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PubMed1995

Short-chain fatty acids modulate growth of lactobacilli in mixed culture fermentations with propionibacteria.

Three strains of Lactobacillus (L. helveticus ATCC 15009 and CRL 581, and L casei LC 3) were paired with three strains of Propionibacterium (P. freudenreichii AP8, P. freudenreichii GP6 and P. acidipropionici CRL 756) and grown in individual and mixed cultures in a complex medium. Bacterial growth, carbohydrate consumption, and production of acids was determined and compared after mono and binary culture. Propionibacterium strains were inhibited in mixed cultures that rapidly reached low pH values, and stimulated in those with slow pH reduction. In several pairs Lactobacillus strains were stimulated by mixed cultivation, while in others they were unaffected or inhibited. Lactic acid reduction by Propionibacterium consumption was not always enough to produce a stimulatory effect on growth of lactobacilli. The behaviour of Lactobacillus strains in individual cultures in media with propionic acid was similar to that of mixed cultures with Propionibacterium. As propionic acid concentration increased in the medium and glucose was consumed, both individual and mixed cultures of lactobacilli showed inhibition of the growth and increase of the fermentation activity.

Fermentation↗
PubMed2004

Antagonistic activities of lactobacilli and bifidobacteria against microbial pathogens.

The gastrointestinal tract is a complex ecosystem that associates a resident microbiota and cells of various phenotypes lining the epithelial wall expressing complex metabolic activities. The resident microbiota in the digestive tract is a heterogeneous microbial ecosystem containing up to 1 x 10(14) colony-forming units (CFUs) of bacteria. The intestinal microbiota plays an important role in normal gut function and maintaining host health. The host is protected from attack by potentially harmful microbial microorganisms by the physical and chemical barriers created by the gastrointestinal epithelium. The cells lining the gastrointestinal epithelium and the resident microbiota are two partners that properly and/or synergistically function to promote an efficient host system of defence. The gastrointestinal cells that make up the epithelium, provide a physical barrier that protects the host against the unwanted intrusion of microorganisms into the gastrointestinal microbiota, and against the penetration of harmful microorganisms which usurp the cellular molecules and signalling pathways of the host to become pathogenic. One of the basic physiological functions of the resident microbiota is that it functions as a microbial barrier against microbial pathogens. The mechanisms by which the species of the microbiota exert this barrier effect remain largely to be determined. There is increasing evidence that lactobacilli and bifidobacteria, which inhabit the gastrointestinal microbiota, develop antimicrobial activities that participate in the host's gastrointestinal system of defence. The objective of this review is to analyze the in vitro and in vivo experimental and clinical studies in which the antimicrobial activities of selected lactobacilli and bifidobacteria strains have been documented.

Animals↗
PubMed2005

Screening of potential lactobacilli antigenotoxicity by microbial and mammalian cell-based tests.

Antigenotoxicity is considered an important property for probiotic lactobacilli. The ability of non probiotic lactobacilli from dairy products and starters to inhibit two reference genotoxins: 4-nitroquinoline-1-oxide and N-methyl-N'-nitro-N-nitrosoguanidine was evaluated. The study was carried out using short-term assays with different targets, such as procaryotic cells (SOS-Chromotest for genotoxicity in Escherichia coli and Ames test for mutagenicity in Salmonella typhimurium) and eucaryotic cells (Comet assay for genotoxicity in Caco-2 enterocytes). A high proportion of strains inhibiting 4-nitroquinoline-1-oxide activity was found in Lactobacillus casei, Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus delbrueckii subsp. bulgaricus and Lactobacillus plantarum. Inhibition of N-methyl-N'-nitro-N-nitrosoguanidine activity occurred in only one L. acidophilus strain. All the strains with antigenotoxic properties also demonstrated antimutagenic activity and produced modifications in genotoxin spectroscopic profiles. Strain viability during and after genotoxin exposure was confirmed. Concordance of the results obtained with microbial and mammalian cell-based tests is underlined.

4-Nitroquinoline-1-oxide↗
PubMed2005

Lactobacilli - bacteria-host interactions with special regard to the urogenital tract.

Lactobacilli are part of the commensal human mucosal flora. Their application as probiotics in dairy products such as yoghurt has increased during the last century since a health promoting effect has been reported. Much work has been done to study the effects of these bacteria on the immune system and epithelial cells, mainly focused on the intestinal mucosa as the field of first contact. This review is aimed to present and discuss results concerning interactions of lactobacilli and immune system or epithelial cells with focus to urogenital mucosa.

Animals↗
PubMed2005

Probiotic lactobacilli: an innovative tool to correct the malabsorption syndrome of vegetarians?

Vegetarians may have subtle nutritional deficiencies which have been related to the occurrence of an unrecognized malabsorption syndrome. The excess phytate content in cereals, nuts, legumes and oilseeds which represent the mainstay of their food intake, seems to play a central role in the pathogenesis of this malabsorption syndrome as an inverse relationship has been shown to link the phytate content of the diet with the intestinal absorption of trace minerals and proteins. We postulate that manipulating the endogenous digestive microflora of subjects on a vegetarian diet through administering probiotic lactic bacteria would represent an innovative tool to counteract the occurrence of the malabsorption syndrome dependent on the high phytate content of their diet. Even though there are no data about the composition of endogenous digestive microflora in subjects on a vegetarian diet, we expect that probiotic lactobacilli can interact with or affect distinct yet interrelated components within the intestinal milieu, such as epithelial cells, enteric flora, and/or mucosal immune cells. This would ultimately translate into the correction of the unregulated mechanisms implicated in the altered intestinal absorption of trace metals and proteins commonly seen in vegetarians. Clinical experience with probiotic therapy of patients with inflammatory bowel disease fully agrees with this view. One additional point of interest is that probiotic lactobacilli, and other species of the endogenous digestive microflora as well, are an important source of the enzyme phytase which catalyses the release of phosphate from phytate and hydrolyses the complexes formed by phytate and metal ions or other cations, rendering them more soluble ultimately improving and facilitating their intestinal absorption. The regular intake of probiotic preparation, may represent a cheap and safe tool in order to convert a diet with a low potential for bioavailability of trace minerals and proteins, such as the vegetarian diet, into a diet with a high bioavailability potential. The benefit of such an approach would not be restricted to vegetarians.

Diet, Vegetarian↗
PubMed2006

Selection of potential probiotic lactobacilli from pig feces to be used as additives in pelleted feeding.

Thirty-five isolates from pig feces were identified as Lactobacillus reuteri (12 strains), Lactobacillus mucosae (7), Lactobacillus plantarum (6), Lactobacillus kitasatonis (3), Lactobacillus rossiae (2), Lactobacillus ultunensis (2), Lactobacillus crispatus (2), and Lactobacillus intestinalis (1) by partial sequence analysis of the 16S rRNA. All isolates were detected at 8-9 log CFU g(-1). Preliminarily, strains were selected based on resistance to heat treatments (ca. 70 degrees C for 10 s). The decrease in viability for some L. reuteri, L. mucosae, L. plantarum, L. kitasatonis, and L. rossiae strains was lower than 1 log cycle. Selected strains were further characterized for acid and bile salt resistance, and antibacterial activity. Except for L. kitasatonis, tolerance to simulated gastric and intestinal conditions was enhanced for all strains by addition of reconstituted skimmed milk. Antibacterial activity was found against Gram-positive and -negative potential pathogens. L. reuteri 8.1, 3S7, 6.2, and 1.2, L. mucosae 1.1R, L. plantarum 4.1, and L. rossiae 4.4 were freeze-dried and mixed (1%, w/w) into pig feed before pelleting. After pelleting, pig feed contained 10-9 log CFU kg(-1) of lactobacilli. L. plantarum 4.1, and L. reuteri 3S7 were selected based on their bile salt resistance, pH tolerance, antimicrobial activity and heat resistance. The findings in this study provide a strong basis for exploring the potential of porcine lactobacilli isolates to be used in pelleted feeding as probiotic additives.

Animal Feed↗
PubMed2003

Efficacy of differently concentrated chlorhexidine varnishes in decreasing Mutans streptococci and lactobacilli counts.

The objective of the present prospective trial was to compare the efficacy of differently concentrated chlorhexidine varnishes (EC40) = 40% chlorhexidine and Cervitec = 1% chlorhexidine + 0.1% thymol) on levels of Mutans streptococci (ms), lactobacilli (lb) and plaque formation in interproximal plaque and saliva. Twenty-four volunteers with a high level of ms in saliva were randomized into two groups and treated with the experimental varnishes. Varnish applications were performed in accordance with literature. Over a period of 2 weeks Cervitec was applied three times and EC40 once or twice, depending on ms counts after first application. Four and 12 weeks after final varnish application ms in plaque and saliva were evaluated. Furthermore, lactobacilli (lb) counts in saliva and the effect on plaque formation were recorded. Both varnishes revealed a reduction of ms in interproximal plaque and saliva after 4 and 12 weeks. The highly concentrated varnish revealed a significantly stronger reduction of ms in plaque and saliva compared with the lowly-concentrated varnish. No effect could be demonstrated on lb counts and plaque formation. The results indicate that the chlorhexidine varnishes tested may reduce ms in both interproximal plaque and saliva. However, the application of the highly concentrated varnish EC40 results in a higher decrease of ms in plaque sites and saliva.

Adult↗
PubMed1999

A rapid and safe plasmid isolation method for efficient engineering of recombinant lactobacilli expressing immunogenic or tolerogenic epitopes for oral administration.

Recombinant lactobacilli are being developed which can be used as expression and delivery vectors of heterologous antigens in oral vaccination and other therapeutic applications. Because most Lactobacillus strains do not accept ligation mixtures, sufficiently pure plasmid DNA needs to be isolated from Lactobacillus casei to transform other Lactobacillus strains. The isolation of plasmid DNA from Gram-positive lactobacilli is complicated by the resilience of the peptidoglycan layer. Here a rapid, safe and efficient method is described that combines enzymatic breakdown of the cell wall and purification of the plasmid by commercially available DNA-binding columns. For the lysis-resistant L. casei strain, this method yields high levels of pure plasmid DNA that can be used for common molecular techniques, such as digestion and transformation, with high efficiency.

Administration, Oral↗
PubMed2002

Comparison of two selective media for the detection and enumeration of Lactobacilli in human faeces.

The enumeration of faecal bacteria is an important requirement for many studies of bowel health. One approach is the use of selective culture media for the culture and identification of genera or species from faeces. This study compares the culture of Lactobacilli from dilution series of faecal samples from six healthy human volunteers on two commonly used media, LAMVAB and Rogosa agar. Colonies were counted after a 72-h anaerobic incubation at 37 degrees C, and colony morphology recorded by a single observer. DNA was isolated from a representative number of colonies and genus-specific PCR, single-stranded conformation polymorphism (SSCP) and DNA sequencing performed. Total colony counts ranged from <3.00 to 7.48 log(10) cfu/g of faeces for LAMVAB and 5.09 to 7.66 log(10) cfu/g for Rogosa. For each subject, the total colony count was higher on Rogosa than that obtained with LAMVAB agar. SSCP analysis and DNA sequencing indicated that colony morphology was not an accurate predictor of genus identity. Growth of two species, Lactobacillus acidophilus and Lactobacillus gasseri, was not supported on LAMVAB medium. Rogosa agar was more likely to support growth of non-Lactobacillus species. Therefore, neither medium gave a fully accurate representation of the Lactobacilli species present in human faecal samples.

Adult↗
PubMed1989

Occurrence of conjugative amylolytic activity in rumen lactobacilli.

1,263 rumen strains of Lactobacilli were selected for the production of amylase and resistance to antibiotics. Out of 48 amylolytic Lactobacilli, in 17 strains, there was a cotransfer of the alpha amylase activity and resistance to tetracyclin with a transfer frequency of 10(-3) to 10(-7) ml-1 of the conjugative mixture. In strains No. 30, No. 36 and No. 49, plasmids with similar molecular weights as plasmids in corresponding transconjugants were detected. Similar protein pattern of the donors recipient of the L. lactis RN 1 and transconjugants obtained by PAGE proved the cotransfer of the amylase activity and antibiotic resistance.

Amylases↗
PubMed2003

Mutans streptococci and lactobacilli in carious dentine before and after Atraumatic Restorative Treatment.

OBJECTIVES: This study was performed to examine the cultivable flora in dentine after manual excavation of caries lesions using the Atraumatic Restorative Treatment (ART) technique and to examine for associations between the microbiological results and cavity size, dentine colour and consistency. METHODS: Dentine samples from 40 caries lesions were collected before and after treatment and cultured for total viable counts (TVC), mutans streptococci (MS) and lactobacilli. RESULTS: The bacterial bioburden between the two samples showed a significant reduction in the frequency and proportions of TVC and MS but not lactobacilli. CONCLUSION: Cavity preparation produced a clinical change in dentine colour and consistency from dark shades and soft dentine at enamel dentine junction to light shades and hard dentine at the cavity floor. The results show that cavity size, dentine colour and consistency are not absolute indicators of the microbiological bioburden in an ART cavity.

Child↗
PubMed1998

Molecular identification and cluster analysis of homofermentative thermophilic lactobacilli isolated from dairy products.

Twenty-five strains of thermophilic lactobacilli isolated from yoghurt and from semi-hard and hard cheeses (in parallel with nine type or reference strains) were identified and grouped according to their genetic relatedness. Strains were identified by sugar fermentation patterns using the "API 50 CHL" galleries, by species-specific DNA probes in dot-blot hybridization experiments, by amplification and restriction analysis of the 16S rRNA gene (ARDRA) and by polymerase chain reaction (PCR) using species-specific oligonucleotide primers. Strains were classified as Lactobacillus delbrueckii subsp. lactis and subsp. bulgaricus, L. helveticus, and L. acidophilus. Strains which were atypical by sugar fermentation patterns were also identified. Most of the strains could not be grouped using carbohydrate fermentation profiles. PCR fingerprinting was used to identify DNA profiles for the 25 lactobacilli. Experimentally obtained PCR profiles enabled discrimination of all strains, which were grouped according to the similarities in their combined patterns. In general, the clustering of the strains corresponded well with species delineation obtained by molecular identification. The dendrogram of genetic relatedness enabled the unambiguous identification of most of the strains which were shown to be atypical by the sugar fermentation profile, except for a discrepancy in one L. delbrueckii subsp. lactis strain and one atypical Lactobacillus sp. strain.

Bacterial Typing Techniques↗
PubMed2000

Technological and biological evaluation of tablets containing different strains of lactobacilli for vaginal administration.

Ten strains of lactobacilli were evaluated for the administration of viable microorganisms to restore the normal indigenous flora in the treatment of urogenital tract infections (UTI) in women. As the strains considered are facultative anaerobes, optimization of the production process was particularly critical to preserve bacterial viability. The microorganisms were formulated in single- and double-layer vaginal tablets. The two layers were characterized by different release properties: one is an effervescent composition that ensures a rapid and complete distribution of the active ingredient over the whole vaginal surface; while the second is a sustained release composition capable of releasing the lactobacilli over a longer period of time. Three different retarding polymers were tested, and all the formulations and tablets were evaluated in terms of technological processability, bacterial viability and stability, and cell adhesion properties of the microorganisms. From the results obtained, three out of ten strains appear particularly suitable for their application in the treatment of UTI. A larger batch of tablets made with a mixture of the three strains was then evaluated, confirming the feasibility of their industrial production and a good bacterial viability in the final dosage form.

Administration, Intravaginal↗
PubMed1997

Five-year follow-up study of saliva, mutans streptococci, lactobacilli and yeast counts in lymphoma patients.

Twenty-two patients out of the 79 that were originally included were examined 5 years after beginning anticancer therapy for lymphomas. The patients' cumulative data on salivary flow rate, buffering capacity and acidogenic microbial counts were compared with respective data of 17 patients who died during the follow-up. Stimulated saliva samples had been taken at baseline and during the cytostatic treatment with combination chemotherapy, and 1 year and 5 years later. Chair-side kits were used at the hospital ward for the assessment of the study parameters. Mean saliva flow at baseline was 1.5 +/- 0.7 ml/min in the surviving group and 1.5 +/- 0.8 ml/min in the deceased. Salivary flow rates were not affected by the anticancer treatment and there was no statistically significant difference between the groups in this respect. A significant difference was observed between the groups in salivary buffering capacity values at baseline: only 32% of the survived had low buffering capacity in comparison to 69% of those who later died (P < 0.02). Buffering capacity values remained low in 50% of the surviving patients 5 years later. Higher mutans streptococci and lactobacilli counts were seen among the deceased than in the survived patients but mutans streptococci decreased significantly in both groups after the start of the anticancer therapy (P < 0.05). The number of positive yeast counts increased consistently during the chemotherapy in both groups, being higher in the survived when compared with the deceased patients. Yeast counts remained positive 5 years later in 73% of the survived patients, while the mean mutans streptococci and lactobacilli counts decreased below baseline values. The results showed that persistently high salivary microbial counts and low buffering capacity may be linked with poor prognosis.

Adult↗
PubMed2005

Vaginal lactobacilli, probiotics, and IVF.

Perturbation of the normal lactobacilli-dominated vaginal microflora is associated with reproductive failure and adverse pregnancy outcomes, ranging from early pregnancy loss to late miscarriage and preterm birth. As high rates of bacterial vaginosis are observed with IVF patients, abnormal vaginal microflora presumably explain, at least to some extent, reproductive failure as well as the increased risk of adverse pregnancy outcome seen in these patients. Accordingly, there may be a window of opportunity for improving IVF success rates and outcomes. At present, a screen-and-treat procedure to restore the normal vaginal microflora is not a routine part of the infertility work-up and treatment. While Gram staining of vaginal smears would offer an inexpensive and validated means for screening and diagnosis, probiotics that contain live lactobacilli capable of re-colonizing the vagina may offer an elegant and safe choice of treatment. Carefully designed trials using well characterized probiotic strains and treatment regimens are still required to evaluate the effect of probiotics on IVF-embryo transfer pregnancy rates.

Female↗
PubMed2004

In vitro screening of potential probiotic activities of selected lactobacilli isolated from unpasteurized milk products for incorporation into soft cheese.

The aim was to select potentially probiotic lactobacilli from 88 strains isolated from unpasteurized milk and cheese products, and to incorporate these bacteria in a viable state into a soft cheese, without changing its quality. The survival of these bacteria was assessed in acidic and bile conditions, after freezing at -80 degrees C. Four strains from unpasteurized Camembert--two Lactobacillus plantarum strains and two Lb. paracasei/casei strains--were identified and typed by PCR and PFGE and were found to display potentially probiotic characteristics in addition to resistance to low pH and bile. These characteristics were resistance to lysozyme, adhesion to CACO-2 cells, antimicrobial effects against common foodborne pathogens (Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., Escherichia coli, innocuity following the ingestion of high doses by mice and appropriate antibiotic susceptibility profiles. The potential of Lb. plantarum strain UCMA 3037 for incorporation into a soft cheese (Pont-l'Eveque registered designation of origin (RDO)) was investigated. This strain grew well and survived in sufficient numbers (more than 10(7) cfu/g throughout the shelf-life of the product) in the cheese. This strain did not change the quality score of the product until the best before date (75 days after manufacture). Thus, unpasteurized Camembert is a natural source of potentially probiotic lactobacilli, which could be used as an additive in the development of potentially probiotic soft cheeses. Further work is required to demonstrate the persistence and efficacy of these strains in the human host upon ingestion.

Animals↗
PubMed2002

Development and potential of starter lactobacilli resulting from exploration of the sourdough ecosystem.

Lactic acid bacteria are widely used as starter organisms in food fermentations. The development of such cultures as organisms fulfilling all metabolic, technical and handling requirements is the result of a multidisciplinary approach, i.e. to analyse, follow and direct the microbial ecology in food fermentations by molecular biology tools, gene cloning, biochemical and physiological analyses, pilot trials and modelling of behaviour and metabolism. The possibilities and restrictions of such an approach is given for cereal fermentations, namely sourdoughs. In this environment highly adapted lactobacilli are predominant, sharing the environment with yeasts present in traditional preparations. The competitiveness of these lactobacilli and their contribution to flavour, machineability and prebiosis of doughs and bread relies on their maltose and amino acid metabolism, use of electron acceptors and EPS formation. Their reactions on environmental stresses can be used to embed these recalcitrant organisms into starter culture preparations. Beyond the cereal environment the described strategy can be generally applied to understand ecosystems in food fermentations and finally control them.

Bread↗
PubMed2000

Engineering the microflora to vaccinate the mucosa: serum immunoglobulin G responses and activated draining cervical lymph nodes following mucosal application of tetanus toxin fragment C-expressing lactobacilli.

The delivery of antigens to mucosal-associated lymphoid tissues in paediatric and immunocompromised populations by safe, non-invasive vectors, such as commensal lactobacilli, represents a crucial improvement to prevailing vaccination options. In this report, we describe the oral and nasal immunization of mice with vaccines constructed through an original system for heterologous gene expression in Lactobacillus in which the 50 000-molecular weight (MW) fragment C of tetanus toxin (TTFC) is expressed either as an intracellular or a surface-exposed protein. Our data indicate that L. plantarum is more effective in this respect than L. casei and that, under the experimental conditions investigated, delivery of TTFC expressed as an intracellular antigen is more effective than cell-surface expression. Immunization of mice with live recombinant lactobacilli induced significant levels of circulating TTFC-specific immunoglobulin G (IgG) following nasal or oral delivery of vaccine strains. In addition, following nasal delivery, secretory immunoglobulin A (sIgA) was induced in bronchoalveolar lavage fluids, as were antigen-specific antibody-secreting cells and antigen-specific T-cell activation in draining lymph nodes, substantiating their potential for safe mucosal delivery of paediatric vaccines.

Animals↗