Project description:Lactobacillus salivarius, found in the intestinal microbiota of humans and animals, is studied as an example of sub-dominant intestinal commensals that may impart benefits upon their host. Strains typically harbor at least one megaplasmid which encodes functions contributing to contingency metabolism and environmental adaptation. RNA-seq transcriptomic analysis of L. salivarius strain UCC118 identified the presence of a novel long and unusually abundant non-coding RNA (lancRNA) encoded by the megaplasmid and which represented more than 75% of total RNA-seq reads after depletion of ribosomal RNA species. The expression level of this 550 nt lancRNA in L. salivarius UCC118 exceeded that of the 16S rRNA, it accumulated during growth, was very stable over time, and was also expressed during intestinal transit in a mouse. This lancRNA sequence is specific to the L. salivarius species, however among 45 L. salivarius genomes analyzed, not all (only 34) harbored the sequence for the lancRNA. This lancRNA was produced in 27 tested L. salivarius strains but at strain-specific expression levels. High-level lancRNA expression correlated with high megaplasmid copy number. Transcriptome analysis of a deletion mutant lacking this lancRNA identified altered expression levels of genes in a number of pathways but a definitive function of this new long non-coding RNA was not identified. This lancRNA presents distinctive and unique properties, and suggests potential basic and applied scientific developments of this phenomenon.
Project description:Purpose: To understand the metabolic mechanism of Lactobacillus salivarius Ren in raffinose Methods: Samples of Lactobacillus salivarius Ren grown in glucose and raffinose were sequenced on the Illumina Hiseq platform. Three independent biological replicates were generated, including a total of six samples. Results: Raw data were firstly processed through in-house perl scripts to generate clean data, and then clean date were mapped to the reference genome, getting about 8-10 million total mapped reads per sample.
Project description:M cells are the main site of bacterial translocation in the intestine. We used the in vitro M cell model to study the effect of the commensal bacteria; Lactobacillus salivarius, Eschericha coli and Bacteroides fragilis, on M cell gene expression. Bacterial translocation across the gut mucosa has traditionally been based on the detection of commensals in the mesenteric lymph node. Differential rates of commensal translocation have been reported in vivo, however fewer studies have examined translocation of commensals at the level of the gut epithelial M cell. In this study we employed an in vitro M cell model to quantify translocation of various bacteria. C2BBe1 cells were differentiated into M cells and the gene expression profile and transport kinetics of different bacterial strains, namely Lactobacillus salivarius, Escherichia coli, and Bacteroides fragilis, was assessed. For comparison with M cell uptake, the THP-1 monocytic cell line was used to analyze bacterial internalization and resulting cytokine production. The commensal bacterial strains were translocated across M cells with different efficiencies; E. coli and B. fragilis translocated with equal efficiency while L. salivarius translocated with less efficiency. In contrast, L. salivarius was internalized by THP-1 cells to a higher degree than B. fragilis or E. coli and was associated with a different cytokine profile. Microarray analysis showed both common and differential gene expression amongst the bacteria and control polystyrene beads. In the presence of bacteria, but not beads, upregulated genes were mainly involved in transcription regulation and dephosphorylation, e.g. EGR1, JUN; whereas proinflammatory and stress response genes were primarily upregulated by E. coli and B. fragilis, but not L. salivarius nor beads, e.g. IL8, TNFAIP3. These results demonstrate that M cells have the ability to discriminate between different commensal bacteria and modify subsequent immune responses. C2bbe1 cells were converted to M cells (C2M) following 21 days of culture on Transwells in the presence of Raji B cells. C2M cells were co-cultured alone, Lactobacillus salivarius, Eschericha coli, Bacteroides fragilis and control beads. Total RNA was extracted and processed for Affymetrix array hybridisation
Project description:The genus Lactobacillus contains over 100 different species that were traditionally considered to be uniformly non-motile. However, at least twelve motile species are known to exist in the L. salivarius clade of this genus. Of these, Lactobacillus rumnis is the only motile species that is also autochthonous to the mammalian gastrointestinal tract. The genomes of two L. ruminis strains, ATCC25644 (human isolate, non-motile) and ATCC27782 (bovine isolate, motile) were sequenced and annotated to identify the genes responsible for flagellum biogenesis and chemotaxis in this species. Transcriptome analysis revealed that motility genes were transcribed at a significantly higher level in motile L. ruminis ATCC27782 than in non-motile ATCC25644 during the motile growth phase.