Project description:Stress survival tactics in bacteria utalize the up- and down-regulation of stress response genes. In bacterial that lack classical stress response genes for oxidative stress, other cellular systems can be used for cell survival. We used custom microarrays to study the regulation of genes in Bifidobacterium longum strains to oxidative stress to elucidate novel stress response mechanisms.
Project description:Transcriptional profiling of Bifidobacterium longum mutant versus wt strain in exponentional phase Keywords: Characterization of natural mutant
Project description:Transcriptional profiling of Bifidobacterium longum mutant versus wt strain in exponentional phase Keywords: Characterization of natural mutant One B. longum mutant (HPR2) was analysed versus the wt strain NCC2705 in: exponential phase 37°,pH 6.0, MRS, headspace flushing with CO2. Three biological replicates.
Project description:Bifidobacterium longum is one of the natural inhabitants in human gastrointestinal tract. In order to colonize and exert particular functions in the gut, it has to be tolerant to the physiological concentrations of bile salts. In this work, we used RNA-Seq transcriptomics based on the Next-Generation Sequencing to investigate the global response to bile in B. longum BBMN68, a potential probiotic strain isolated from a healthy centenarian. In the presence of 0.75 g liter-1 ox-bile, the transcription of 236 genes were regulated (M-bM-^IM-% 3-fold, p < 0.001). Function analysis and Gene Ontology suggested that the bile stress response of B. longum BBMN68 covers almost all biological processes, including bile stress resistance, general stress response, central metabolic process, transmembrane transport, gene expression, cell proliferation and interaction with the host. Remarkably, 3 two-component systems and 11 transcription factors were up- or down-regulated by bile, and target genes of the regulators were identified by bacterial one-hybrid system and bioinformatics methods, resulting in a putative regulatory network that controls bile stress response in B. longum for the first time. This study significantly develops our understanding on bile stress response and brings new insight to the regulatory mechanism in bifidobateria. Whole mRNA profiles of B. longum BBMN68 growing in the absence (CK) and presence (OG) of ox-bile were generated using AB SOLiD technology and differentially expressed genes were anylyzed.
Project description:Bifidobacterium longum is one of the natural inhabitants in human gastrointestinal tract. In order to colonize and exert particular functions in the gut, it has to be tolerant to the physiological concentrations of bile salts. In this work, we used RNA-Seq transcriptomics based on the Next-Generation Sequencing to investigate the global response to bile in B. longum BBMN68, a potential probiotic strain isolated from a healthy centenarian. In the presence of 0.75 g liter-1 ox-bile, the transcription of 236 genes were regulated (≥ 3-fold, p < 0.001). Function analysis and Gene Ontology suggested that the bile stress response of B. longum BBMN68 covers almost all biological processes, including bile stress resistance, general stress response, central metabolic process, transmembrane transport, gene expression, cell proliferation and interaction with the host. Remarkably, 3 two-component systems and 11 transcription factors were up- or down-regulated by bile, and target genes of the regulators were identified by bacterial one-hybrid system and bioinformatics methods, resulting in a putative regulatory network that controls bile stress response in B. longum for the first time. This study significantly develops our understanding on bile stress response and brings new insight to the regulatory mechanism in bifidobateria.
Project description:The purpose of this project was to determine the whole transcriptome response of Bifidobacterium longum subsp. longum SC596 to pooled and individual human milk oligosaccharides (HMO) relative to lactose
Project description:Bifidobacterium longum strain BBMN68 is resistant to low concentrations of oxygen. In this study, a transcriptomic study was performed to detail the cellular response of B. longum strain BBMN68 to oxidative stress. Oxygen and its intermediate metabolites, reactive oxygen species (ROS), induced abundant changes in gene expression at the mRNA level. Increased expression was found for genes involved in ROS detoxification and the redox homeostasis system, protein and DNA synthesis and repair, the FeâS cluster assembly system, and biosynthesis of branched-chain amino acids and tetrahydrofolate. Among them, two classes of ribonucleotide reductase (RNR), which are important for deoxyribonucleotide biosynthesis, were rapidly and persistently induced: first, the class Ib RNR NrdHIEF and then the class III RNR NrdDG. The increased resistance to oxygen and hydrogen peroxide conferred by NADH oxidase was confirmed by its heterogeneous overexpression in B. longum strain NCC2705. In addition, cell-membrane and cell-wall compositions were modified, probably by an increase in cyclopropane fatty acids and a decrease in polysaccharides, respectively, resulting in improved cell hydrophobicity and autoaggregation; this subsequently reduced the permeation of dissolved oxygen into the cell. Taken together, the proposed cell model of B. longum responses to oxygen stress suggests that this bacterium employs a complex molecular defense mechanism against oxygen-induced stresses. Whole mRNA profiles of B. longum BBMN68 grown in the absence or presence of 3% oxygen were generated using AB SOLiD technology and differentially expressed genes were analyzed.
Project description:Bifidobacterium longum subsp. infantis is a bacterial commensal that colonizes the breast-fed infant gut where it utilizes indigestible components delivered in human milk. Accordingly, human milk contains several non-protein nitrogenous molecules, including urea at high abundance. This project investigates the degree to which urea is utilized as a primary nitrogen source by Bifidobacterium longum subsp. infantis and incorporation of hydrolysis products into the expressed proteome.
Project description:Although oral administration of Bifidobacterium longum (B. longum) relieves irritable bowel syndrome (IBS) symptoms in a clinical setting, the underlying mechanisms remain undetermined. Herein, we confirmed that B. longum ameliorated defecation habits and alleviated visceral hypersensitivity in water avoidance stress (WAS) rats. Further analysis revealed that B. longum enhanced mucosal repair, promoted the production of lysozyme, and ameliorated microbiota dysbiosis in WAS rats. These activities are all closely correlated with Paneth cell function. In vitro, we incubated primary cultured enteroids with B. longum and found that this bacterium promoted the proliferation of these organoids, which may be attributed to the up-regulated expression of the stem niche factors WNT3A and TGF-β which are serected by the Paneth cells. On the basis of our findings, we propose that B. longum relieves IBS by restoring the antimicrobial activity and stem niche maintenance functions of Paneth cells.