Acidophilus Strain Research Articles

Inhibitory Effect of Metabolites from Probiotics Lactobacillus acidophilus Strains on Growth of Pathogenic Bacteria

Inhibitory Effect of Metabolites from Probiotics Lactobacillus acidophilus Strains on Growth of Pathogenic Bacteria

Use of the checkerboard DNA–DNA hybridisation technique for in vivo detection of cariogenic microorganisms on metallic brackets, with or without use of an antimicrobial agent

ObjectiveUsing checkerboard DNA–DNA hybridisation (CDDH) assay, this randomised clinical study evaluated the contamination of metallic brackets by four cariogenic bacterial strains (Streptococcus mutans, Streptococcus sobrinus, Lactobacillus casei and Lactobacillus acidophilus) and the efficacy of 0.12% chlorhexidine gluconate (CHX) mouthwashes in reducing bacterial contamination. MethodsThirty-nine 11–33-year-old patients under treatment with fixed orthodontic appliances were enrolled in the study and had 2 new metallic brackets bonded to premolars. Nineteen patients used a 0.12% CHX mouthwash (Periogard®) and 20 patients used a placebo mouthwash (control) twice a week. After 30 days, the brackets were removed and samples were obtained for analysis by CDDH. Data were analysed statistically by the Kruskal–Wallis test (α=0.05) using the SAS software. ResultsS. mutans, S. sobrinus, L. casei and L. acidophilus were detected in 100% of the samples from both groups. However, brackets of the control group were more heavily contaminated by S. mutans and S. sobrinus (P<0.01). In the experimental group, although all counts decreased after rinsing with the chlorhexidine solution, there was significant difference only for S. mutans (P=0.03). ConclusionsThe use of 0.12% chlorhexidine gluconate mouthwashes can be useful in clinical practice to reduce the levels of cariogenic microorganisms in patients under treatment with fixed orthodontic appliances.

Survival of probiotic adjunct cultures in cheese and challenges in their enumeration using selective media

Various selective media for enumerating probiotic and cheese cultures were screened, with 6 media then used to study survival of probiotic bacteria in full-fat and low-fat Cheddar cheese. Commercial strains of Lactobacillus acidophilus, Lactobacillus casei, Lactobacillus paracasei, or Bifidobacterium lactis were added as probiotic adjuncts. The selective media, designed to promote growth of certain lactic acid bacteria (LAB) over others or to differentiate between LAB, were used to detect individual LAB types during cheese storage. Commercial strains of Lactococcus, Lactobacillus, and Bifidobacterium spp. were initially screened on the 6 selective media along with nonstarter LAB (NSLAB) isolates. The microbial flora of the cheeses was analyzed during 9 mo of storage at 6°C. Many NSLAB were able to grow on media presumed selective for Lactococcus, Bifidobacterium spp., or Lb. acidophilus, which became apparent after 90 d of cheese storage, Between 90 and 120 d of storage, bacterial counts changed on media selective for Bifidobacterium spp., suggesting growth of NSLAB. Appearance of NSLAB on Lb. casei selective media [de man, Rogosa, and Sharpe (MRS)+vancomycin] occurred sooner (30 d) in low-fat cheese than in full-fat control cheeses. Differentiation between NSLAB and Lactococcus was achieved by counting after 18 to 24h when the NSLAB colonies were only pinpoint in size. Growth of NSLAB on the various selective media during aging means that probiotic adjunct cultures added during cheesemaking can only be enumerated with confidence on selective media for up to 3 or 4 mo. After this time, growth of NSLAB obfuscates enumeration of probiotic adjuncts. When adjunct Lb. casei or Lb. paracasei cultures are added during cheesemaking, they appear to remain at high numbers for a long time (9 mo) when counted on MRS+vancomycin medium, but a reasonable probability exists that they have been overtaken by NSLAB, which also grow readily on this medium. Enumeration using multiple selective media can provide insight into whether it is the actual adjunct culture or a NSLAB strain that is being enumerated.

LACTOBACILLUS ACIDOPHILUS DECREASES SALMONELLA TYPHIMURIUM INVASION IN VIVO

ABSTRACTThe use of probiotics has been suggested to strengthen the non‐immunological anti‐infective defenses of the gastrointestinal tract. Enteropathogenic bacterial species are common infectious agents in underdeveloped countries. Among these bacteria, Salmonella enterica, the etiological agent of salmonellosis, is considered to be an important agent of diarrheal and systemic disease. In this work, attenuated Salmonella enterica serovar Typhimurium was tested with BALB/c mice treated with Lactobacillus acidophilus strain ATCC 314. A capability of Lactobacillus adhesion to in vitro cultured cells and a significant decrease in the colony‐forming units of Salmonella in the Peyer's patches and spleen of lactobacilli‐treated mice demonstrated that Lactobacillus interferes with the adhesion, invasion and dissemination processes caused by Salmonella in this murine model, suggesting that the Lactobacillus strain could act as a probiotic agent attenuating the severity of salmonellosis. This work may contribute to studies involving probiotics on the prevention of Salmonella infections.PRACTICAL APPLICATIONSThe data indicate that lactobacilli strains may be an alternative prevention against Salmonella infections by contaminated foods. The competitive adhesion and exclusion of a probiotic strain with a pathogen are involved processes in the action of the probiotics in the combat of the intestinal infections. Our results showed that lactobacilli decreased the number of invaders salmonella bacteria in vivo. The action of probiotics using lactobacilli showed beneficial effect on infection of mice by Salmonella. These results contribute for the studies involving probiotics' activities and pathogenicity of enteric diseases.

Effects of addition of bacterial inoculants to the diets of lactating dairy cows on feed intake, milk yield, and milk composition

Forty-eight lactating Holstein cows (38 multiparous, 10 primiparous) were used in a 10-wk randomized block trial to determine the effect of 2 supplemental bacterial inoculants on DMI, milk yield, and milk composition. Experimental diets were top dressed with ground corn plus one of 2 bacterial inoculant mixtures. Treatments were control (no bacterial inoculant); 2 × 109 cfu/d of Propionibac-terium freudenreichii strain NP24 plus 1 × 109 cfu/d of Lactobacillus acidophilus strain NP51 (B1); and 2 × 109 cfu/d of P. freudenreichii strain NP24 plus 5 × 108 cfu/d each of L. acidophilus strain NP51 and strain NP45 (B2). Cows fed bacterial inoculants had greater yields of milk fat (P = 0.02), FCM (P = 0.007), and energy-corrected milk (P = 0.03) than did controls. Efficiency of milk production (defined as energy-corrected milk yield per unit of DMI) was greater (P = 0.03) for cows fed bacterial inoculants compared with control cows. There was no effect of treatment on DMI, milk fat percentage, or milk protein yield or percentage. There was a tendency (P = 0.08) for increased milk yield with inoculant supplementation compared with the control treatment. Serum urea N concentrations were greater for control cows compared with those receiving inoculants, and there was a tendency for B2 cows to have greater serum urea N concentrations compared with B1 cows. Results of this trial suggest that supplemental bacterial inoculants containing P. freudenreichii and L. acidophilus can improve milk yield and apparent efficiency of nutrient utilization.

Lipoteichoic Acid-Deficient Lactobacillus Acidophilus Regulates Downstream Signals

The trillions of microbes residing within the intestine induce critical signals that either regulate or stimulate host immunity via their bacterial products. To better understand the immune regulation elicited by lipoteichoic acid (LTA)-deficient Lactobacillus acidophilus NCFM in steady state and induced inflammation, we deleted phosphoglycerol transferase gene, which synthesizes LTA in L. acidophilus NCFM. In vitro and in vivo experiments were conducted in order to compare the immune regulatory properties of the L. acidophilus strain deficient in LTA (NCK2025) with its wild-type parent (NCK56) in C57BL/6, C57BL/6 recombination-activation gene 1-deficient (Rag1 (-/-)) and C57BL/6 Rag1(-/-)IL-10(-/-) mice. We demonstrate that NCK2025 significantly activates the phosphorylation of Erk1/2 but downregulates the phosphorylation of Akt1, cytosolic group IV PLA2 and p38 in mouse dendritic cells. Similarly, mice treated orally with NCK2025 exhibit decreased phosphorylation of inflammatory signals (Akt1, cytosolic group IV PLA2 or P38) but upregulate Erk1/2-phosphorylation in colonic epithelial cells in comparison with mice treated with NCK56. In addition, regulation of pathogenic CD4+ T cell induced colitis by NCK2025 was observed in Rag1 (-/-) but not Rag1(-/-)IL-10 (-/-) mice suggests a critical role of IL-10 that may be tightly regulated by Erk1/2 signaling. These data highlight the immunosuppressive properties of NCK2025 to deliver regulatory signals in innate cells, which results in the mitigation of T-cell-induced colitis in vivo.

The effect of a probiotic strain (Lactobacillus acidophilus) on the plaque formation of oral Streptococci

The objective of this study was to investigate the ability of biofilm formation among mutans and non mutans oral streptococci and to determine the effect of Lactobacillus acidophilus DSM 20079 as a probiotic strain on the adhesion of selected streptococcal strains on the surfaces. The sample comprised 40 isolates of oral streptococci from dental plaque and caries of volunteer persons. Streptococcus mutans ATCC35668 (no24) was as an standard strain. The probiotic strain was Lactobacillus acidophilus DSM 20079. The ability of biofilm formation was investigated with colorimetric method and the strongest isolates were selected. Then the effect of probiotic strain on the adhesion of streptococci isolates was determined in polystyrene microtiter plate simultaneously and 30 minutes before streptococci entrance to the system. The results showed that 42% of mutans streptococci were strongly adherent (SA) and in non mutans streptococci, only 23.5% of isolates were found strongly adherent. The strong biofilm forming bacterium isolated was Streptococcus mutans strain22. In the next step, in the presence of probiotic strain the streptococcal adhesion were reduced, and this reduction was non significantly stronger if the probiotic strain was inoculated to the system before the oral bacteria. The Lactobacillus acidophilus had more effect on adherence of mutans streptococci than non mutans streptococci with significant difference (p < 0.05). Adhesion reduction is likely due to bacterial interactions and colonization of adhesion sites with probiotic strain before the presence of streptococci. Adhesion reduction can be an effective way on decreasing cariogenic potential of oral streptococci.

Antimicrobial Activity of Metabolites of Various Strains of Lactobacillus acidophilus

The antimicrobial activity of metabolites of eight strains of Lactobacillus acidophilus (FTDC 2804, FTDC 0785, FTDC 8592, FTDC 1295, FTDC 4793, FTDC 4462, FTDC 0582 and FTDC 2916) against Staphylococcus aureus (gram positive) and Escherichia coli (gram negative), was examined and compared using agar well diffusion method. Lactobacillus acidophilus was cultivated in two different types of dairy growth medium namely, full cream milk and skim milk. The results showed that the metabolites of all the eight strains had significant antimicrobial effect based on zone of inhibition results when compared to control. There was a statistically significant difference in the zone of inhibition data for Staphylococcus aureus and Escherichia coli among the metabolites of the eight strains cultivated in the two different growth medium. Certain L. acidophilus strains were more effective against Staphylococcus aureus, while other strains were more effective against Escherichia coli. On the other hand, the growth medium had no significant influence on the antimicrobial effect of metabolites of seven strains except L. acidophilus FTDC 4462 against Escherichia coli. As for Staphylococcus aureus, the growth medium only affected the antimicrobial effect of metabolite of strain L. acidophilus FTDC 1295, but did not affect the antimicrobial effect of metabolites of the other seven strains. It can be concluded that L. acidophilus cultivated in dairy products produced metabolites with antimicrobial property, which could provide beneficial medicinal values to human.

Probiotics Bacteria from Egyptian Infants cause Cholesterol Removal in Media and Survive in Yoghurt

One of the most significant groups of probiotic organisms are the lactic acid bacteria, commonly used in fermented dairy products. In this study, cultures were isolated from two infants. After screening for the classic properties of probiotic organisms, four promising isolates were identified as two strains of Lactobacillus acidophilus (P106, P110), strain of Lactobacillus plantarum (P164) and Lactobacillus. pentosus (P191)which were tested for capability to remove cholesterol and to deconjugate sodium taurocholate from the culture medium. Results showed that a considerable variation existed among cultures in their growth viability in the presence of bile salt, deconjugation of sodium tauro-cholate and assimilation of cholesterol from the medium. All tested strains removed less cholesterol from the broth (ranged from 4.02-24.32%) compared to those grown in broth supplemented with 0.2% bile salts (from 29.02 to 45.3). Lactobacillus acidophilus P106 appeared to be more active in bile salt hydrolase compared to the other strains, and therefore, is regarded as a suitable candidate probiotic and adjunct culture.These strains were employed to make yo-ghurt and, in order to achieve a short production time; a two-stage fermentation procedure was used with Streptococ-cus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus providing the rapid acidification. Storage trials at 4o C showed that the viability of the probiotic cultures was retained over 15 days.

Utilization of UF-Permeate for Production of β-galactosidase by Lactic Acid Bacteria

Four lactobacilli strains (Lactobacillus bulgaricus, Lactobacillus acidophilus, Lactobacilus casei and Lactobacillus reuteri) were grown in MRS broth and three lactococci strains (Streptococcus thermophilus, Lactococcus lactis subsp. Lactis and Lactococcus lactis subsp. lactis biovar. diacetilactis) were grown in M17 broth. L. reuteri and S. thermophilus were chosen on the basis of the best mean beta-galactosidase activity of 10.44 and 10.01 U/ml respectively, for further studies on permeate-based medium. The maximum production of beta-galactosidase by L. reuteri was achieved at lactose concentration of 6%, initial pH 5.0-7.5, ammonium phosphate as nitrogen source at a concentration of 0.66 g N/L and incubation temperature at 30 degrees C/24 hrs to give 6.31 U/ml. While in case of S. thermophilus, maximum beta-galactosidase production was achieved at 10% lactose concentration of permeate medium, supplemented with phosphate buffer ratio of 0.5:0.5 (KH2PO4:K2HPO4, g/L), at initial pH 6.0-6.5, ammonium phosphate (0.66g N/L) as nitrogen source and incubation temperature 35 degrees C for 24 hrs to give 7.85 U/ml.

Lactic acid bacteria fermentation of human milk oligosaccharide components, human milk oligosaccharides and galactooligosaccharides

Human milk contains about 7% lactose and 1% human milk oligosaccharides (HMOs) consisting of lactose with linked fucose, N-acetylglucosamine and sialic acid. In infant formula, galactooligosaccharides (GOSs) are added to replace HMOs. This study investigated the ability of six strains of lactic acid bacteria (LAB), Lactobacillus acidophilus, Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus reuteri, Streptococcus thermophilus and Leuconostoc mesenteroides subsp. cremoris, to digest HMO components, defined HMOs, and GOSs. All strains grew on lactose and glucose. N-acetylglucosamine utilization varied between strains and was maximal in L. plantarum; fucose utilization was low or absent in all strains. Both hetero- and homofermentative LAB utilized N-acetylglucosamine via the Embden-Meyerhof pathway. Lactobacillus acidophilus and L. plantarum were the most versatile in hydrolysing pNP analogues and the only strains releasing mono- and disaccharides from defined HMOs. Whole cells of all six LAB hydrolysed oNP-galactoside and pNP-galactoside indicating β-galactosidase activity. High β-galactosidase activity of L. reuteri, L. fermentum, S. thermophilus and L. mesenteroides subsp. cremoris whole cells correlated to lactose and GOS hydrolysis. Hydrolysis of lactose and GOSs by heterologously expressed β-galactosidases confirmed that LAB β-galactosidases are involved in GOS digestion. In summary, the strains of LAB used were not capable of utilizing complex HMOs but metabolized HMO components and GOSs.

Effects of yogurt starter cultures on the survival of Lactobacillus acidophilus

Recognized to confer health benefits to consumers, probiotics such as Lactobacillus acidophilus are commonly incorporated into fermented dairy products worldwide; among which yogurt is a popular delivery vehicle. To materialize most of the putative health benefits associated with probiotics, an adequate amount of viable cells must be delivered at the time of consumption. However, the loss in their viabilities during refrigerated storage has been demonstrated previously. This study focused on the effects of yogurt starter cultures on the survival of five strains of L. acidophilus, with emphases on low pH and acid production. Differential survival behavior between L. acidophilus strains was further analyzed. To this end, viable cell counts of L. acidophilus were determined weekly during 4 °C storage in various types of yogurts made with Streptococcus thermophilus alone, L. delbrueckii ssp. bulgaricus alone, both species of the starter cultures, or glucono-delta-lactone (GDL). All yogurt types, except for pasteurized yogurts, were co-fermented with L. acidophilus. Yogurt filtrate was analyzed for the presence of any inhibitory substance and for the amount of hydrogen peroxide. Multiplication of L. acidophilus was not affected by the starter cultures as all strains reached high level on day 0 of the storage period. Throughout the 28-day storage period, cell counts of L. acidophilus PIM703 and SBT2062 remained steady (~ 6 × 10 7 CFU/g) in yogurts made with both starter cultures, whereas those of ATCC 700396 and NCFM were reduced by a maximum of 3 and 4.6 logs, respectively. When starter cultures were replaced by GDL, all strains survived well, suggesting that a low pH was not a critical factor dictating their survival. In addition, the filtrate collected from yogurts made with starter cultures appeared to have higher inhibitory activities against L. acidophilus than that made with GDL. The presence of viable starter cultures was necessary to adversely affect the survival of some strains, as pasteurized yogurts had no effect on their survival. In particular, the inhibitory effect exerted by L. delbrueckii ssp. bulgaricus on L. acidophilus NCFM was highly pronounced than by S. thermophilus, nevertheless, the same effect was not observed on SBT2062 . The inhibition against stationary-phase NCFM cells might be caused by the elevated level of hydrogen peroxide produced by L. delbrueckii ssp. bulgaricus. Delineating factors driving the differences in survival trait among probiotic strains will lead to a more efficacious delivery of health benefits in fermented dairy products through targeted technological interventions.

Enhancement of Biological Properties of Soymilk by Fermentation

Soymilk has attracted much interest in the food industry because of its health- promoting properties. Fermentation with lactic acid bacteria is known to provide value addition to soymilk by reducing the beany flavor and content of indigestible oligosaccharides and by enhancing the bioavailability of isoflavones, resulting in a nutritious probiotic food product. In the present study, Soymilk fermentation was studied using Lactobacillus acidophilus strain isolated from ragi, and effect of soymilk supplementation on the fermentation characteristics was also investigated. Viable count of 1.99 × 109 CFU/mL sample and 630.1 U/g of β-glucosidase activity were determined in soymilk after 12 h of fermentation. Soymilk supplementation with skimmed milk powder at 5% level gave best results with viable counts of 22.9 × 109 CFU/ml sample or 212.9 × 109 CFU/g solids; 764 U/g of β-glucosidase activity, 1.44% la titratable acidity and pH of 3.9. Daidzein and genistein profile in fermented soymilk showed that 45.8% and 57.5% of respective isoflavones existing as aglycone form, indicating enhancement of the biological property of soymilk through improvement of health-relevant bioactive forms.

Probiotics, Enteric and Diarrheal Diseases, and Global Health

Enteric and diarrheal diseases are a major worldwide cause of death among children under the age of 5. In this age group, diarrhea occurs 2.5 billion times per year [1] and causes 15% of childhood deaths.[2] Diarrheal diseases claim 59 million disability-adjusted life years (DALYs), nearly all from children in low- and middle-income countries.[3] Despite this enormous burden, these numbers fail to capture the full impact of enteric and diarrheal diseases. Early and frequent exposure to intestinal pathogens begins a cycle (Figure 1A) that affects digestion, nutrient absorption, growth, and immunity.[4] Repeated infections, with either overt diarrhea or subclinical enteropathy, produce acute and chronic undernutrition,[5] which leads to more frequent and severe infections.[6] Undernutrition contributes to 53% of childhood deaths [7] and is the leading risk factor for poor health outcomes in childhood;[8] survivors are at risk for developmental deficits in growth, fitness, and cognition that persist into adulthood with devastating consequences.[4] These consequences have a multiplicative effect on calculations of DALYs from diarrheal disease.[9] Open in a separate window Figure 1 The vicious cycle of diarrhea and undernutrition in susceptible children (A) The devastating synergy between enteric infections and undernutrition is influenced by the environment, the human genome, host nutrition, and the human microbiome. Various interventions (red boxes) may inhibit progression to the next step in the cycle, minimizing both acute and chronic morbidities. (B) Employing a spectrum of disease outcome measures would lend greater insight into the pathology underlying enteric and diarrheal diseases, while providing a more complete understanding of interventions targeting basic steps of enteric and diarrheal disease pathogenesis. Adapted with permission from Wiley: Nutrition Reviews,4 copyright 2008. http://www.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1753-4887.

Effects of Oral Administration of Lactobacillus acidophilus L-92 on the Symptoms and Serum Markers of Atopic Dermatitis in Children

Background: Few studies have investigated the complementary effects of long-term oral administration of Lactobacillus acidophilus on traditional medical therapy in the treatment of patients with atopic dermatitis (AD). Methods: The Atopic Dermatitis Area and Severity Index was used to evaluate AD severity. Symptom severity was assessed using the symptom score. The effect of medical therapy was evaluated by adding the medication score, calculated as the sum of each product of the amount of steroid ointment used for therapy and its designated strength graded on a 4-point scale, to the symptom score. The complementary effect of long-term oral administration of L. acidophilus strain L-92 (L-92) as a probiotic or biogenic strain in patients with AD was evaluated using the symptom-medication score, which was calculated as the sum of the symptom score and medication score. Both a preliminary casuistic study and a double-blinded, placebo-controlled study were performed to evaluate the effects of L-92 on the symptoms of AD in children. Results: Orally administered L-92 significantly ameliorated the symptoms of AD in Japanese children. L-92 also affected the serum concentrations of thymus and activation-regulated chemokine in a time-dependent manner.Conclusions: The results of the preliminary trial and the double-blinded, placebo-controlled study revealed a complementary effect of oral L-92 on the standard medical therapy (topical application of a steroid ointment) in patients with AD that was mediated, at least in part, by alterations in the Th1/Th2 balance.

Lactobacillus acidophilus induces virus immune defence genes in murine dendritic cells by a Toll‐like receptor‐2‐dependent mechanism

Lactobacilli are probiotics that, among other health-promoting effects, have been ascribed immunostimulating and virus-preventive properties. Certain Lactobacillus spp. have been shown to possess strong interleukin-12 (IL-12) -inducing properties. As IL-12 production depends on the up-regulation of type I interferons (IFNs), we hypothesized that the strong IL-12-inducing capacity of Lactobacillus acidophilus NCFM in murine bone-marrow-derived dendritic cells (DCs) is caused by an up-regulation of IFN-β, which subsequently induces IL-12 and the double-stranded RNA binding Toll-like receptor-3 (TLR-3). The expression of the genes encoding IFN-β, TLR-3, IL-12 and IL-10 in DCs upon stimulation with L. acidophilus NCFM was determined. Lactobacillus acidophilus NCFM induced a much stronger expression of Ifn-β, Il-12 and Il-10 compared with the synthetic double-stranded RNA ligand Poly I:C, whereas the levels of expressed Tlr-3 were similar. Whole genome microarray gene expression analysis revealed that other genes related to viral defence were significantly up-regulated and among the strongest induced genes in DCs stimulated with L. acidophilus NCFM. The ability to induce IFN-β was also detected in another L. acidophilus strain (X37), but was not a property of other probiotic strains tested, i.e. Bifidobacterium bifidum Z9 and Escherichia coli Nissle 1917. The IFN-β expression was markedly reduced in TLR-2(-/-) DCs, dependent on endocytosis, and the major cause of the induction of Il-12 and Tlr-3 in DCs stimulated with L. acidophilus NCFM. Collectively, our results reveal that certain lactobacilli trigger the expression of viral defence genes in DCs in a TLR-2 manner dependent on IFN-β.

Bacteria competing with the adhesion and biofilm formation by Staphylococcus aureus

The activity of antagonistic substances produced by Pseudomonas aeruginosa and Lactobacillus acidophilus against the planktonic and sessile populations of Staphylococcus aureus strains was demonstrated. The strongest effects were caused by probiotic L. acidophilus strain - bacteriocin-like inhibitory substances (BLIS) positive. However, the S. aureus A3 growth, adhesion and biofilm formation was also limited by cell-free supernatant of L. acidophilus H-1 (BLIS negative). Moreover, competitive direct interactions were observed between staphylococci and the above bacteria, which influenced the formation of dualspecies aggregates on the surface.

Orally supplemented Lactobacillus acidophilus strain L‐92 inhibits passive and active cutaneous anaphylaxis as well as 2,4‐dinitroflurobenzene and mite fecal antigen induced atopic dermatitis‐like skin lesions in mice

Oral supplementation of lactic acid bacteria is a potential approach to the prevention and manipulation of allergic diseases such as atopic dermatitis. Our previous report showed that heat-killed Lactobacillus acidophilus strain L-92 (L-92) possessed anti-allergic properties, although its physiological function in atopic dermatitis has largely remained undefined. To evaluate the anti-allergic efficacy of L-92, we used four experimental animal models with the major features of atopic dermatitis and compared the results to those of clinically active drugs. ICR mice were passively sensitized by anti-dinitrophenyl mouse monoclonal IgE for passive cutaneous anaphylaxis (PCA), and BALB/c mice were actively sensitized by ovalbumin for active cutaneous anaphylaxis (ACA). Allergic reaction was induced by repeated exposure to 2,4-dinitroflurobenzene (DNFB) and mite (Dermatophagoides farinae) fecal allergen, in BALB/c and NC/Nga mice, respectively. Orally administrated L-92 significantly inhibited the vascular permeability increase in both PCA and ACA, and the elevation of ovalbumin-specific IgE titer in ACA. Moreover, repeated applications of DNFB and mite fecal antigen onto the BALB/c and NC/Nga mouse ear, respectively, caused clinical symptoms similar to atopic dermatitis such as ear swelling, scratching behavior and elevation of total serum IgE levels that were also moderately suppressed by L-92. In addition, L-92 treated mice exhibited lower levels of mast cells, eosinophil infiltration and Th1/Th2 cytokine expression. Our results, therefore, suggest that oral administration of L-92 might be useful for alleviating allergic symptoms.

On the viability of five probiotic strains when immobilised on various polymers

The viability of probiotic bacteria in six food‐grade polymers, at two concentrations, was evaluated in order to predict their feasibility as materials for bacterium immobilisation. Alginate and whey proteins were the most adequate polymers, except for Lactobacillus acidophilus Ki and Lactobacillus casei 01 at 2% (m/v) alginate. Xanthan gum appeared to be a potential vector for three strains. L‐carrageenan was adequate for both Bifidobacterium strains, but not for Lactobacillus at 2% (m/v). Bifidobacterium strains were not negatively affected by cellulose acetate phthalate, while the opposite held for L. acidophilus strains. Chitosan was the poorest polymer for immobilisation of probiotic bacteria.

Patterns of survival and volatile metabolites of selected Lactobacillus strains during long-term incubation in milk

The focus of this study was to monitor the survival of populations and the volatile compound profiles of selected Lactobacillus strains during long-term incubation in milk. The enumeration of cells was determined by both the Direct Epifluorescent Filter Technique using carboxyfluorescein diacetate (CFDA) staining and the plate method. Volatile compounds were analysed by the gas-chromatography technique. All strains exhibited good survival in cultured milks, but Lactobacillus crispatus L800 was the only strain with comparable growth and viability in milk, assessed by plate and epifluorescence methods. The significant differences in cell numbers between plate and microscopic counts were obtained for L. acidophilus strains. The investigated strains exhibited different metabolic profiles. Depending on the strain used, 3 to 8 compounds were produced. The strains produced significantly higher concentrations of acetic acid, compared to other volatiles. Lactobacillus strains differed from one another in number and contents of the volatile compounds.