Analysis of the Genome Sequence ofLactobacillus gasseriATCC 33323 Reveals the Molecular Basis of an Autochthonous Intestinal Organism

Abstract

This study presents the complete genome sequence of Lactobacillus gasseri ATCC 33323, a neotype strain of human origin and a native species found commonly in the gastrointestinal tracts of neonates and adults. The plasmid-free genome was 1,894,360 bp in size and predicted to encode 1,810 genes. The GC content was 35.3%, similar to the GC content of its closest relatives, L. johnsonii NCC 533 (34%) and L. acidophilus NCFM (34%). Two identical copies of the prophage LgaI (40,086 bp), of the Sfi11-like Siphoviridae phage family, were integrated tandomly in the chromosome. A number of unique features were identified in the genome of L. gasseri that were likely acquired by horizontal gene transfer and may contribute to the survival of this bacterium in its ecological niche. L. gasseri encodes two restriction and modification systems, which may limit bacteriophage infection. L. gasseri also encodes an operon for production of heteropolysaccharides of high complexity. A unique alternative sigma factor was present similar to that of B. caccae ATCC 43185, a bacterial species isolated from human feces. In addition, L. gasseri encoded the highest number of putative mucusbinding proteins (14) among lactobacilli sequenced to date. Selected phenotypic characteristics that were compared between ATCC 33323 and other human L. gasseri strains included carbohydrate fermentation patterns, growth and survival in bile, oxalate degradation, and adhesion to intestinal epithelial cells, in vitro. The results from this study indicated high intraspecies variability from a genome encoding traits important for survival and retention in the gastrointestinal tract.

Inulin and levan synthesis by probiotic Lactobacillus gasseri strains: characterization of three novel fructansucrase enzymes and their fructan products

“…Supplementary material related to the published genome sequence of DSM 20243 (Azcarate-Peril et al, 2008) indicated the presence of two gene loci, LGAS_1281 and LGAS_1282, with assigned functions in fructan synthesis. However, analysis of the genome sequence (GenBank accession no.…”

“…3b). In a recent report (Azcarate-Peril et al, 2008), none of the nine L. gasseri strains tested, including the type strain (DSM 20243), was found to ferment raffinose. We also could not detect any growth or product formation by the three L. gasseri strains used in our studies, not even after 5 days of incubation with 500 mM raffinose (Fig.…”

“…Lactobacillus gasseri, which is speculated to be an autochthonous human intestinal organism (Azcarate-Peril et al, 2008), constitutes a major part of the homofermentative Lactobacillus species occupying the human GI tract (Kullen et al, 2000). L. gasseri is associated with a variety of probiotic functions including reduction of activities of faecal mutagenic enzymes (Pedrosa et al, 1995), adherence to intestinal tissues (Conway et al, 1987;Kirjavainen et al, 1998), stimulation of macrophages (Kirjavainen et al, 1999;Tejada-Simon & Pestka, 1999) and production of bacteriocins (Itoh et al, 1995).…”

Functional Characterization of a Mucus-Specific LPXTG Surface Adhesin from Probiotic Lactobacillus rhamnosus GG

“…The adhesion of L. rhamnosus GG cells to intestinal mucus was inhibited by anti-MBF serum using the procedure described previously (21,41). Briefly, 3 H-labeled wild-type (WT) L. rhamnosus GG cells were first preincubated with anti-SpaC pilin serum (diluted 1:100) and then treated either with or without anti-MBF serum (diluted 1:100). Antibody-untreated WT L. rhamnosus GG served as a positive adhesion control.…”

“…Moreover, homology-driven genome mining in several Lactobacillus spp. (3,7,8,11,33) has identified the presence of various-sized putative mucus adhesins consisting of one or more copies of an approximately 100-to 200-amino-acid (aa) mucus-binding (MUB) domain repeat, which, given its prevalence in lactic acid bacteria (LAB), can be considered a unique functional feature for promoting host-microbe interplay in the GI tract (7).…”