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: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: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:Recent functional genomics and genome-scale modeling approaches indicated that B12 production in Lactobacillus reuteri could be improved by medium optimization. Here we show that a series of systematic single amino acid omissions could significantly modulate the production of B12 from nearly undetectable levels (by isoleucine omission) to 20-fold higher than previously reported through omission of cysteine. We analyzed by cDNA microarray experiments the transcriptional response of L. reuteri to the medium lacking cysteine. These results supported the observed high B12 production and provided new avenues for future improvement of production of vitamin B12. Keywords: cell type comparison
Project description:Analysis of gene expression in RAW264.7 cells stimulated for osteoclastogenesis and then treated with cell culture supernatant from Lactobacillus reuteri. Results will offer insight into targeted mechanisms suppressing osteoclastogenesis
Project description:Commensal (symbiont) bacteria form communities in various regions of the bodies of vertebrates. Phylogenetic analysis of gut communities is advanced, but the relationships, especially at the trophic level, between commensals that share gut habitats of monogastric animals have not been investigated to any extent. Lactobacillus reuteri strain 100-23 and Lactobacillus johnsonii strain 100-33 cohabit in the forestomach of mice. According to the niche exclusion principle, this should not be possible because both strains utilise the two main fermentable carbohydrates present in the stomach digesta: glucose and maltose. We show, based on gene transcription analysis, in vitro physiological assays, and in vivo experiments that the two strains can co-exist in the forestomach habitat because L. reuteri 100-23 transports maltose into its cells more efficiently than does L. johnsonii 100-33. Conversely, strain 100-33 transports glucose more efficiently than 100-23. As a result, 100-23 shows a preference for growth using maltose, whereas 100-33 prefers glucose. Mutation of the maltose phosphorylase gene (malA) of strain 100-23 prevented its growth on maltose-containing culture medium, and resulted in the numerical dominance of 100-33 in the forestomach. The fundamental niche of L. reuteri 100-23 in the mouse forestomach can be defined in terms of glucose and maltose fermentation. Its realised niche when L. johnsonii 100-33 is present is maltose fermentation. Hence nutritional adaptations provided niche differentiation that enabled cohabitation by the two strains through resource partitioning in the mouse forestomach. This real life, trophic phenomenon conforms to a mathematical model.