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PubMed1996

Structural characterization of the exopolysaccharide produced by Lactobacillus acidophilus LMG9433.

The exopolysaccharide produced by Lactobacillus acidophilus LMG9433 in a semi-defined medium was found to be a charged heteropolymer, with a composition of D-glucose, D-galactose, D-glucuronic acid, and 2-acetamido-2-deoxy-D-glucose in molar ratios of 2:1:1:1. By means of methylation analysis, uronic acid degradation, de-N-acetylation/deamination, partial acid hydrolysis, and 1D/2D NMR studies the polysaccharide was demonstrated to consist of repeating units with the following structure: [Table: see text]

Carbohydrate Conformation↗
PubMed1997

Inhibition of initial adhesion of uropathogenic Enterococcus faecalis to solid substrata by an adsorbed biosurfactant layer from Lactobacillus acidophilus.

OBJECTIVES: The potency of the Lactobacillus acidophilus RC14 biosurfactant "surlactin" to reduce the initial adhesion of Enterococcus faecalis 1131 was investigated on a hydrophilic and a hydrophobic substratum in a parallel-plate flow chamber, using phosphate-buffered saline and pooled human urine as a suspending fluid. METHODS: A parallel-plate flow chamber with a glass or silicone rubber bottom plate was filled with different biosurfactant solutions of 0, 0.01, 0.1, or 1.0 mg/mL for overnight adsorption (18 hours). Subsequently, the adhesion of E. faecalis on thus prepared biosurfactant layers was observed in situ in phosphate-buffered saline or in urine by automated image analysis. RESULTS: Adsorbed biosurfactant layers caused an important, dose-related inhibition of the initial deposition rate of E. faecalis and the number of adherent bacteria after 4 hours on both hydrophilic glass and hydrophobic silicone rubber, although this effect was stronger in buffer than in urine. For the experiments carried out in urine, the inhibitory effect of the biosurfactant layer was largest when silicone rubber was used rather than glass, whereas no influence of the substratum hydrophobicity on the inhibition of E. faecalis adhesion was noticed for experiments performed in buffer. CONCLUSIONS: The biosurfactant surlactin, as released by several Lactobacillus isolates, might open the way to the development of antiadhesive biologic coatings for catheter materials. It should be considered, however, that these results are preliminary and that the efficiency of the biosurfactant is probably affected not only by the hydrophobicity of the substratum and the suspending fluid, but also by the type of uropathogen involved.

Bacterial Adhesion↗
PubMed1994

Evidence for the presence of plasmids in four therapeutically important strains of Lactobacillus acidophilus.

Four therapeutically important strains of Lactobacillus acidophilus designated as R, 301, 1899 and NCFM were screened for the presence of plasmids. Two lysis methods were used for the isolation of plasmid DNA: an alkaline method and a more gentle technique. It was found that the gentle lysis method yielded better plasmid DNA both quantitatively and qualitatively. All four strains studied apparently possess plasmids. The strains 301 and NCFM possessed one plasmid each, with a size of 4.2 kb, whereas R possessed three plasmids (3.5, 2.4 and 2.1 kb) and 1899 possessed two plasmids (4.1 and 4.2 kb). Restriction analysis revealed that the plasmid DNA from strain R was cleaved by Bam HI but not by Hind III and Eco RI. The plasmid DNA from the remaining three strains was cleaved by all three restriction enzymes used.

DNA, Bacterial↗
PubMed2001

Invited review: the scientific basis of Lactobacillus acidophilus NCFM functionality as a probiotic.

Lactobacillus acidophilus NCFM is a probiotic strain available in conventional foods (milk, yogurt, and toddler formula) and dietary supplements. Its commercial availability in the United States since the mid-1970s is predicated on its safety, its amenability to commercial manipulation, and its biochemical and physiological attributes presumed to be important to human probiotic functionality. The strain has been characterized in vitro, in animal studies, and in humans. NCFM is the progenitor of the strain being used for complete chromosome sequencing and therefore will be a cornerstone strain for understanding the relationship between genetics and probiotic functionality. Both phenotypic and genotypic techniques have verified its taxonomic status as a type A1 L. acidophilus strain. It adheres to Caco-2 and mucus-secreting HT-29 cell culture systems, produces antimicrobial compounds, and is amenable to genetic manipulation and directed DNA introduction. NCFM survives gastrointestinal tract transit in both healthy and diseased populations. NCFM inhibits aberrant crypt formation in mutagenized rats, indicative of activity that could decrease the risk of colon cancer. A blend of probiotic strains containing NCFM decreased the incidence of pediatric diarrhea. NCFM led to a significant decrease in levels of toxic amines in the blood of dialysis patients with small bowel bacterial overgrowth. At adequate daily feeding levels, NCFM may facilitate lactose digestion in lactose-intolerant subjects. Further validation of the probiotic properties of NCFM in humans and clarification of its mechanisms of probiotic action are needed to better understand the role this strain might play in promoting human health.

Anticarcinogenic Agents↗
PubMed1998

Interference in initial adhesion of uropathogenic bacteria and yeasts to silicone rubber by a Lactobacillus acidophilus biosurfactant.

The ability of the Lactobacillus acidophilus RC14 biosurfactant 'surlactin' to inhibit the initial adhesion of various uropathogenic bacteria and two yeast strains to silicone rubber was investigated in a parallel-plate flow chamber in filter-sterilised pooled human urine. A parallel-plate flow chamber with a silicone rubber bottom plate was filled with a 1.0 mg/ml biosurfactant solution for adsorption overnight (18 h). Subsequently, the adhesion of the bacterial or yeast cells from a urine suspension under low flow (shear rate 15 s(-1)) was followed in situ by automated image analysis. Control tests were with untreated silicone rubber. Initial deposition rates and numbers of adhering cells after 4 h of flow were determined. Surlactin layers caused a marked inhibition of the initial deposition rates and adhesion numbers after 4 h for the majority of the bacteria (11 of 15 strains tested) and this inhibition was particularly effective against Enterococcus faecalis, Escherichia coli and Staphylococcus epidermidis. Although the initial deposition rates of the two Candida albicans strains were reduced by c. 50% in comparison with the controls, the numbers of yeast cells adhering after 4 h were similar.

Adult↗
PubMed1992

Ingestion of yogurt containing Lactobacillus acidophilus as prophylaxis for candidal vaginitis.

OBJECTIVE: To assess whether daily ingestion of yogurt containing Lactobacillus acidophilus prevents vulvovaginal candidal infections. DESIGN: Crossover trial for at least 1 year during which patients were examined for candidal infections and colonizations while receiving either a yogurt-free or a yogurt-containing diet. Patients served as their own controls. SETTING: Ambulatory infectious disease center in a teaching hospital providing tertiary care. PATIENTS: Thirty-three women with recurrent candidal vaginitis were eligible after recruitment from community practices and clinics and through advertising. Twelve patients were eliminated for protocol violations. Of the remaining 21 patients, 8 who were assigned to the yogurt arm initially refused to enter the control phase 6 months later. Thus, 13 patients completed the protocol. INTERVENTIONS: Women ate yogurt for 6 months of the study period. MEASUREMENTS: Colonization of lactobacilli and candida in the vagina and rectum; candidal infections of the vagina. MAIN RESULTS: Thirty-three eligible patients were studied. A threefold decrease in infections was seen when patients consumed yogurt containing Lactobacillus acidophilus. The mean (+/- SD) number of infections per 6 months was 2.54 +/- 1.66 in the control arm and 0.38 +/- 0.51 per 6 months in the yogurt arm (P = 0.001). Candidal colonization decreased from a mean of 3.23 +/- 2.17 per 6 months in the control arm to 0.84 +/- 0.90 per 6 months in the yogurt arm (P = 0.001). CONCLUSION: Daily ingestion of 8 ounces of yogurt containing Lactobacillus acidophilus decreased both candidal colonization and infection.

Adult↗
PubMed1999

Yoghurt enriched with Lactobacillus acidophilus does not lower blood lipids in healthy men and women with normal to borderline high serum cholesterol levels.

OBJECTIVE: To investigate whether intake of Lactobacillus acidophilus strain L-1 lowers serum cholesterol in healthy men and women. DESIGN: Randomised, placebo-controlled parallel trial. SETTING: Subjects were free-living. Blood sampling and distribution of yoghurts were administered at a local hospital. SUBJECTS: Seventy-eight adult men and women with cholesterol levels of 3.9-7.8 mmol/L (mean +/- s.d., 5.4+/-0.7). INTERVENTIONS: Subjects consumed 500 mL of control yoghurt daily for two weeks. They were then randomly allocated to receive 500 mL per day of control yoghurt or of yoghurt enriched with Lactobacillus acidophilus L-1 for another six weeks. The yoghurts were spiked with a trace of lithium; compliance as assessed by plasma lithium was excellent. RESULTS: Energy and nutrient intake was constant, and identical for the two groups. Mean body weight was stable. Baseline blood lipid concentrations in the control and treatment groups were highly similar. The effect of consumption of Lactobacillus acidophilus L-1 vs. control on total cholesterol was -0.02 mmol/L (95% CI, -0.18-0.15) after three weeks and 0.04 mmol/L (95% CI, -0.12-0.20) after six weeks. Serum LDL and HDL-cholesterol and triacylglycerol levels were also unaffected. CONCLUSIONS: Yoghurt enriched with Lactobacillus acidophilus L-1 does not lower serum cholesterol in men and women with normal to borderline high cholesterol levels.

Adolescent↗
PubMed1992

Interferon induction in murine peritoneal macrophage by stimulation with Lactobacillus acidophilus.

Induction of interferon for a kind of dairy lactic acid bacteria, Lactobacillus acidophilus (L. acidophilus), was investigated in murine peritoneal macrophage (M phi) cultures. Lactobacillus acidophilus JCM 1034, 1132T, 1229 and 2125 induced IFN (12-34 I.U./ml) in M phi cultures in vitro. Strain 1132T- and 2125-induced IFNs were characterized as IFN alpha/beta by treatment with anti-IFNs serum. The results indicate that the inducing activity of IFNs may be one of the available biological parameters for designating the dairy products containing L. acidophilus as "physiologically functional foods."

Animals↗
PubMed2005

Importance of S-layer proteins in probiotic activity of Lactobacillus acidophilus M92.

AIMS: To investigate the functional role of surface layer proteins (S-layer) in probiotic strain Lactobacillus acidophilus M92, especially its influence on adhesiveness to mouse ileal epithelial cells. METHODS AND RESULTS: Sodium dodecyl sulphate polyacrylamide gel electrophoresis of cell surface proteins revealed the presence of potential surface layer (S-layer) proteins, ca at 45 kDa in L. acidophilus M92. Southern blot with pBK1 plasmid, containing slpA gene, gave a positive signal, suggesting that L. acidophilus M92 has a slpA gene coding for the S-layer proteins. S-layer proteins of this strain are present during all phases of growth. The S-layer proteins appeared when cells treated with 5 mol l(-1) LiCl were allowed to grow again. Removal of the S-layer proteins reduced adhesion of L. acidophilus M92 to mouse ileal epithelial cells. Furthermore, the viability of cells without S-layer were reduced in simulated gastric juice at low pH range (2, 2.5, 3) and simulated pancreatic juice with bile salts (1.5 and 3 g l(-1)). S-layer proteins of L. acidophilus M92 were resistant to pepsin and pancreatin, in contrast, the treatment with proteinase K led to a significant proteolysis of the S-layer proteins. CONCLUSIONS: These results demonstrated functional role of S-layer; it is responsible for adhesiveness of Lactobacillus acidophilus M92 to mouse ileal epithelial cells and has a protective role for this strain. SIGNIFICANCE AND IMPACT OF THE STUDY: S-layer proteins have an important role in the establishment of probiotic strain Lactobacillus acidophilus M92 in the gastrointestinal tract.

Animals↗
PubMed1983

Detection and activity of lactacin B, a bacteriocin produced by Lactobacillus acidophilus.

A total of 52 strains of Lactobacillus acidophilus were examined for production of bacteriocins. A majority (63%) demonstrated inhibitory activity against all members of a four-species grouping of Lactobacillus leichmannii, Lactobacillus bulgaricus, Lactobacillus helveticus, and Lactobacillus lactis. Four L. acidophilus strains with this activity also inhibited Streptococcus faecalis and Lactobacillus fermentum, suggesting a second system of antagonism. Under conditions eliminating the effects of organic acids and hydrogen peroxide, no inhibition of other gram-positive or -negative genera was demonstrated by L. acidophilus. The agent produced by L. acidophilus N2 and responsible for inhibition of L. leichmannii, L. bulgaricus, L. helveticus, and L. lactis was investigated. Ultrafiltration studies indicated a molecular weight of approximately 100,000 for the crude inhibitor. The agent was sensitive to proteolytic enzymes and retained full activity after 60 min at 100 degrees C (pH 5). Activity against sensitive cells was bactericidal but not bacteriolytic. These characteristics identified the inhibitory agent as a bacteriocin, designated lactacin B. Examination of strains of L. acidophilus within the six homology groupings of Johnson et al. (Int. J. Syst. Bacteriol. 30:53-68, 1980) demonstrated that production of the bacteriocin lactacin B could not be used in classification of neotype L. acidophilus strains. However, the usefulness of employing sensitivity to lactacin B in classification of dairy lactobacilli is suggested.

Adsorption↗
PubMed1984

Importance of bile tolerance of Lactobacillus acidophilus used as a dietary adjunct.

Cultures of lactobacilli identified as Lactobacillus acidophilus from the intestinal contents of young calves varied in their ability to grow in broth containing .3% oxgall compared with control broth. Frozen concentrated cultures were prepared from a strain exhibiting low tolerance to bile and from a strain exhibiting high tolerance to bile. Plate counts were comparable from the concentrated cultures before and after frozen storage on lactobacilli MRS agar with and without .15% oxgall. In a feeding trial involving newborn dairy calves supplementation of the diet with the more bile resistant strain of Lactobacillus acidophilus caused greater increases of numbers of facultative lactobabilli in the upper small intestines than did the strain exhibiting lower resistance to bile. It was not possible to determine whether the lactobacilli would prevent intestinal infections in the calves challenged with enteropathogenic Escherichia coli. This portion of the study failed as the challenge with Escherichia coli did not cause infections even in control animals.

Animal Feed↗
PubMed1980

Effect of diet and Lactobacillus acidophilus supplements on human fecal bacterial enzymes.

The effect of diet and Lactobacillus acidophilus supplements on fecal microflora enzyme activity was studied in humans. The bacterial enzymes that were investigated are known to catalyze reactions that may result in formation of proximal carcinogens. Compared to vegetarians, omnivores eating a "Western-type" diet had higher levels of beta-glucuronidase, nitroreductase, azoreductase, and steroid 7-alpha-dehydroxylase in their fecal microflora. Removal of red meat or addition of fiber in the form of bran or wheat germ to the diet of omnivores for 30 days had no effect on beta-glucuronidase, nitroreductase, or azoreductase activity. However, removal of red meat or addition of fiber reduced fecal steroid 7-alpha-dehydroxylase activity. The addition of viable Lactobacillus acidophilus supplements to the diet of omnivores significantly decreased fecal bacterial beta-glucuronidase and nitroreductase activities. Thirty days after Lactobacillus supplements were curtailed, fecal enzyme levels returned to normal base-line activities. These findings suggested that the metabolic activity of the fecal microflora was influenced by diet and could be altered by Lactobacillus supplements and to a lesser extent by dietary fiber.

Adult↗
PubMed1988

Bacteriocin involved in premature death of Lactobacillus acidophilus NCFM during growth at pH 6.

Lactobacillus acidophilus NCFM maintained at pH 6 during growth in lactobacilli MRS broth appeared to exhibit premature death. However, during extended incubation, the culture reinitiated growth. Spent broth collected from the culture when it began the premature death was very toxic to the culture, but growth did occur during extended incubation of the assay tubes. When several successive subcultures with extended incubation were made in MRS broth containing added inhibitory spent broth, a strain (identified as L. acidophilus) was isolated that was resistant to the inhibitor. This strain produced a bacteriocin that was inhibitory to the growth of L. acidophilus NCFM and the predominating strains isolated from it. The producer strain grew more slowly than did the predominating strains in culture NCFM. The results show that when L. acidophilus NCFM, a mixed strain culture, was grown at pH 6, the inhibitory strain was able to grow sufficiently to produce enough bacteriocin to destroy the predominating strain(s) in the culture.

Bacteriocins↗
PubMed2001

Assessment of stress response of the probiotic Lactobacillus acidophilus.

Different aspects of stress response of Lactobacillus acidophilus were investigated. First, the sublethal and lethal levels of bile, heat, and NaCl stresses were determined. They were 0.05% and 0.5% (bile), 53 degrees C and 60 degrees C (heat), and 2% and 18% (NaCl), respectively. To evaluate the effect of each stress at log phase, log-phase cultures were challenged directly with the lethal level of each stress (control) and were compared to log-phase cultures that were pre-exposed to the sublethal level prior to the exposure at the lethal level (test). Some, if not most, of the cells were killed in the control cultures against each of the three stresses. However, in the test cultures, the number of cells that had survived increased significantly. It appears that L. acidophilus is capable of displaying adaptive response to stress. The adaptive response to one stress was also shown to provide cross-protection against different stresses tested. The effect of each stress on stationary-phase cultures was also investigated. In contrast to log-phase culture, stationary-phase culture was inherently resistant to stress.

Bile↗
PubMed2006

Casein-derived antimicrobial peptides generated by Lactobacillus acidophilus DPC6026.

Three peptides produced by a Lactobacillus acidophilus DPC6026 fermentation of sodium caseinate and showing antibacterial activity against pathogenic strains Enterobacter sakazakii ATCC 12868 and Escherichia coli DPC5063 were characterized. These peptides were all generated from bovine alpha(s1)-casein and identified as IKHQGLPQE, VLNENLLR, and SDIPNPIGSENSEK. These peptides may have bioprotective applicability and potential use in milk-based formula, which has been linked to E. sakazakii infection in neonates.

Amino Acid Sequence↗
PubMed1996

Antagonistic activity of Lactobacillus acidophilus fermented milk against different pathogenic bacteria.

Lactobacillus acidophilus strains tested showed inhibitory activity towards Salmonella typhi, Staphylococcus aureus, Escherichia coli, Proteus vulgaris and Yersinia enterocolitica. However, wide variations in the activity of the strains were observed. Antagonistic activity of the strains exhibited high heat stability (120 min at 92 degrees C, 15 min at 121 degrees C) but it was markedly influenced by changes in pH. Effect of kind of milk on antagonistic activity was variable, whereas skimming had no significant effect.

Animals↗
PubMed2000

Molecular analysis of mutated Lactobacillus acidophilus promoter-like sequence P15.

The promoter-like sequence P15 that was previously cloned from the chromosome of Lactobacillus acidophilus ATCC 4356 is active in Lactobacillus reuteri, Lactobacillus plantarum, Lactobacillus acidophilus, and Escherichia coli, but not in Lactococcus lactis. N-methyl-N-nitroso-N-guanidine (MNNG) mutagenesis of P15 was used to select for a promoter active in L. lactis MG1363. Molecular analysis of the mutated promoter (designated P16) revealed a 90 bp deletion and a T-->A transversion. This deletion, in combination with the addition to the transversion, created a promoter with putative -35 and -10 hexamers identical to the consensus promoter sequence found in E. coli and Bacillus subtilis vegetative promoters. The activity of P16 was measured by its ability to promote chloramphenicol resistance in different bacteria when inserted in the promoter-probe plasmid pBV5030 (designated pLA16). The MIC of chloramphenicol in L. lactis, L. reuteri, L. plantarum, E. coli, and L. acidophilus harbouring pLA16 were 30, 170, 180, > 500, and 3 micrograms/mL, respectively. This represents an increase in promoter activity compared to P15 in L. reuteri of 3-fold, in L. plantarum of 9-fold, and in E. coli of at least 2.5-fold, but a decrease in L. acidophilus of 7-fold.

Anti-Bacterial Agents↗