C2, C3 and C4 groups by 0.54, 0.26 and 0.46 g/L, respectively. In the C2 group, the LDL/HDL and total/HDL ratio was also reduced by 1.4 and 1.3, respectively. However, in the C1 group, the average total and LDL cholesterol level did not show any significant change but serum triacylglycerols and VLDL cholesterol showed a significant (p < 0.05) increase of 0.53 and 0.11 g/L, respectively. Regression analysis of the data revealed a square trend in most of the parameters over time period. Overall, the feeding had the best effect in the subjects with lipidemic status of borderline cholesterol level (2.0-2.2 g/L) group.

Anti-staphylococcal effect of enterocin in Sunar and yogurt

Enterocin was used to control the growth of Staphylococcus aureus strains SA1 and Oxford 209P in Sunar (milk nourishment for suckling babies) and during the yogurt-making process. Reduction by three orders of magnitude was noted in the growth of SA1 strain in Sunar milk nourishment between the enterocin-containing (ES) and the control samples (CS) at 1-d cultivation. An inhibitory effect of enterocin was observed when surviving of SA1 cells were checked 6 h after the start of cultivation (2 h after enterocin application; enterocin was applied after 4 h). Decrease in the count of Oxford 209P strain in yogurt was detected in ES after 1 d of storage in comparison with CS (10(3) and 10(0) CFU mL-1 g-1). Thus a decrease by three orders of magnitude was found between ES and CS at the time mentioned. On the other hand, no bacteriocin activity was detected in ES after 1 d. Activity was detected only immediately after enterocin addition to ES (400 AU/mL) as well as after 1 and 3 1/2 h (200 AU/mL). Although the slight regrowth of the indicator was obtained up to 1 week of yogurt storage, the difference between ES and CS persisted. The lowest pH of the final yogurt product was noted in the reference yogurt sample but differences among the pH values of yogurt samples were not significant.