Survival of lactic acid bacteria in a dynamic model of the stomach and small intestine: validation and the effects of bile

Survival of Listeria monocytogenes in a simulated dynamic gastrointestinal model during storage of inoculated bologna and salami slices in vacuum packages

Listeria monocytogenes counts were determined during storage (82 days, 4 degrees C) in vacuum packages of inoculated bologna and salami slices and after exposure to a simulated dynamic model of the stomach and small intestine. Variables controlled in the model included gastric emptying and gastrointestinal fluid secretion rates, gradual gastric acidification, and intestinal pH maintenance. L. monocytogenes populations increased on bologna and decreased on salami, reaching 8.7 and 1.4 log CFU/g, respectively, on day 82. Inactivation rates (IR) during gastric exposure of bologna and salami ranged from 0.079 (day 14) to 0.158 (day 57) log CFU/g/min and from 0.013 (day 42) to 0.051 (day 1) log CFU/g/min, respectively. On corresponding days, gastric IR for cells on salami were lower than on bologna, suggesting potential protective effects of the former product. However, it is also possible that the low initial L. monocytogenes levels reached with storage of salami (< or = 2.5 log CFU/g after day 27) may have resulted in slower reductions than in the high levels on bologna. Gradual decline of gastric pH allowed survival in the gastric compartment during the initial stages, which resulted in a large fraction of the cells being delivered into the intestinal compartment. Intestinal IR ranged from 0.003 to 0.048 (bologna) and from 0.002 to 0.056 (salami) log CFU/g/min throughout storage. Although findings indicated potential effects of salami against gastric killing of L. monocytogenes, any effects of the food matrix per se on the gastrointestinal survival of the pathogen were overwhelmed by the high and low contamination levels reached on bologna and salami, respectively, during storage.

Differences in survival among 13 Listeria monocytogenes strains in a dynamic model of the stomach and small intestine

Thirteen Listeria monocytogenes strains were compared for the ability to survive in a dynamic gastrointestinal model. Strains displayed various degrees of susceptibility to gastric acidity; however, strain-to-strain variations became evident mainly after 90 min of exposure (pH 2.0). Cell levels transferred to the intestine depended on initial populations, while reductions during intestinal exposure were relatively small for all strains.

Single bioreactor gastrointestinal tract simulator for study of survival of probiotic bacteria

The aim of the present study was to design an in vitro model system to evaluate the probiotic potential of food. A single bioreactor system-gastrointestinal tract simulator (GITS) was chosen for process simulation on account of its considerable simplicity compared to multi-vessel systems used in previous studies. The bioreactor was evaluated by studying the viability of four known probiotic bacteria (Lactobacillus acidophilus La-5, Lactobacillus johnsonii NCC 533, Lactobacillus casei strain Shirota, and Lactobacillus rhamnosus GG) as a function of their physiological state. L. acidophilus and L. johnsonii survived in GITS better when introduced at an early stationary or exponential phase compared to being previously stored for 2 weeks at 4 degrees C. These two species were more resistant to bile salts and survived better than L. casei and L. rhamnosus GG. The latter two species gave large losses (up to 6 log) in plate counts independent of growth state due to the bile. However, experiments with some commercial probiotic products containing Lb. GG bacteria showed much better survival compared with model food (modified deMan-Rogosa-Sharpe growth medium), thus demonstrating the influence of the food matrix on the viability of bacteria. The study demonstrated that GITS can be successfully used for evaluation of viability of probiotic bacteria and functionality of probiotic food.

Conjugated linoleic acids produced by Lactobacillus dissociates IKK-gamma and Hsp90 complex in Helicobacter pylori-infected gastric epithelial cells

Although probiotics have been reported to reduce the gastric inflammatory response to Helicobacter pylori infection, little information is available regarding the molecular mechanisms behind this reduction. This study investigates the role of conjugated linoleic acids (CLA) produced by probiotics in interactions of IkappaB kinase (IKK) and heat shock protein 90 (Hsp90) to activate the nuclear factor-kappaB (NF-kappaB) signaling pathway in human gastric epithelial cells infected with H. pylori. Conditioned medium (CM) containing Lactobacillus acidophilus-producing CLA significantly inhibited the activated NF-kappaB signals and the upregulated expression of interleukin-8 (IL-8) in MKN-45 cells infected with H. pylori. Pretreatment with CM with CLA attenuated the increased IKK activity induced by H. pylori. Transfection of siRNA for IKK-beta dramatically reduced H. pylori-induced IkappaBalpha phosphorylation, but siRNA for IKK-alpha had little effect on IkappaBalpha phosphorylation, although the siRNA for IKK-alpha significantly decreased IL-8 production. Furthermore, Hsp90 was associated with IKK-alpha and IKK-gamma in H. pylori-infected cells, and CM with CLA dissociated the complex between Hsp90 and IKK-gamma. These results suggest that CLA produced by probiotics has anti-inflammatory activity in gastric epithelial cells infected with H. pylori via dissociation of the IKK-gamma and Hsp90 complex.

Effect of the trehalose levels on the screening of yeast as probiotic by in vivo and in vitro assays

Probiotics are viable defined microorganisms (bacteria or yeasts) that exert a beneficial effect on the health of the host when ingested in adequate amounts. Screening for such biotherapeutic agents is commonly performed by in vitro assays simulating gastrointestinal environment to determine the ability to survive in the digestive tract. In the present study, the possibility of extrapolation of data obtained in in vitro assays to in vivo conditions was studied using five Saccharomyces cerevisiae strains isolated from Brazilian Atlantic rain forest. Trehalose contents and survival after exposure to a combination of physiological stresses generally found in the gastrointestinal tract of humans were determined for the five yeasts and compared to the behavior of Saccharomyces boulardii, a well-known probiotic. The results were completed with the colonization capacity of the gastrointestinal tract of gnotobiotic mice by these yeast strains. Some results obtained by in vitro assays are not confirmed by in vivo experiments, indicating that the extrapolation cannot be always done.

Evaluation of a dynamic in vitro model to simulate the porcine ileal digestion of diets differing in carbohydrate composition

The aim of the study was to assess the ability of a dynamic in vitro model to determine the digestibility of OM, CP, and starch compared with a validated, static, in vitro method and in vivo ileal digestibility obtained from growing pigs fitted with a T-cannula. Five experimental diets with different carbohydrate types and level were assessed: a standard corn-based diet (ST) or the same diet with coarse ground corn (CC), 8% sugar beet pulp (BP), 10% wheat bran (WB), or 8% sugar beet pulp and 10% wheat bran (HF). In the in vivo experiment, diets CC and HF reduced (P = 0.015) ileal digestibility of OM compared with the ST diet. The inclusion of sugar beet pulp reduced (P = 0.049) ileal CP digestibility of the BP diet. This reduction was not statistically significant when sugar beet pulp was combined with the wheat bran in the HF diet. No differences were shown for in vivo starch digestibility among diets. With the static in vitro method, the OM disappearance was greater than that observed in the in vivo experiment. In this static method, the BP and HF diets reduced (P = 0.004 and < 0.001, respectively) the disappearance of the OM compared with the ST diet. The coarse grinding of corn did not alter OM digestibility but decreased (P = 0.005) the starch digestibility. The R(2) between the in vivo results and the static in vitro methods for OM and starch digestibility was 0.99 when the CC diet was not considered. The dynamic in vitro model yielded OM and CP digestibility coefficients comparable with those obtained in vivo for the ST and CC diets. However, the values were considerably affected by the incorporation of the fibrous ingredients. Diets BP, WB, and HF had decreased (P = 0.009, 0.058, and 0.004, respectively) OM digestibility compared with the ST diet. Protein digestibility was also decreased (P < 0.001, P = 0.019, and P = 0.003, respectively) with the BP, WB, and HF diets compared with the ST diet. However, digestibility was decreased to a greater extent in the BP diet than in the WB and HF diets, both of which contained wheat bran. The R(2) between the dynamic in vitro model and the in vivo results for CP digestibility was 0.99 when the CC diet was not considered. No differences were detected for starch digestibility among the diets with the dynamic in vitro model. This dynamic in vitro model yielded ileal digestibility results comparable with those obtained in vivo for CP and OM with a corn-soybean diet, or with a diet including coarse corn, but it underestimated digestibility when fibrous ingredients were included in the diet.

A review of the physiology of the canine digestive tract related to the development ofin vitrosystems

Food and nutrition studies in animals and human beings often meet with technical difficulties and sometimes with ethical questions. An alternative to research in living animals is the dynamic multicompartmentalin vitromodel for the gastrointestinal tract described by Minekuset al.(1995) and Havenaar & Minekus (1996). The dynamic conditions that are simulated in this model are peristaltic movements, transit times, pH responses, secretion of enzymes and electrolytes and absorption of nutrients and water. To obtain data for anin vitromodel of the dog gastrointestinal tract, the literature was surveyed for physiological responses to different types of dog food. These included: values of enzyme activities, electrolyte concentrations, gastric emptying and intestinal transit times, pH values, secretion and composition of bile and absorption rates in different parts of the dog gastrointestinal tract. The review focuses on research carried out on healthy, adult dogs of 10–20 kg and on parameters related to the oral cavity, stomach and small intestine. This literature research gives sufficient data on the physiology of the canine digestive tract for the development of anin vitrodynamic model that adequately simulates the functions of the stomach and small intestine of the dog.

Selection of Lactobacillus sp. PSC101 that produces active dietary enzymes such as amylase, lipase, phytase and protease in pigs

This study was carried out to screen lactic acid bacteria that produce active dietary enzymes, such as amylase, lipase, phytase, and protease, using a two-step process in pigs. We isolated a total of 210 and 132 strains of bacteria, grown under aerobic and anaerobic conditions, respectively, in Man Rogosa Sharpe agar containing 0.13% bile after treatment of intestinal samples at pH 3 for 30 min. From fecal samples, a total of 134 aerobic and 111 anaerobic strains were isolated in the same manner. In the second screening test, we selected four strains that produced four dietary enzymes from isolates obtained in the first screening test. Each strain was characterized as lactobacilli based on the following criteria: rod shape, negative for catalase, Gram positive, and lack of acute oral toxicity in mice. Of these four strains, we finally selected Lactobacillus spp. PSC101, which was resistant to pH 3 for 8 h and grew in the presence of 1% bile. In summary, Lactobacillus sp. PSC101 may be a strong probiotic candidate in swine due to its resistance to both acid and bile, its production of dietary enzymes that promote animal growth, and its non-toxic nature in mice.

Screening from pickled vegetables the potential probiotic strains of lactic acid bacteria able to inhibit the Salmonella invasion in mice

AIMS

To screen from pickled vegetables the potential probiotic lactic acid bacteria (LAB) strains with antagonistic activity against Salmonella invasion in host.

METHODS AND RESULTS

Probiotic properties including acid and bile tolerance as well as inhibition on pathogenic bacteria were used for screening of LAB strains from pickled vegetables. Two strains, i.e Pediococcus pentosaceus MP12 and Lactobacillus plantarum LAP6, were selected and further assayed for their activities against Salmonella invasion in mouse liver and spleen. For these two LAB strains, strain LAP6 was able to adhere to the mouse intestinal epithelium cells.

CONCLUSIONS

In screening of the probiotic strains able to inhibit the Salmonella invasion in host, factors other than the adherence to host intestinal epithelium may contribute some roles.

SIGNIFICANCE AND IMPACT OF THE STUDY

Probiotic LAB strains with activity against Salmonella invasion in host could be isolated from vegetable origins. These strains may be used for vegetable processing.

Spontaneous Lactobacillus delbrueckii phage-resistant mutants with acquired bile tolerance

Three commercial phage-sensitive strains of Lactobacillus delbrueckii (strains Ab(1), YSD V and Ib(3)) and four spontaneous phage-resistant mutants (strains A(7), A(17), V(2) and I(39)) isolated from them, all with a probiotic potential previously demonstrated were studied for their tolerance of bile salts (ox gall). Minimal Inhibitory Concentrations (MICs) ranged from 0.30% to 0.35% (w/v) of ox gall. These strains were exposed to gradually increasing concentrations of ox gall with the aim of isolating bile resistant derivatives. Stable derivatives able to tolerate up to 0.9% of ox gall were obtained from L. delbrueckii Ab(1), as well as from its spontaneous phage-resistant mutants A(7) and A(17). Random Amplified Polymorphic DNA (RAPD-PCR) analysis revealed a strong genetic homology between the ox gall-tolerant derivatives and their respective non-adapted original strains. These derivatives maintained, in general, the phage resistance phenotype of the non-adapted strains, with only one exception (phage-resistant mutant A(7)). After progressive ox gall adaptation, the phage-resistant mutant A(7) also exhibited progressive reversion of the phage resistance phenotype. The derivative with the highest ox gall-acquired tolerance (A(7)(0.9)) became sensitive to the phage, but derivatives with low (A(7)(0.3)) and intermediate (A(7)(0.6)) ox gall-acquired tolerance retained phage resistance. The technological properties of ox gall derivatives were comparable to those of their respective parent strains. However, the cells of the former were smaller than those of the original strains. Finally, the tolerant derivatives grew faster in the presence of ox gall than the parent strains. Our results demonstrated that it was possible to obtain, by a natural selection strategy, probiotic strains with acquired ox gall-tolerance from three (L. delbrueckii Ab(1) and their phage-resistant mutants A(7) and A(17)) of seven tested strains. Since such derivatives keep both phage resistance and other useful technological properties, they could be used for production of functional foods.

Probiotic intervention decreases serum gastrin-17 in Helicobacter pylori infection

BACKGROUND

Previously we showed that a probiotic combination with L. rhamnosus GG was beneficial as an adjuvant therapy during H. pylori eradication.

AIM

To evaluate whether probiotic combination with LGG adheres to the upper gastrointestinal mucosa and modifies H. pylori colonisation and H. pylori induced inflammation.

METHODS

Thirteen patients referred for gastroduodenoscopy received a drink consisting of equal doses (2.5x10(9)CFU) of LGG, L. rhamnosus LC705, Propionibacterium freudenreichii JS and Bifidobacterium lactis Bb12 daily. Recovery of probiotics in biopsies (antrum, corpus, duodenum) and faecal samples was evaluated by strain-specific quantitative polymerase chain reaction. H. pylori colonization and gastric inflammation was investigated by urease activity ((13)C-urea breath test), histology and serum pepsinogen I, II and gastrin-17 measurements.

RESULTS

Twelve patients were fully investigated; of these three of the patients had LGG adhering to the biopsies at end of the intervention. Other probiotic strains were not detected, even though the recovery of all individual probiotic strains from the faeces was significantly increased (p<0.01). After the treatment, the level of (13)C-urea breath test (p=0.063) and gastrin-17 (p=0.046) decreased.

CONCLUSIONS

The decreases in (13)C-urea breath test and gastrin-17 indicate that the probiotic combination exerts a beneficial effect on gastric mucosa in H. pylori infected patients. LGG showed marginal ability to adhere to the upper gastrointestinal tract mucosa.

Helicobacter pylori and probiotics

Helicobacter pylori infection, a highly prevalent pathogen, is a major cause of chronic gastritis and peptic ulcer and a risk factor for gastric malignancies. Antibiotics-based H. pylori eradication treatment is 90% effective. However, it is expensive and causes side effects and antibiotic resistance. Probiotics could present a low-cost, large-scale alternative solution to prevent or decrease H. pylori colonization. A literature search of the MEDLINE database (1966-2006) has been performed selecting all in vitro, animal, and human fully published English-language studies dealing with H. pylori and probiotics. Probiotics had an in vitro inhibitory effect on H. pylori. Animal studies demonstrated that probiotic treatment is effective in reducing H. pylori-associated gastric inflammation. Seven of 9 human studies showed an improvement of H. pylori gastritis and decrease in H. pylori density after administration of probiotics. The addition of probiotics to standard antibiotic treatment improved H. pylori eradication rates (81% vs. 71%, with combination treatment vs. H. pylori-eradication treatment alone; chi(2)test: P=0.03). Probiotic treatment reduced H. pylori therapy-associated side effects (incidence of side effects: 23% vs. 46%, with combination therapy vs. H. pylori-eradication treatment alone; chi(2)test: P=0.04). No study could demonstrate the eradication of H. pylori infection by probiotic treatment. So long-term intake of products containing probiotic strains of probiotics may have a favorable effect on H. pylori infection in humans, particularly by reducing the risk of developing disorders associated with high degrees of gastric inflammation.

Characterization of Lactobacillus plantarum PH04, a potential probiotic bacterium with cholesterol-lowering effects

The bacterium Lactobacillus plantarum PH04 was isolated from infant feces and tested positive for bile/acid tolerance and bile salt hydrolase activity. It was evaluated as a potential probiotic with cholesterol-lowering effect. Bile salt hydrolase activity was nine times greater in stationary phase than in exponential phase cells and increased when the cells were exposed to conjugated bile salts. L. plantarum PH04 was resistant to seven of nine antibiotics tested and did not produce beta-glucuronidase. L. plantarum PH04 was fed to hypercholesterolemic mice at numbers of 10(7) CFU per mouse per day for 14 days. Compared with a control group, the serum cholesterol and triglycerides were respectively 7 and 10% lower in the group fed L. plantarum PH04, and fecal lactic acid bacteria increased while no any significant differences (P<0.05) in body weight, visceral weigh index or bacteria translocation between two groups were observed. The results indicated that L. plantarum PH04 might be effective as a probiotic with cholesterol-lowering activities.

Intracellular accumulation of trehalose protects Lactococcus lactis from freeze-drying damage and bile toxicity and increases gastric acid resistance

Interleukin-10 (IL-10) is a promising candidate for the treatment of inflammatory bowel disease. Intragastric administration of Lactococcus lactis genetically modified to secrete IL-10 in situ in the intestine was shown to be effective in healing and preventing chronic colitis in mice. However, its use in humans is hindered by the sensitivity of L. lactis to freeze-drying and its poor survival in the gastrointestinal tract. We expressed the trehalose synthesizing genes from Escherichia coli under control of the nisin-inducible promoter in L. lactis. Induced cells accumulated intracellular trehalose and retained nearly 100% viability after freeze-drying, together with a markedly prolonged shelf life. Remarkably, cells producing trehalose were resistant to bile, and their viability in human gastric juice was enhanced. None of these effects were seen with exogenously added trehalose. Trehalose accumulation did not interfere with IL-10 secretion or with therapeutic efficacy in murine colitis. The newly acquired properties should enable a larger proportion of the administered bacteria to reach the gastrointestinal tract in a bioactive form, providing a means for more effective mucosal delivery of therapeutics.

Lactobacillus salivarius CECT 5713, a potential probiotic strain isolated from infant feces and breast milk of a mother-child pair

In this study, Lactobacillus salivarius CECT 5713 was originally isolated from feces of a one-month-old breast-fed infant. Since it has been suggested that the gut microbiota of breast-fed infants reflects that of the maternal breast milk, we investigated if this specific strain was present in breast milk of the respective mother. RAPD and PFGE analysis revealed the presence of the strain L. salivarius CECT 5713 in this biological fluid. To our knowledge, this is the first report of a L. salivarius strain isolated from breast milk. L. salivarius CECT 5713 produced l-lactate, acetate and hydrogen peroxide, which may be responsible for its antimicrobial activity against most of the indicator organisms used in this study; in addition, this strain showed a high survival rate after exposition to conditions simulating those found in the gastrointestinal tract. Finally, it was strongly adhesive to Caco-2 and HT-29 cells did not produce biogenic amines and were unable to degrade gastric mucin in vitro.

Lactobacillus spp. with in vitro probiotic properties from human faeces and traditional fermented products

Lactobacillus strains from traditional African fermented milk products, as well as human intestinal isolates were identified and investigated in vitro for their technological and functional characteristics as potential new probiotic strains. To test survival under gastrointestinal conditions, first the protective effect of milk and the effects of medium composition, lysozyme, pepsin, and pH of the medium on bacterial viability were assessed in vitro using the Plackett-Burman statistical model and the commercially used L. johnsonii LA1 probiotic strain. The use of either an artificial gastric electrolyte solution or MRS did not play a significant role in the viability of the cultures, while lysozyme, acidic conditions (pH 2.5), pepsin and the presence of milk significantly influenced the survival of the strain. Therefore, these parameters were selected as important test variables in a model stomach passage survival trial. Five strains identified as L. plantarum and two identified as L. johnsonii showed good survival under simulated gastrointestinal conditions. These selected strains also showed antimicrobial activity, probably due to production of organic acids. All strains exhibited bile salt hydrolase activity, while only the L. plantarum strains showed beta-galactosidase activity.

Systematic review: are probiotics useful in controlling gastric colonization by Helicobacter pylori?

Helicobacter pylori is a highly prevalent pathogen considered as an aetiological factor for gastroduodenal ulcers, and a risk factor for gastric adenocarcinoma and lymphoma in humans. Most subjects colonized by this micro-organism are asymptomatic and remain untreated. In symptomatic patients, the antibiotic treatment has a high cost and is not 100% effective because of resistance to antibiotics and to moderate patient compliance. This review discusses the role of probiotics as alternative solutions to assist in the control of H. pylori colonization in at-risk populations. The evidence that some strains of Lactobacillus and Bifidobacterium are able to inhibit H. pylori growth through the release of bacteriocins or organic acids, and may also decrease its adhesion to epithelial cells, is reviewed. In addition, probiotics have a possible role in the stabilization of the gastric barrier function and the decrease of mucosal inflammation. Other aspects that are considered are the contribution of probiotics to the healing of the gastric mucosa linked to their antioxidant and anti-inflammatory properties. Clinical trials in colonized adults and children are reviewed, and suggest that probiotics do not eradicate H. pylori but maintain lower levels of this pathogen in the stomach; in combination with antibiotics, probiotics may increase eradication rate and/or decrease adverse effects. Papers suggesting similar effects on H. pylori by foodstuffs such as berry juice and some milk proteins are quoted. Regular intake of these and other dietary products might constitute a low-cost, large-scale alternative solution applicable for populations at-risk for H. pylori colonization.

Adhesion of Lactobacillus plantarum 423 and Lactobacillus salivarius 241 to the intestinal tract of piglets, as recorded with fluorescent in situ hybridization (FISH), and production of plantaricin 423 by cells colonized to the ileum

AIMS

To determine which intestinal section of pre and postweaned piglets are colonized by Lactobacillus plantarum 423 and Lactobacillus salivarius 241, and follow production of plantaricin 423 in a gastro-intestinal model.

METHODS AND RESULTS

Lactobacillus plantarum 423 and Lact. salivarius 241, single or in combination, were administered to 1-, 14- and 28-day-old (postweaned) piglets. According to results obtained by fluorescent in situ hybridization (FISH), Lact. plantarum 423 adhered strongly to the ileum and posterior colon and Lact. salivarius 241 to the duodenum in preweaned piglets. High numbers of strain 241 were recorded in the duodenum and posterior colon of postweaned piglets, whereas strain 423 remained localized to the ileum. Lowering in Enterococcus faecalis cell numbers were recorded when preweaned piglets were challenged with strain 241. Plantaricin 423 was produced for 96 h in the ileum section of a gastro-intestinal model.

CONCLUSIONS

Lactobacillus plantarum 423 and Lact. salivarius 241 adhere to different sections of the intestinal tract, depending on the piglet's age. Ent. faecalis were inhibited in vivo, probably by plantaricin 423.

SIGNIFICANCE AND IMPACT OF THE STUDY

Fluorescent in situ hybridization proved valuable in the detection of probiotic bacteria adhered to the intestine. This is the first report of bacteriocin production in a model simulating the porcine gastro-intestinal tract.

Probiotics and Prebiotics in Human Health

Probiotic bacteria are found in the intestines of humans and other mammals where they provide health benefits to the host. They do so by (1) providing nutrients and cofactors, (2) successfully competing with pathogens, and (3) stimulating host immune responses by producing specific polysaccharides. These bacteria can also alleviate the symptoms of disease-related metabolic disorders. Prebiotics are substances, usually poorly metabolized polysaccharides and oligosaccharides, that cannot be ingested effectively by the animal. They stimulate the growth of intestinal probiotic bacteria, which can utilize these carbohydrates, thereby promoting health of the organism. Genetic engineering has proven useful for the design of probiotic bacteria that counteract the symptoms of genetic and age-related diseases. Can these bacteria be engineered, through human-promoted accelerative evolution, so that they stimulate their own growth and that of other probiotic bacteria so as to crowd pathogens out of the intestine?

Effect of regular ingestion of Saccharomyces boulardii plus inulin or Lactobacillus acidophilus LB in children colonized by Helicobacter pylori

AIM

To evaluate the effect of a probiotic, Lactobacillus acidophilus LB (LB), or a synbiotic, Saccharomyces boulardii plus inulin (SbI), on Helicobacter pylori (Hp) colonization in children.

SUBJECTS AND METHODS

A clinical trial was carried out in a school from a low socio-economic area of Santiago. Two hundred and fifty-four asymptomatic children (8.40+/-1.62 y) were screened for Hp by the (13)C-Urea Breath Test ((13)C-UBT). Hp-positive children were randomly distributed into three groups to receive either antibiotic treatment (lanzoprazole, clarythromycin and amoxicillin) for 8 d, or SbI or LB daily for 8 wk. A second (13)C-UBT was carried out at this time. Spontaneous clearance was evaluated in the same way in 81 infected, untreated children. The differences in the delta(13)CO(2) over baseline values before and after treatments (?DOB) were evaluated.

RESULTS

182 subjects (71.7%) were colonized by Hp, and 141 of them completed their treatment (22.5% dropout). Hp was eradicated in 66%, 12% and 6.5% of the children from the Ab, SbI and LB groups, respectively, while no spontaneous clearance was observed in the children without treatment. A moderate but significant difference in ?DOB was detected in children receiving living SbI (-6.31; 95% CI: -11.84 to -0.79), but not in those receiving LB (+0.70; 95% CI: -5.84 to +7.24).

CONCLUSION

S. boulardii seems promising as an agent that interferes with Hp in colonized individuals. More studies are needed to confirm these results and to elucidate the mechanisms by which Sb inhibits Hp.

Effects of cryoprotectants on the viability and activity of freeze dried recombinant yeasts as novel oral drug delivery systems assessed by an artificial digestive system

The aim of this study was to investigate, in a gastric-small intestinal system TIM-1, the effect of cryoprotectants on the survival of freeze-dried Saccharomyces cerevisiae expressing the heterologous P450 73A1 and their ability to convert trans-cinnamic acid into p-coumaric acid. Yeasts were lyophilized in suspensions of trehalose, maltose, lactose, or a milk proteins/trehalose mix. Freeze-dried or native yeasts and trans-cinnamic acid were introduced simultaneously into TIM-1 at the beginning of digestion. Yeast survival rate was evaluated by cell counting in the ileal effluents. P450 73A1 activity was followed by HPLC assay of p-coumaric acid. Freeze-dried yeasts showed high tolerance to digestive conditions. Nevertheless, their survival rate was lower than that of non-dried cells (around 80% whatever the protective agent vs. 96%). The ability of recombinant freeze-dried S. cerevisiae to perform a bioconversion reaction in the digestive tract was shown with all the protectants. The highest trans-cinnamic acid conversion rate (24 vs. 41% for native yeasts) was obtained with the milk proteins/trehalose mix. These results show that freeze-drying might be considered for the pharmaceutical formulation of new drug delivery systems based on orally administered recombinant yeasts and that TIM-1 could be a helpful tool for the pre-screening of oral dosage forms.

Antagonistic activity against Salmonella infection in vitro and in vivo for two Lactobacillus strains from swine and poultry

In this study, we isolated two lactobacillus strains, i.e., strain LAP5 and LF33, from swine and poultry, respectively, and showed that both strains were acid as well as bile tolerant and were able to adhere to the cultured human intestinal cell lines, such as Int-407 and Caco-2 cells, and to the intestinal epithelium cells isolated from swine, poultry and mouse (BALB/c). Both of these LAB strains were shown to inhibit the growth of Escherichia coli, Salmonella typhimurium, Staphylococcus aureus and Bacillus cereus. When these two LAB strains were evaluated for their antagonistic activity against Salmonella (S. typhimurium) invasion to cultured human intestinal cell line Int-407 and to mouse (BALB/c) liver and spleen, these two LAB strains were found to have significant antagonistic effect.

Characterization of a reuterin-producing Lactobacillus coryniformis strain isolated from a goat's milk cheese

Lactobacillus coryniformis CECT 5711, a strain isolated from a goat's milk cheese, displayed a broad-spectrum antimicrobial activity; as a consequence, its ability to produce the antagonistic compounds associated to lactic acid bacteria, including bacteriocins, hydrogen peroxide, lactic acid, acetic acid, and reuterin (3-hydroxypropionaldehyde, 3-HPA) was investigated. Production of bacteriocins or hydrogen peroxide by this strain could not be detected. However, in addition to lactic acid and acetic acid, it produced reuterin and cobalamin, a cofactor required for conversion of glycerol to 3-HPA through a glycerol dehydratase. The gene encoding a glycerol dehydratase subunit was detected by PCR and the corresponding amplicon was sequenced. This strain showed a high survival after exposition to conditions simulating those existing in the gastrointestinal tract as well as a notable ability to adhere to intestinal cells, which suggests that its reuterin-producing ability may be used for the host benefit. In addition, the strain showed a strong beta-galactosidase activity. Production of biogenic amines and degradation of mucin could not be detected.

Radical scavenging activity and stability of betalains from Beta vulgaris hairy root culture in simulated conditions of human gastrointestinal tract

Stability and radical scavenging activity of betalains, biosynthesized by Beta vulgaris hairy root culture were investigated at different pH values, bile salts concentration, as well as at the in vitro conditions of gastrointestinal tract. It was established that pH below 3 and concentrations of the bile salts up to 4% had no great influence on betalains stability. At the in vitro conditions of gastrointestinal tract betalains are relatively stable, as their radical scavenging activity decrease from 75% inhibition of 2,2-diphenyl-1-picrylhydrazyl (DPPH*) to about 38%.

A dynamic model that simulates the human upper gastrointestinal tract for the study of probiotics

A dynamic model of the human upper gastrointestinal (GI) tract was designed to better simulate conditions of ingestion and digestion, by including a food matrix as part of the model design. The dynamic model consisted of two reactors maintained at 37 degrees C, one simulating stomach conditions and the other simulating duodenum conditions. The model was tested by comparing survival of bacteria isolated from humans (Bifidobacterium infantis, Lactobacillus johnsonii, Lactobacillus rhamnosus, and Lactobacillus acidophilus) animals (Bifidobacterium animalis, 2 strains), and fermented dairy products (Bifidobacterium longum, Lactobacillus kefir, Lactobacillus kefirgranum, and Leuconostoc mesenteroides) with their survival as determined by conventional methods. Five strains were not able to survive (>3 log reduction) 15 min in a medium acidified at pH 2.0 using the conventional testing method, but survival was improved significantly for some strains in the dynamic model. Two strains (Bifidobacterium animalis ATCC 25527 and Lactobacillus johnsonii La-1 NCC 533) showed good survival with both methods. The dynamic model was shown to better represent the events during upper GI tract transit than the conventional methods, by incorporation of a food matrix to buffer the gastric acidity and therefore expose bacteria to pH levels found in vivo before, during, and after a meal.

Isolation and characterization of anti-Salmonella lactic acid bacteria from the porcine gastrointestinal tract

AIMS

To identify lactic acid bacteria (LAB) of porcine intestinal origin with anti-Salmonella activity.

METHODS AND RESULTS

Samples were obtained from pig faeces and caeca and screened for the presence of anti-Salmonella LAB. The 11 most promising isolates were identified as belonging to the genera Lactobacillus and Pediococcus. The LAB exhibited large variation in their ability to survive in simulated gastric juice at pH 1.85. While Lactobacillus johnsonii species survived at levels of 80% for up to 30 min, Lactobacillus pentosus species declined to <0.001% in that time. All isolates tolerated porcine bile at a concentration of 0.3% (w/v), with some isolates capable of growth in the presence of up to 5% (w/v) bile. The ability of the LAB isolates to prevent Salmonella invasion of intestinal epithelial HT-29 cells varied, with reductions of between 30% (Lact. pentosus) and 80% (Lactobacillus murinus spp.) observed.

CONCLUSIONS

LAB of porcine origin were observed to survive simulated passage through the GIT and inhibit growth of Salmonella and its invasion of the intestinal epithelium.

SIGNIFICANCE AND IMPACT OF THE STUDY

The data demonstrate that some porcine intestinal LAB isolates may offer potential as probiotics for the reduction of Salmonella carriage in pigs.

Probiotic potential of 3 Lactobacilli strains isolated from breast milk

Breast milk is an important factor in the initiation, development, and composition of the neonatal gut microbiota. In a previous study, the authors isolated lactic acid bacteria from milk of healthy mothers. Since some of the identified isolates belonged to the genus Lactobacillus, the objective of this work was to evaluate the probiotic potential of 2 Lactobacillus gasseri and 1 Lactobacillus fermentum strains. Different assays, including survival to conditions simulating those existing in the gastrointestinal tract, production of antimicrobial compounds, adherence to intestinal cells, production of biogenic amines, degradation of mucin, enzymatic profile, and pattern of antibiotic resistance, were performed. Globally, the results showed that the probiotic potential of lactobacilli isolated from milk of healthy mothers is, at least, similar to that of the strains commonly used in commercial probiotic products. This fact, together with the presence of prebiotic substances, indicates that breast milk is a natural synbiotic food.

Living recombinant Saccharomyces cerevisiae secreting proteins or peptides as a new drug delivery system in the gut

New strategies to prevent or treat diseases have been focusing on innovative approaches, such as the oral administration of living recombinant micro-organisms delivering active compounds in the digestive environment. The survival rate and the ability of two recombinant Saccharomyces cerevisiae strains (WppV(5)H(6) and WppGSTV(5)H(6)) to initiate the synthesis and secrete either a model peptide (peptide-V(5)H(6), MW: 5.6 kDa) or a model protein (glutathione-S-transferase-V(5)H(6), MW: 31.5 kDa) were studied in a gastric-small intestinal system simulating human digestive conditions. The WppV(5)H(6) and WppGSTV(5)H(6) strains respectively showed 83.1%+/-9.6 (n=3) and 95.3%+/-22.7 (n=4) survival rates in the model upper digestive tract after 270 min of digestion. The secretion products were detected as early as 90 min after the yeast intake/gene induction in each compartment of the in vitro system, but mostly in the jejunum and ileum. The GST-V(5)H(6) concentrations in the digestive medium reached 15 ng ml(-1), close to values measured in batch cultures. These results open up new opportunities for the set up of drug delivery systems based on engineered yeasts secreting compounds directly in the digestive tract. The main potential medical applications include the development of oral vaccines, the correction of metabolic disorders and the in situ production of biological mediators.

Probiotics and prebiotics: role in clinical disease states

Parents of pediatric patients are seeking alternatives to conventional therapy in the prevention and treatment of gastrointestinal disease states because of therapeutic failures caused by the increased incidence of antibiotic resistance. One such alternative is the use of probiotics and prebiotics to stimulate health-promoting indigenous flora to affect pathogen colonization and expression of disease. Probiotics are live flora given in oral quantities that allow for colonization of the colon. Probiotics are given as functional foods or dietary supplements, and function to activate the mucosal immune system and prevent pathogen colonization and translocation by strengthening the mucosal barrier, interfering with pathogen colonization, and in some instances, producing secretory antibacterial substances. Prebiotics are nondigestible carbohydrates, principally oligosoccharides, that are fermented by colonic commensals, stimulating their proliferation and producing short-chain fatty acids. Both protective nutrients have been shown to reduce the incidence and severity of infantile diarrhea, particularly rotaviral gastroenteritis, prevent antibiotic-induced diarrhea, and prevent and treat intestinal food allergy. With additional multicenter clinical trial confirmations, these substances may become routine in the care of infants and young children.

A dynamic artificial gastrointestinal system for studying the behavior of orally administered drug dosage forms under various physiological conditions

PURPOSE

The purpose of this study was to demonstrate the potential of a dynamic, multicompartmental in vitro system simulating the human stomach and small intestine (TIM-1) for studying the behavior of oral drug dosage forms under various physiological gastrointestinal conditions.

METHODS

Two model drug compounds were studied in TIM-1: a lyophilized Lactobacillus strain and paracetamol (acetaminophen). The Lactobacillus survival rate was determined by bacterial counting in the gastric and ileal effluents while simulating the conditions of the gastrointestinal tract of infants or adults. The availability for absorption of paracetamol from two oral dosage forms was investigated by measuring the drug concentration in jejunal dialysis fluid. The effect of gastrointestinal passage time and food intake on paracetamol absorption was also studied.

RESULTS

The Lactobacillus survival rate in both gastric and ileal effluents was higher during simulation of the infant compared to adult conditions. We also showed that (i) paracetamol absorption was faster when it was administered as a free powder than in sustained-release tablet form, (ii) a slow passage time resulted in a delay in the absorption of paracetamol, and (iii) there was a lower rate of absorption when paracetamol was ingested with a standard breakfast as opposed to water. The in vitro results were consistent with in vivo data, showing the predictive value of TIM-1.

CONCLUSIONS

TIM-1 is a powerful tool for supplying valuable information about the effects of various gastrointestinal conditions on biopharmaceutical behavior and efficacy of drug delivery systems in the development of oral formulations.

Microbiological characterization of wet wheat distillers' grain, with focus on isolation of lactobacilli with potential as probiotics

Wet wheat distillers' grain (WWDG), a residue from ethanol fermentation, was examined from a microbiological perspective. After storage, WWDG was characterized by a high content of lactobacilli, nondetectable levels of other bacteria, occasional occurrence of yeasts, and a pH of about 3.6 and contained a mixture of lactic acid, acetic acid, and ethanol. The composition of lactobacilli in WWDG was simple, including primarily the species Lactobacillus amylolyticus, Lactobacillus panis, and Lactobacillus pontis, as determined by 16S rRNA gene sequencing. Since the use of WWDG as pig feed has indicated a health-promoting function, some relevant characteristics of three strains of each of these species were examined together with basal physiological parameters, such as carbohydrate utilization and growth temperature. Seven of the strains were isolated from WWDG, and two strains from pig feces were included for comparison. It was clear that all three species could grow at temperatures of 45 to 50 degrees C, with L. amylolyticus being able to grow at temperatures as high as 54 degrees C. This finding could be the explanation for the simple microflora of WWDG, where a low pH together with a high temperature during storage would select for these organisms. Some strains of L. panis and L. pontis showed prolonged survival at pH 2.5 in synthetic stomach juice and good growth in the presence of porcine bile salt. In addition, members of all three species were able to bind to immobilized mucus material in vitro. Especially the isolates from pig feces but, interestingly, some isolates from WWDG as well possessed properties that might be of importance for colonization of the gastrointestinal tracts of pigs.

The in vivo assessment of safety and gastrointestinal survival of an orally administered novel probiotic, Propionibacterium jensenii 702, in a male Wistar rat model

This study aimed to evaluate in vivo gastrointestinal survival and safety of orally administered probiotic bacterium, Propionibacterium jensenii 702, using a male Wistar rat model. A high dose of 10(10) cfu/rat/day of P. jensenii 702 was fed to each rat for 81 days. The repeated dose toxicity and translocation of P. jensenii 702 into rat tissues were evaluated, along with the rat faecal beta-glucuronidase activities and dairy propionibacteria counts. Results showed that P. jensenii 702 had no adverse effect on general health status, body weight gain, visceral organs and faecal beta-glucuronidase activities. No viable cells of P. jensenii 702 were recovered from blood and tissue samples (mesenteric lymph nodes, liver and spleen) of rats, and no treatment-associated illness or death was observed. Faecal dairy propionibacteria counts reached 10(8) cfu/g after 36 days treatment and remained between 10(8)-10(9) cfu/g till the end of 81 days treatment. The results indicate that P. jensenii 702 was able to survive the in vivo gastrointestinal tract transit of rats, with no adverse affects on the animals. However, further human clinical trials are required before strain P. jensenii 702 could be incorporated into food for human consumption as probiotics.

Protection of bifidobacteria encapsulated in polysaccharide-protein gel beads against gastric juice and bile

Bifidobacterium cells were encapsulated in a mixed gel composed of alginate, pectin, and whey proteins. Two kinds of capsules were obtained: gel beads without membranes and gel beads with two membranes formed by the transacylation reaction. In vitro studies were carried out to determine the effects of simulated gastric pH and bile salts on the survival of free and encapsulated Bifidobacterium bifidum. The protective effects of gel beads without membranes and gel beads coated with two membranes formed by the transacylation reaction were evaluated. After 1 h in an acidic solution (pH 2.5), the free-cell counts decreased by 4.75 log units, compared with a <1-log decrease for entrapped cells. The free cells did not survive after 2 h of incubation at pH 2.5, while immobilized-cell counts decreased by about 2 log units. After incubation (1 or 3 h) in 2 and 4% bile salt solutions, the bifidobacterium mortality level for membrane-free gel beads (4 to 7 log units) was higher than that for free cells (2 to 3 log units). However, counts of bifidobacteria immobilized in membrane-coated gel beads decreased by <2 log units. Cell encapsulation in membrane-coated protein-polysaccharide gel beads could be used to increase the survival of healthy probiotic bacteria during their transit through the gastrointestinal tract.

Employment of stressful conditions during culture production to enhance subsequent cold- and acid-tolerance of bifidobacteria

AIMS

This study examined whether exposure of early stationary phase Bifidobacterium longum and B. lactis cells to various combinations of reduced temperature, reduced pH and starvation would enhance the cells' subsequent cold- and/or acid-tolerance.

METHODS AND RESULTS

Survival of B. longum in growth medium at 6 degrees C significantly (P < 0.05) increased as a result of starving cells for 30 or 60 min without any simultaneous decrease in temperature or pH. Acid-tolerance of B. lactis (at pH 3.5 in synthetic gastric fluid) increased significantly when the growth medium pH was decreased from 6.0 to 5.2 and cells experienced 30 or 60 min of starvation. Enhanced B. lactis acid-tolerance persisted through 8-11 weeks of -80 degrees C storage in the pH 5.2 growth medium. Upon addition to milk during yogurt manufacture, these cells initially had enhanced acid-tolerance relative to untreated cells but untreated cells became equally acid-tolerant during the first 2.5 h of yogurt manufacture.

CONCLUSIONS

The cold- and acid-tolerance of bifidobacteria vary widely, but may be significantly increased by application of sub-lethal stress to early stationary phase cells during culture production.

SIGNIFICANCE AND IMPACT OF THE STUDY

The enhancement of B. lactis acid-tolerance observed in this study may be of potential importance in the production of effective ready-to-consume probiotic dietary supplements.

Basic aspects and pharmacology of probiotics: an overview of pharmacokinetics, mechanisms of action and side-effects

Probiotics have been defined as non-pathogenic micro-organisms that, when ingested, exert a positive influence on host health or physiology. Their pharmacology is more complex than that of inert drugs but is now being studied in detail. Some strains have a high survival capacity until they reach the faeces, whereas others are rapidly killed by acid and bile (a characteristic that can be used for the delivery of active intracellular components). Potential translocation and permanent colonization are rare but possible events; and should come under closer scrutiny. Mechanisms of action can be direct or indirect through modifications of the endogenous flora or through immunomodulation. The active components are poorly known but include bacterial formylated peptides, peptidoglycan cell wall constituents and nucleotides. Although the safety of commercial probiotics is excellent, this aspect should be studied in more detail, especially in immunocompromised hosts.

Genetically engineered probiotics

Probiotic micro-organisms have been used for many years. Originating as food supplements, they are now most often administered orally and offer an attractive alternative for treating of intestinal disorders. A better understanding of the mechanisms by which these micro-organisms act has now opened up possibilities for designing new probiotic strains. Through genetic engineering, it is possible not only to strengthen the effects of existing strains, but also to create completely new probiotics. These need not necessarily be composed only of bacterial products but can also include elements of regulatory systems or enzymes derived from a foreign-human-source. If designed carefully and with absolute attention to biological safety in its broadest sense, the development of genetically modified probiotics has the potential to revolutionize alimentary health.