Project description:Inflammatory diseases of the gut are associated with increased intestinal oxygen concentrations and high levels of inflammatory oxidants, including hydrogen peroxide (H2O2) and hypochlorous acid (HOCl), which are antimicrobial compounds produced by the innate immune system. This contributes to dysbiotic changes in the gut microbiome, including increased populations of pro-inflammatory enterobacteria (Escherichia coli and related species) and decreased levels of health-associated anaerobic Firmicutes and Bacteroidetes. The pathways for H2O2 and HOCl resistance in E. coli have been well-studied, but little is known about how commensal and probiotic bacteria respond to inflammatory oxidants. In this work, we have characterized the transcriptomic response of the anti-inflammatory, gut colonizing Gram-positive probiotic Lactobacillus reuteri to both H2O2 and HOCl. L. reuteri mounts distinct responses to each of these stressors, and both gene expression and survival were strongly affected by the presence or absence of oxygen. Oxidative stress response in L. reuteri required several factors not found in enterobacteria, including the small heat shock protein Lo18, polyphosphate kinase 2, and RsiR, an L. reuteri-specific regulator of anti-inflammatory mechanisms. These results raise the intriguing possibility of developing treatments for inflammatory gut diseases that could sensitize pro-inflammatory enterobacteria to killing by the immune system while sparing anti-inflammatory, health-associated species.
Project description:This SuperSeries is composed of the following subset Series: GSE11860: The impact of glycerol on the metabolism of Lactobacillus reuteri - Exploratory experiment GSE11861: The impact of glycerol on the metabolism of Lactobacillus reuteri - Main experiment Refer to individual Series
Project description:Bacterial membrane vesicles have been implicated in a broad range of functions in microbial communities from pathogenesis to gene transfer. Though first thought to be a phenomenon associated with Gram-negative bacteria, vesicle production in Staphylococcus aureus, Lactobacillus plantarum, and other Gram-positives has recently been described. Here we characterize MVs from three different Lactobacillus species (L. acidophilus, L. casei, and L. reuteri), determining that the size and protein composition of Lactobacillus-derived MVs have both similarities and differences with those produced by Gram-negative bacteria. Using proteomics, we identified more than 80 protein components from Lactobacillus-derived MVs, including some that were enriched in the vesicles themselves. For each species, vesicular proteins were categorized based on biological pathway and examined for subcellular localization signals in an effort to identify possible sorting mechanisms for MV proteins. Additionally, differences between MVs of other Lactobacillus species and Gram positive bacteria were highlighted. Information in this study will assist in elucidation of the formation and functions of MVs, as well as the development of therapeutic tools for vaccines, diagnosis, and therapeutic delivery.
Project description:The present study reports comparative surfacomics (study of cell-surface exposed proteins) of the probiotic Lactobacillus rhamnosus strain GG and the dairy strain Lc705.
Project description:Lactobacillus reuteri 100-23 is an autochthonous inhabitant of the rodent gastrointestinal system that adheres to the non-secretory epithelium of the forestomach and forms biofilms. Microarray analysis of the expression profile of L. reuteri 100-23 cells harvested from the stomach of ex-Lactobacillus-free mice, compared to those of L. reuteri 100-23 in laboratory culture, revealed an in vivo upregulation of a urease gene cluster by greater than 50-fold. Genes for urease production were absent in all publically available Lactobacillus genome sequences except L. reuteri 100-23 and have recently been identified as specific to rodent strains of L. reuteri (Frese et al. 2011). In the current study, the urease enzyme was shown to be functional. Supplementation with 2% urea allowed L. reuteri 100-23 to increase the pH of the culture medium. A mutant strain of L. reuteri 100-23 was developed by insertional inactivation of the ureC gene, which encodes the largest subunit of the urease enzyme. The mutant strain was unable to hydrolyze urea to increase the pH of culture medium, and did not survive acid stress at pH 2.5 for 6 h, even in the presence of urea. In contrast, the wild type strain was still viable after 6 h when 2% urea supplementation was included. When mice free of lactobacilli were inoculated with a mixture of equal numbers of wild type L. reuteri 100-23 and ureC mutant cells, the wild type constituted 99% of the resulting Lactobacillus population in the stomach, caecum and jejunum after one week (108 cells/gram of sample). This study has therefore shown the importance of a functional urease enzyme in the ecological fitness of L. reuteri 100-23.
Project description:Transcriptional profiling of Lactobacillus reuteri ATCC 55730 mid-log cultures before vs after exposure to 0.5% bovine bile (oxgall). Two sets of array experiments were performed. One set compared the expression profiles of L. reuteri ATCC 55730 cells before bile exposure vs cells that had been exposed to 0.5% bile for 15 minutes (bile shock). The other set compared the expression profiles of L. reuteri ATCC 55730 cells before bile exposure vs cells that had begun growing again in the presence of 0.5% bile (bile adaptation). Keywords: Stress response
Project description:Probiotic bacteria, specific representatives of bacterial species that are a common part of the human microbiota, are proposed to deliver health benefits to the consumer by modulation of intestinal function via largely unknown molecular mechanisms. To explore in vivo mucosal responses of healthy adults to probiotics, we obtained transcriptomes in an intervention study following a double-blind placebo-controlled cross-over design. In the mucosa of the proximal small intestine of healthy volunteers, probiotic strains from the species Lactobacillus acidophilus, L. casei and L. rhamnosus each induced differential gene regulatory networks and pathways in the human mucosa. Comprehensive analyses revealed that these transcriptional networks regulate major basal mucosal processes, and uncovered remarkable similarity to response profiles obtained for specific bioactive molecules and drugs. This study elucidates how intestinal mucosa of healthy humans perceive different probiotics and provides avenues for rationally designed tests of clinical applications. Keywords: mucosal response of healthy adult humans to lactic acid bacteria This study was set up according to a randomised double-blind cross-over placebo-controlled design. It contains transcriptional profiles from biopsies from 7 healthy individuals after oral intake of three different Lactobacillus species or placebo control. In total, this study includes data from 7 individuals x 4 treatments=28 arrays.