Lactobacillus Murinus Research Articles

Microbiota: A high-pressure situation for bacteria.

Analyses in mice suggest that dietary salt increases blood pressure partly by affecting some of the microbes that inhabit the gut. The implications of this work for hypertension warrant further study in humans. See Article p.585 The role of the gut microbiota in human disease is becoming increasingly recognized. In this study, Dominik Muller and colleagues report that a diet high in salt alters the composition of the gut microbiota in mice, causing pronounced depletion of the commensal Lactobacillus murinus and reduced production of indole metabolites. Previous work has suggested that a high salt diet leads to the generation of pathogenic T helper 17 (TH17) cells, which have been linked to hypertension and autoimmunity. The authors show that treatment of mice on a high salt diet with L. murinus prevents salt-induced aggravation of actively induced autoimmune encephalomyelitis and salt-sensitive hypertension, through the suppression of TH17 cells. In a pilot study in a small number of humans, the authors also show that high-salt challenge induces an increase in blood pressure and TH17 cells, associated with a reduction in Lactobacillus in the gut. However, future work is required to determine whether the findings for mice are translatable to humans.

Salt-responsive gut commensal modulates TH17 axis and disease.

Western lifestyle with high salt consumption leads to hypertension and cardiovascular disease. High salt may additionally drive autoimmunity by inducing T helper (TH)17 cells, which may also contribute to hypertension. Induction of TH17 cells depends on the gut microbiota, yet the effect of salt on the gut microbiome is unknown. In mouse model systems, we show that high salt intake affects the gut microbiome, particularly by depleting Lactobacillus murinus. Consequently, L. murinus treatment prevents salt-induced aggravation of actively-induced experimental autoimmune encephalomyelitis and salt-sensitive hypertension, by modulating TH17 cells. In line with these findings, moderate high salt challenge in a pilot study in humans reduces intestinal survival of Lactobacillus spp. along with increased TH17 cells and blood pressure. Our results connect high salt intake to the gut-immune axis and highlight the gut microbiome as a potential therapeutic target to counteract salt-sensitive conditions.

β-Glucans in food modify colonic microflora by inducing antimicrobial protein, calprotectin, in a Dectin-1-induced-IL-17F-dependent manner.

Dectin-1 (gene symbol: Clec7a) is a receptor for β-glucans that play an important role for the host defense against fungi. Recently, we showed that Clec7a-/- mice are resistant against dextran sodium sulfate (DSS)-induced colitis because of regulatory T-cell population expansion in the colon. The regulatory T-cell expansion is caused by expansion of commensal Lactobacillus murinus whose growth is suppressed by an antimicrobial protein, calprotectin S100A8/A9. In this report, we showed that S100A8 was mainly produced by mouse colonic epithelial cells. S100A8 was not induced directly by Dectin-1 but by Dectin-1-induced cytokines, especially interleukin-17F (IL-17F), that were produced by several types of innate immune cells including CD11c+/CD11b+ myeloid cells in colonic lamina propria. S100A8/A9 heterodimer preferentially suppressed the growth of L. murinus that was increased in both Clec7a-/- and Il17f-/- mice. Furthermore, similar expansion of L. murinus and DSS-colitis resistance were observed in mice fed with β-glucan-free food. These observations suggest that food-derived β-glucans control the specific commensal microbiota via the Dectin-1-IL-17F-calprotectin axis to maintain the intestinal homeostasis.

Intestinal Dysbiosis and Biotin Deprivation Induce Alopecia through Overgrowth of Lactobacillus murinus in Mice

Metabolism by the gut microbiota affects host physiology beyond the gastrointestinal tract. Here, we findthat antibiotic-induced dysbiosis, in particular, overgrowth of Lactobacillus murinus (L.murinus), impaired gut metabolic function and led to the development of alopecia. While deprivation of dietary biotin per se did not affect skin physiology, its simultaneous treatment with vancomycin resulted in hair loss in specific pathogen-free (SPF) mice. Vancomycin treatment induced the accumulation of L.murinus in the gut, which consumes residual biotin and depletes available biotin in the gut. Consistently, L.murinus induced alopecia when monocolonized in germ-free mice fed a biotin-deficient diet. Supplementation of biotin can reverse established alopecia symptoms in the SPF condition, indicating that L.murinus plays a central role in the induction of hair loss via a biotin-dependent manner. Collectively, our results indicate that luminal metabolic alterations associated with gut dysbiosis and dietary modifications can compromise skin physiology.

MICROENCAPSULATION OF INDIGENOUS POULTRY LACTIC ACID BACTERIA PROBIOTIC ON THE COMPETITIVE EXCLUSION AGAINST Salmonella enteritidis AND Escherichia coli IN VITRO

This study was conducted to investigate the effect of microencapsulation of lactic acid bacteria (LAB) probiotic isolated from chickens’ gastrointestinal tract on Salmonella enterica serotype enteritidis ATCC 13076 and Escherichia coli EPEC. Probiotic of LAB used were Streptococcus thermophilus strain Kp-2, Lactobacillus murinus strain Ar-3, and Pediococcus acidilactici strain Kd-6. Microencapsulation were conducted by spray drying with inlet/outlet temperatures of 160/80°C using maltodextrin and skim milk powder (20% w/v) as coating materials. Competitive exclusion test was conducted in vitro using well diffusion method. Variable measured in this study was the clear zone observed. The data of clear zone among treatments were analyzed using analysis of variance (ANOVA) one way followed by Duncan multiple range test (DMRT); except the data of clear zone resulted by probiotic before and after microencapsulation that was analyzed using t-test. The result showed that the ability of each strain against pathogen was decreased after being encapsulated. S. thermophilus before and after microencapsulation had the same antagonistic ability against E. coli and S. enteritidis (P>0.05). Microencapsulation process with spray drying method decreased antagonistic ability of probiotic against pathogenic bacteria both in single and multi strain.

Draft Genome Sequence of the Murine Bacterial Isolate Lactobacillus murinus EF-1.

ABSTRACT Screening for lysogenic lactobacilli in rat fecal samples has identified Lactobacillus murinus EF-1. Whole-genome sequencing revealed a 2.30-Mb draft genome with 39.6% G+C content and 2,196 open reading frames. PHAST analysis identified three intact prophages of 26.1 kb, 25.4 kb, and 49.6 kb in size.

Potential application of genetically identical somatic cell nuclear transfer-cloned dogs for gastrointestinal microbiota analysis

This study investigated the gastrointestinal microbiota in three genetically identical cloned dogs (A, B and C) by somatic cell nuclear transfer. We collected feces from three cloned dogs and their feed to investigate gastrointestinal microbiota using both culture-dependent and culture-independent methods. A total of 962 strains from the feces of cloned dogs were isolated using aerobic and anaerobic culture methods. The dominant microorganisms were Enterococcus faecalis and Enterococcus faecium in all fecal samples. In particular, the fecal sample from cloned dog C had similar proportions of three species (E. faecalis, E. faecium and Lactobacillus murinus). In all, 29 DNA fragments were identified by PCR-denaturing gradient gel electrophoresis (DGGE) analysis. The highest DGGE band intensities were for E. faecalis from cloned dogs A and C and for Clostridium sordellii from cloned dog B, with relative intensities of 15.2, 17.7 and 14.4%, respectively. The other strains identified from the cloned dogs were Chryseobacterium soldanellicola, Escherichia coli, L. murinus, Streptococcus alactolyticus, Weissella confusa and uncultured bacterium. Some microbes isolated from the fecal samples, including C. soldanellicola and W. confuse, were derived from the feed. Overall, gastrointestinal microbiota of all genetically identical cloned dogs, maintained under the same environmental and feeding conditions, showed similar profiles in terms of species diversity analyzed by PCR-DGGE, although there were proportional differences in the amounts of bacterial species. To our knowledge, this is the first report to investigate and compare gastrointestinal microbiota of three genetically identical dogs.

Pengaruh Suplementasi Probiotik Bakteri Asam Laktat Terhadap Histomorfologi Usus Dan Performan Puyuh Jantan

The present study was conducted to investigate the effects of lactic acid bacteria (LAB ) probiotic s supplementation on intestinal histomorpholgy and performance of male quail. The LAB probiotics supplement contained of three strains, those are Lactobacillus murinus, Streptococcus thermophilus, and Pediococcus acidilactici. A total of 96 day-old male quails (DOQ) were randomly divided into four groups of LAB probiotic supplementation r eared for 42 days . O ral supplementation of LAB probiotic were 0 (P0) , 10 7 (P1) , 10 8 (P2) , and 10 9 (P3) CFU/mL/bird/day. Data were analyzed by analysis of variance CRD One-Way Anova continued with Duncan’s New Multiple Range Test (DMRT) . The results showed that LAB probiotic treatment a ffect ed on the intestinal morphology, body weight gain , and feed conversion of male quail (P <0.05). Height of intestinal villi were 288.45±8.18 , 322.72±1.84 , 324.82±2.06 , and 390.80±13.24 (µm) respectively. Width of intestinal villi were 112.82±2.35 , 138.62±2.35 , 162.57±17.15 and 130.72±13.45 (µm) respectively. Depth of intestinal crypts were 61.25±1.49 , 72.50±6.25 , 69.85±4.55 , and 69.05±4.57 (µm) respectively . Feed intake were not different, but resulted difference body weight gain, which wer e 102.85±4.72 , 109.20±4.13 , 115.07±7.61 , and 118.75±2.54 ( g ), respectively . Feed conversion were 4.30±0.43 , 4.26±0.17 , 3.91±0.30 , and 3.79±0.27 , respectively. This study indicated that supplementation of 10 9 CFU / m L / bird /day of LAB probiotic s showed the best result.

ID: 135: Inhibition of Dectin-1 signaling ameliorates colitis by inducing Lactobacillus-mediated regulatory T cell expansion in the intestine

Dectin-1, the receptor for beta-glucans, protects host from fungal infection. However, the role of Dectin-1 in intestinal immunity has not been elucidated completely. We found that Dectin-1-deficient (Clec7a−/−) mice were refractory to both dextran sodium sulfate (DSS)- and CD45RBhiCD4+ T cell-induced colitis associated with an increase of regulatory T (Treg) cells. The proportion of lactobacilli, especially Lactobacillus murinus (L. murinus), in commensal microflora was increased in Clec7a−/− mouse colon due to accompanied by a decrease of a group of antimicrobial peptides induced by Dectin-1 signaling. L. murinus colonization increased Treg cells in the colon. Oral administration of laminarin, a Dectin-1 antagonist, suppressed the development of DSS-colitis, associated with the increase of L. murinus and Treg cells. The proportion of closely related Lactobacillus species was decreased in inflammatory bowel disease patients. These observations suggest that Dectin-1 regulates the homeostasis of intestinal immunity by controlling Treg cell differentiation through modification of microbiota.

Inhibition of Dectin-1 Signaling Ameliorates Colitis by Inducing Lactobacillus-Mediated Regulatory T Cell Expansion in the Intestine.

Dectin-1, the receptor for β-glucans, protects the host against fungal infection; however, its role in intestinal immunity is incompletely understood. We found that Dectin-1-deficient (Clec7a(-/-)) mice were refractory to both dextran sodium sulfate (DSS)- and CD45RB(high)CD4(+) T cell-induced colitis, and that this resistance was associated with an increase in regulatory T (Treg) cells. The proportion of lactobacilli, especially Lactobacillus murinus, in the commensal microflora was increased in Clec7a(-/-) mouse colons, and accompanied by a decrease in antimicrobial peptides induced by Dectin-1 signaling. L. murinus colonization increased Treg cells in the colon. Oral administration of laminarin, a Dectin-1 antagonist, suppressed the development of DSS-colitis, associated with an increase of L. murinus and Treg cells. Human patients with inflammatory bowel disease were found to have a decreased proportion of closely related Lactobacillus species. These observations suggest that Dectin-1 regulates the homeostasis of intestinal immunity by controlling Treg cell differentiation through modification of microbiota.

Effect of MDG-1, a polysaccharide from Ophiopogon japonicas, on diversity of lactobacillus in diet-induced obese mice

For understanding the effect of MDG-1, a water-soluble β-D-fructan polysaccharide from Ophiopogon japonicas, on intestinal microecological balance, especially on the changes of lactobacillus, sixty 8-week-old male C57BL/6J mice were given a high-fat diet for six weeks and were also gavaged with saline once a day simultaneously. Then the mice which is below 30 grams or dropped more than 10% through lavage were eliminated and the rest were randomly divided into four groups: diet-induced obese (DIO) model group (n = 12, gavaged with saline), low-dose MDG-1 group (n = 12, gavaged with MDG-1, 75 mg · kg(-1)) , medial-dose MDG- 1 group (n = 12, gavaged with 150 mg · kg(-1)), and high-dose MDG-1 group (n = 12, gavaged with 300 mg · kg(-1)) according to the weight and blood glucose; the model group and MDG-1 group were placed on a high-fat diet while the normal control group (n = 12, gavaged with saline) were kept on a low-fat diet through the experiment. After 12-weeks of treatment, feces samples were collected and cultured for intestinal microecological balance analysis. Then the intestinal probiotics were cultured through traditional methods combined with modified gradient gel electrophoresis (DGGE) method. The changes of lactobacillus in each treatment group were also detected by a statistical analysis of the total number of the intestinal flora. We have established the phylogenetic tree by 16S rDNA sequencing and use some molecular identification methods such as PCR-DGGE to analyse the changes of the dominant bacteria floras, and also get the pure culture. In conclusion, different concentrations of MDG-1 can increase the number of the intestinal probiotics, especially Taiwan lactobacillus and Lactobacillus murinus, and improve their diversity and promote proliferation in a dose-dependent way.

Bile tolerance and its effect on antibiotic susceptibility of probiotic Lactobacillus candidates.

Before use in practice, it is necessary to precisely identify and characterize a new probiotic candidate. Eight animal lactobacilli and collection strain Lactobacillus reuteri CCM 3625 were studied from the point of saccharide fermentation profiles, bile salt resistance, antibiogram profiles, and influence of bile on sensitivity to antibiotics. Studied lactobacilli differed in their sugar fermentation ability determined by API 50CHL and their identification based on these profiles did not correspond with molecular-biological one in most cases. Survival of strains Lactobacillus murinus C and L. reuteri KO4b was not affected by presence of bile. The resistance of genus Lactobacillus to vancomycin and quinolones (ofloxacin, ciprofloxacin) was confirmed in all strains tested. This study provides the new information about oxgall (0.5 and 1 %) effect on the lactobacilli antibiotic susceptibility. Antibiotic profiles were not noticeably affected, and both bile concentrations tested had comparable impact on the lactobacilli antibiotic sensitivity. Interesting change was noticed in L. murinus C, where the resistance to cephalosporins was reverted to susceptibility. Similarly, susceptibility of L. reuteri E to ceftazidime arose after incubation in both concentration of bile. After influence of 1 % bile, Lactobacillus mucosae D lost its resistance to gentamicin. On the base of gained outcomes, the best probiotic properties manifested L. reuteri KO4b, Lactobacillus plantarum KG4, and L. reuteri E due to their survival in the presence of bile.

Analysis of the microbial ecology between Helicobacter pylori and the gastric microbiota of Mongolian gerbils

Animal models are essential for in vivo analysis of Helicobacter-related diseases. Mongolian gerbils are used frequently to study Helicobacter pylori-induced gastritis and its consequences. The presence of some gastric microbiota with a suppressive effect on H. pylori suggests inhibitory gastric bacteria against H. pylori infection. The aim of the present study was to analyse the microbial ecology between H. pylori and the gastric microbiota of Mongolian gerbils. Gastric mucosa samples of H. pylori-negative and -positive gerbils were orally inoculated to five (Group 1) and six (Group 2) gerbils, respectively, and the gerbils were challenged with H. pylori infection. The colonization rate (40 %) of H. pylori in Group 1 gerbils was lower than the rate (67 %) in Group 2 gerbils. Culture filtrate of the gastric mucosa samples of Group 1 gerbils inhibited the in vitro growth of H. pylori. Three lactobacilli species, Lactobacillus reuteri, Lactobacillus johnsonii and Lactobacillus murinus, were isolated by anaerobic culture from the gerbils in Groups 1 and 2, and identified by genomic sequencing. It was demonstrated that the three different strains of lactobacilli exhibited an inhibitory effect on the in vitro growth of H. pylori. The results suggested that lactobacilli are the dominant gastric microbiota of Mongolian gerbils and the three lactobacilli isolated from the gastric mucosa samples with an inhibitory effect on H. pylori might have an anti-infective effect against H. pylori.

In vitro evaluation method for screening of candidate prebiotic foods

The aim of this work was to develop a simple and rapid in vitro evaluation method for screening and discovery of uncharacterised and untapped prebiotic foods. Using a NMR-based metabolomic approach coupled with multivariate statistical analysis, the metabolic profiles generated by intestinal microbiota after in vitro incubation with feces were examined. The viscous substances of Japanese bunching onion (JBOVS) were identified as one of the candidate prebiotic foods by this in vitro screening method. The JBOVS were primarily composed of sugar components, especially fructose-based carbohydrates. Our results suggested that ingestion of JBOVS contributed to lactate and acetate production by the intestinal microbiota, and were accompanied by an increase in the Lactobacillus murinus and Bacteroidetes sp. populations in the intestine and fluctuation of the host-microbial co-metabolic process. Therefore, our approach should be useful as a rapid and simple screening tool for potential prebiotic foods.

In vitro evaluation of the safety and probiotic properties of Lactobacilli isolated from chicken and calves

A total of 73 chicken and calves isolates were diagnosed using matrix-assisted laser desorption ionization-time-of flight mass spectrometry (Maldi-Tof MS). After a preliminary subtractive screening based on the high acid tolerance at pH 2.5 and bile resistance at 0.3% oxgall, twenty isolates belonging to the species Lactobacillus salivarius, Lactobacillus agilis, Lactobacillus reuteri, Lactobacillus murinus and Lactobacillus amylovorus were in vitro screened for the safety assessment and probiotic properties, including antibiotics susceptibility patterns, biochemical activity and potential for competitive exclusion of biofilm producing pathogens determined by crystal violet and/or quantitative Fluorescent in situ Hybridisation (FISH) assays utilizing 5′Cy 3 labelled probe Enter1432 for enteric group.Antibiotic susceptibility testing was performed according to the ISO norm 10932. The sixteen strains were susceptible to certain antimicrobial agents, except for two chicken (L. salivarius 12K, L. agilis 13K) and two calves (L. reuteri L10/1, L. murinus L9) isolates with the presence non wild-type ECOFFs (epidemiological cut-off) for gentamicin (≥256 μg ml−1), tetracycline (≥128 μg ml−1), kanamycin (≥256 μg ml−1) and streptomycin (≥96 μg ml−1). The two referenced chicken isolates gave positive aac(6′)Ie-aph(2″)Ia and tet(L) PCR results.The wild-type ECOFFs isolates were subjected to the apiZYM analysis for enzyme profile evaluation and amino acid decarboxylase activities determined by qualitative plate method and multiplex PCR for the detection of four genes involved in the production of histamine (histidine decarboxylase, hdc), tyramine (tyrosine decarboxylase, tyrdc) and putrescine (via eithers ornithine decarboxylase, odc, or agmatine deiminase, agdi). From examined strains only two chicken isolates (L. reuteri 14K; L. salivarius 15K) had no harmful β-glucuronidase, β-glucosidase activities connected with detrimental effects in the gastrointestinal tract and together no amino acid decarboxylase activities and no genes associated with biogenic amines production though only chicken L. salivarius 15K whole cells and acid supernatants shown strong suppressive potential against biofilm-forming Klebsiella and Escherichia coli. Our results highlight that above-mentioned isolate L. salivarius 15K fulfils the principle requirements of a qualified probiotic and may be seen as a reliable candidate for further validation studies in chicken.

Isolation and characterization of faecal bifidobacteria and lactobacilli isolated from dogs and primates

Although bifidobacteria and lactobacilli have been suggested beneficial for the host and are components of many probiotics and competitive exclusion mixtures, the knowledge on abundance, metabolic and probiotic characteristics in isolates from dogs and monkeys is still limited. The present study was aimed to isolate Bifidobacterium and Lactobacillus strains (faeces of 22 dogs and of 5 primates: Cebus apella, Eulemur fulvus, Erythrocebus patas, Macaca fascicularis, Papio hamadryas) with the MALDI-TOF identification system Lactobacillus murinus, Bifidobacterium animalis and Pediococcus acidilactici were more frequently isolated species in dogs while Lactobacillus plantarum was isolated in several species of primates. Ten strains of 6 species were assayed for enzymatic activities (only Lactobacillus reuteri strains showed no undesirable enzymatic activity), antimicrobial susceptibility (detected higher minimum inhibitory concentration levels for tetracycline and gentamicin), and inhibitory activity against 15 indicator bacteria. All strains inhibited Gram-negative indicators while lactobacilli showed larger inhibition zones than bifidobacteria. L. reuteri II/3b/a (isolate from M. fascicularis) showed the best antimicrobial properties. Resistance to bile (0.3% w/v) was observed in all tested strains (no decrease of CFU/ml) whereas the decrease of 68.4–94.4% (after 90 min exposition) and 78.4–99.9% CFU/ml (after 180 min) depending on the strain was detected in the artificial gastric juice.

Enhanced expression of fucosyl GA1 in the digestive tract of immune-deficient scid, nude and pIgR(-/-) mice

Fucosylation of GA1 in murine intestinal epithelia occurs through transcriptional induction of α1,2-fucosyltransferase along with bacterial infection, but the mechanism has not been clearly characterized as to whether it is induced as a result of an immune response to bacteria or of genetic manipulation of the host by bacteria. Accordingly, we analysed the expression of fucosyl GA1 (FGA1) and fucosyltransferase activity in the digestive tracts of immune-deficient scid, nude and pIgR(-/-) mice. In comparison with those in control mice bred under the same SPF circumstances, the amount of FGA1 and the α1,2-fucosyltransferase activity were significantly increased in the immune-deficient mice, indicating that the immune system is not involved in induction of the α1,2-fucosyltransferase gene. Reflecting the enhanced synthesis of FGA1, the total amounts of FGA1 in the intestinal contents of immune-deficient mice were higher than those in control mice. Also, the major faecal bacteria grown on a MRS agar plate were different in immune-deficient and control mice as follows, Lactobacillus murinus for scid and pIgR(-/-) mice, and Lactobacillus johnsonii for their control, and Enterococcus faecalis for nude mice and Lactococcus garvieae for the control, indicating that an alteration in the intestinal lactobacilli is partly involved in the induction of α1,2-fucosyltransferase.

In vitro assessment of functional properties of lactic acid bacteria isolated from faecal microbiota of healthy dogs for potential use as probiotics

Lactic acid bacteria were isolated and identified in the faeces of Chinese Crested and Yorkshire terrier pups and their probiotic features were investigated in vitro. Thirty seven isolates were identified as Lactobacillus or Enterococcus. Out of these isolates, 31 were lactic acid bacteria (LAB) and belonged to the species Lactobacillus reuteri (16/37; 43.3%), Lactobacillus animalis (7/37; 18.9%), Lactobacillus acidophilus (3/37; 8.1%), Lactobacillus sanfranciscensis (2/37; 5.4%), Lactobacillus murinus (2/37; 5.4%), and Lactobacillus paraplantarum (1/37; 2.7%), while six other LAB isolates were Enterococcus spp. (6/37; 16.2%). Strains were tested for resistance to gastric acidity (pH 2.5 for 3 h) and bile salts (0.3% ox gall), cell surface hydrophobicity by microbial adhesion to solvents, antagonism against pathogenic bacteria (Staphylococcus aureus, Enterococcus faecalis, Bacillus cereus, Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica serovar Typhimurium and Listeria monocytogenes), production of hydrogen peroxide, and antibiotic susceptibility. Thirty four strains were highly resistant to acidic conditions with slight (18 strains) to moderate (16 strains) growth inhibition by bile salts. Seven isolates had highly hydrophobic cellular surfaces and 28 strains exhibited strong antagonism against the bacterial pathogens tested, although 8 isolates tested against Leptospira interrogans had no effect on pathogen growth. All isolates produced low rates of hydrogen peroxide. Based on these results, two Lactobacillus strains showed promising probiotic-related features and merit investigation as probiotics for dogs.

Colonization of the Mouse Upper Gastrointestinal Tract by Lactobacillus murinus: A Histological, Immunocytochemical, and Ultrastructural Study

Lactobacillus is normally present in animals and humans colonizing several epithelia, mainly those belonging to the upper gastrointestinal tract. Most of the information about the distribution of Lactobacillus in mice has been obtained by bacterial culture and characterization, and only few reports have described the direct presence of these bacteria in tissues, especially in the gastric mucosa. In this study, we have characterized and evaluated the location and detailed relationship between Lactobacillus and epithelia using a combination of histological, molecular, immunocytochemical and ultrastructural methods. Normal Balb/c mice were sacrificed to study esophagus and stomach. Partial 16S rRNA gene sequencing, Gram, and P.A. Schiff staining allowed us to demonstrate that Lactobacillus murinus isolated from each animal colonize not only the epithelium of the forestomach but also that belonging to the distal esophagus. The pattern of colonization was linear over the keratinized epithelium, and also in a vertical way of focal bacterial aggregates. This was confirmed by transmission electron microscopy, and the nature of bacteria was further assessed by immunocytochemistry. Our results indicate that L. murinus can colonize the stomach and the esophagus epithelia in a biofilm-like manner, possibly acting as a defense barrier against colonization by other bacteria.

Differential colonization with segmented filamentous bacteria and Lactobacillus murinus do not drive divergent development of diet-induced obesity in C57BL/6 mice

Alterations in the gut microbiota have been proposed to modify the development and maintenance of obesity and its sequelae. Definition of underlying mechanisms has lagged, although the ability of commensal gut microbes to drive pathways involved in inflammation and metabolism has generated compelling, testable hypotheses. We studied C57BL/6 mice from two vendors that differ in their obesogenic response and in their colonization by specific members of the gut microbiota having well-described roles in regulating gut immune responses. We confirmed the presence of robust differences in weight gain in mice from these different vendors during high fat diet stress. However, neither specific, highly divergent members of the gut microbiota (Lactobacillus murinus, segmented filamentous bacteria) nor the horizontally transmissible gut microbiota were found to be responsible. Constitutive differences in locomotor activity were observed, however. These data underscore the importance of selecting appropriate controls in this widely used model of human obesity.