Project description:Lactobacillus johnsonii NCC 533 is a member of the acidophilus group of intestinal lactobacilli that has been extensively studied for their "probiotic" activities that include, pathogen inhibition, epithelial cell attachment, and immunomodulation. To gain insight into its physiology and identify genes potentially involved in interactions with the host, we sequenced and analyzed the 1.99-Mb genome of L. johnsonii NCC 533. Strikingly, the organism completely lacked genes encoding biosynthetic pathways for amino acids, purine nucleotides, and most cofactors. In apparent compensation, a remarkable number of uncommon and often duplicated amino acid permeases, peptidases, and phosphotransferase-type transporters were discovered, suggesting a strong dependency of NCC 533 on the host or other intestinal microbes to provide simple monomeric nutrients. Genome analysis also predicted an abundance (>12) of large and unusual cell-surface proteins, including fimbrial subunits, which may be involved in adhesion to glycoproteins or other components of mucin, a characteristic expected to affect persistence in the gastrointestinal tract (GIT). Three bile salt hydrolases and two bile acid transporters, proteins apparently critical for GIT survival, were also detected. In silico genome comparisons with the >95% complete genome sequence of the closely related Lactobacillus gasseri revealed extensive synteny punctuated by clear-cut insertions or deletions of single genes or operons. Many of these regions of difference appear to encode metabolic or structural components that could affect the organisms competitiveness or interactions with the GIT ecosystem.
Project description:Oxygen relieves the CO2 and acetate dependency of Lactobacillus johnsonii NCC 533. The probiotic Lactobacillus johnsonii NCC 533 is relatively sensitive to oxidative stress; the presence of oxygen causes a lower biomass yield due to early growth stagnation. We show however that oxygen can also be beneficial to this organism as it relieves the requirement for acetate and CO2 during growth. Both on agar- and liquid-media, anaerobic growth of L. johnsonii NCC 533 requires CO2 supplementation of the gas phase. Switching off the CO2 supply induces growth arrest and cell death. The presence of molecular oxygen overcomes the CO2 dependency. Analogously, L. johnsonii NCC 533 strictly requires media with acetate to sustain anaerobic growth, although supplementation at a level that is 100-fold lower (120 microM) than the concentration in regular growth medium for lactobacilli already suffices for normal growth. Analogous to the CO2 requirement, oxygen supply relieves this acetate-dependency for growth. The L. johnsonii NCC 533 genome indicates that this organism lacks genes coding for pyruvate formate lyase (PFL) and pyruvate dehydrogenase (PDH), both CO2 and acetyl-CoA producing systems. Therefore, C1- and C2- compound production is predicted to largely depend on pyruvate oxidase activity (POX). This proposed role of POX in C2/C1-generation is corroborated by the observation that in a POX deficient mutant of L. johnsonii NCC 533, oxygen is not able to overcome acetate dependency nor does it relieve the CO2 dependency.
Project description:Fructansucrase enzymes polymerize the fructose moiety of sucrose into levan or inulin fructans, with beta(2-6) and beta(2-1) linkages, respectively. The probiotic bacterium Lactobacillus johnsonii strain NCC 533 possesses a single fructansucrase gene (open reading frame AAS08734) annotated as a putative levansucrase precursor. However, (13)C nuclear magnetic resonance (NMR) analysis of the fructan product synthesized in situ revealed that this is of the inulin type. The ftf gene of L. johnsonii was cloned and expressed to elucidate its exact identity. The purified L. johnsonii protein was characterized as an inulosucrase enzyme, producing inulin from sucrose, as identified by (13)C NMR analysis. Thin-layer chromatographic analysis of the reaction products showed that InuJ synthesized, besides the inulin polymer, a broad range of fructose oligosaccharides. Maximum InuJ enzyme activity was observed in a pH range of 4.5 to 7.0, decreasing sharply at pH 7.5. InuJ exhibited the highest enzyme activity at 55 degrees C, with a drastic decrease at 60 degrees C. Calcium ions were found to have an important effect on enzyme activity and stability. Kinetic analysis showed that the transfructosylation reaction of the InuJ enzyme does not obey Michaelis-Menten kinetics. The non-Michaelian behavior of InuJ may be attributed to the oligosaccharides that were initially formed in the reaction and which may act as better acceptors than the growing polymer chain. This is only the second example of the isolation and characterization of an inulosucrase enzyme and its inulin (oligosaccharide) product from a Lactobacillus strain. Furthermore, this is the first Lactobacillus strain shown to produce inulin polymer in situ.
Project description:Whole genome DNA microarray designed for the probiotic L. johnsonii strain NCC533 was used for comparative genomic hybridization (CGH) of L. johnsonii ATCC 33200T, L. johnsonii BL261, L. gasseri ATCC 33323T and L. iatae BL263 (CECT 7394T). In these experiments, the fluorescence ratio distributions obtained with L. iatae and L. gasseri showed characteristic inter-species profiles. The percentage of conserved L. johnsonii NCC533 genes was about 83% in the L. johnsonii strains comparisons and decreased to 51% and 47% for L. iatae and L. gasseri, respectively. These results confirmed the separate status of L. iatae from L. johnsonii at the level of species, and also that it is closer to L. johnsonii than L. gasseri.
Project description:Heat shock proteins of the GroEL or Hsp60 class are highly conserved proteins essential to all living organisms. Even though GroEL proteins are classically considered intracellular proteins, they have been found at the surface of several mucosal pathogens and have been implicated in cell attachment and immune modulation. The purpose of the present study was to investigate the GroEL protein of a gram-positive probiotic bacterium, Lactobacillus johnsonii La1 (NCC 533). Its presence at the bacterial surface was demonstrated using a whole-cell enzyme-linked immunosorbent assay and could be detected in bacterial spent culture medium by immunoblotting. To assess binding of La1 GroEL to mucins and intestinal epithelial cells, the La1 GroEL protein was expressed in Escherichia coli. We report here that La1 recombinant GroEL (rGroEL) binds to mucins and epithelial cells and that this binding is pH dependent. Immunomodulation studies showed that La1 rGroEL stimulates interleukin-8 secretion in macrophages and HT29 cells in a CD14-dependent mechanism. This property is common to rGroEL from other gram-positive bacteria but not to the rGroEL of the gastric pathogen Helicobacter pylori. In addition, La1 rGroEL mediates the aggregation of H. pylori but not that of other intestinal pathogens. Our in vitro results suggest that GroEL proteins from La1 and other lactic acid bacteria might play a role in gastrointestinal homeostasis due to their ability to bind to components of the gastrointestinal mucosa and to aggregate H. pylori.
Project description:Whole genome DNA microarray designed for the probiotic L. johnsonii strain NCC533 was used for comparative genomic hybridization (CGH) of L. johnsonii ATCC 33200T, L. johnsonii BL261, L. gasseri ATCC 33323T and L. iatae BL263 (CECT 7394T). In these experiments, the fluorescence ratio distributions obtained with L. iatae and L. gasseri showed characteristic inter-species profiles. The percentage of conserved L. johnsonii NCC533 genes was about 83% in the L. johnsonii strains comparisons and decreased to 51% and 47% for L. iatae and L. gasseri, respectively. These results confirmed the separate status of L. iatae from L. johnsonii at the level of species, and also that it is closer to L. johnsonii than L. gasseri. L. johnsonii, L. gasseri, and L. iatae strains were hybridized versus L. johnsonii NCC533, some with replicates
Project description:In Lactobacillus johnsonii strain NCC533, two prophages were integrated into tRNA genes and one was disrupted by integration. In a survey, the prophages were restricted to strains sharing an essentially identical restriction pattern. Microarray analysis showed that the prophage DNA represents about 50% of the NCC533 strain-specific DNA.
Project description:Work with pathogens like Vibrio cholerae has shown major differences between gene expression in bacteria grown in vitro and in vivo. To explore this subject for commensals, we investigated the transcription of the Lactobacillus johnsonii NCC533 genome during in vitro using the microarray technology. In broth growth, 537, 626 and 277 of the 1756 tested genes were expressed during exponential, “adaptation” (early stationary phase) and stationary phase, respectively. One hundred-one, 150 and 33 genes, respectively, were specifically transcribed in these three phases. Forty-four per cent of the NCC533 genome were not detectably transcribed under any of the investigated conditions. Non-transcribed genes were clustered on the genome and enriched in the variable genome part. For gene expression profiling experiments, cells were grown in a Sixfors fermentor system, composed of four individual 500 ml vessels (Infors, Bottmingen, Switzerland). Growth curves were performed at least in triplicate using the four separate fermentation vessels (fermentor 1 to 4), which were inoculated at 0.4% (v/v) with four individual overnight cultures in order to reach a starting optical density (OD600nm) of 0.05. Samples were taken at regular intervals from the four vessels to measure the OD600 nm and determine the CFU/ml until 36 h of fermentation. Aliquots of 15 ml (for early (T1-T2) and mid-exponential phases (T3-T4)) and 10 ml (for adaptation (T5), mid-stationary (T6) and late stationary phases (T7)) were centrifuged for 5 min at 10,000 x g at 4°C. Cell pellets were snap frozen in liquid nitrogen and stored at –80°C until further use.L. johnsonii NCC533 was grown in MRS broth supplemented with 2 % glucose as carbon source and 0.05% cysteine as redox buffer. For mRNA isolation L. johnsonii NCC533 cells were harvested from the broth culture several time points after inoculation (Fig. 1). In a total of 27 hybridization experiments. Genes were scored as expressed when their signal was detected in all hybridization experiments (with two technical replicates per slide) with mRNA preparations obtained from three independent growth experiments. Keywords: Growth phases of Lactobacillus johnsonii NCC533 in MRS