Dataset Information

Identification of a Gene Cluster for the Biosynthesis of a Long, Galactose-Rich Exopolysaccharide in Lactobacillus rhamnosus GG and Functional Analysis of the Priming Glycosyltransferase.

ABSTRACT: Cell surface polysaccharides have an established role as virulence factors in human bacterial pathogens. Less documented are the biosynthesis and biological functions of surface polysaccharides in beneficial bacteria. We identified a gene cluster that encodes the enzymes and regulatory and transporter proteins for the different steps in the biosynthesis of extracellular polysaccharides (EPS) of the well-documented probiotic strain Lactobacillus rhamnosus GG. Subsequent mutation of the welE gene, encoding the priming glycosyltransferase within this cluster, and comparative phenotypic analyses of wild-type versus mutant strains confirmed the specific function of this gene cluster in the biosynthesis of high-molecular-weight, galactose-rich heteropolymeric EPS molecules. The phenotypic analyses included monomer composition determination, estimation of the polymer length of the isolated EPS molecules, and single-molecule force spectroscopy of the surface polysaccharides. Further characterization of the welE mutant also showed that deprivation of these long, galactose-rich EPS molecules results in an increased adherence and biofilm formation capacity of L. rhamnosus GG, possibly because of less shielding of adhesins such as fimbria-like structures.

SUBMITTER: Lebeer S

PROVIDER: S-EPMC2687306 | biostudies-literature | 2009 Jun

REPOSITORIES: biostudies-literature

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Identification of a Gene Cluster for the Biosynthesis of a Long, Galactose-Rich Exopolysaccharide in Lactobacillus rhamnosus GG and Functional Analysis of the Priming Glycosyltransferase.

Lebeer Sarah S Verhoeven Tine L A TL Francius Grégory G Schoofs Geert G Lambrichts Ivo I Dufrêne Yves Y Vanderleyden Jos J De Keersmaecker Sigrid C J SC

Applied and environmental microbiology 20090403 11

Cell surface polysaccharides have an established role as virulence factors in human bacterial pathogens. Less documented are the biosynthesis and biological functions of surface polysaccharides in beneficial bacteria. We identified a gene cluster that encodes the enzymes and regulatory and transporter proteins for the different steps in the biosynthesis of extracellular polysaccharides (EPS) of the well-documented probiotic strain Lactobacillus rhamnosus GG. Subsequent mutation of the welE gene, ...[more]

PMID: 19346339

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Project description:BACKGROUND:Acute gastroenteritis develops in millions of children in the United States every year, and treatment with probiotics is common. However, data to support the use of probiotics in this population are limited. METHODS:We conducted a prospective, randomized, double-blind trial involving children 3 months to 4 years of age with acute gastroenteritis who presented to one of 10 U.S. pediatric emergency departments. Participants received a 5-day course of Lactobacillus rhamnosus GG at a dose of 1×1010 colony-forming units twice daily or matching placebo. Follow-up surveys were conducted daily for 5 days and again 14 days after enrollment and 1 month after enrollment. The primary outcome was moderate-to-severe gastroenteritis, which was defined as an illness episode with a total score on the modified Vesikari scale of 9 or higher (scores range from 0 to 20, with higher scores indicating more severe disease), within 14 days after enrollment. Secondary outcomes included the duration and frequency of diarrhea and vomiting, the duration of day-care absenteeism, and the rate of household transmission (defined as the development of symptoms of gastroenteritis in previously asymptomatic household contacts). RESULTS:Among the 971 participants, 943 (97.1%) completed the trial. The median age was 1.4 years (interquartile range, 0.9 to 2.3), and 513 participants (52.9%) were male. The modified Vesikari scale score for the 14-day period after enrollment was 9 or higher in 55 of 468 participants (11.8%) in the L. rhamnosus GG group and in 60 of 475 participants (12.6%) in the placebo group (relative risk, 0.96; 95% confidence interval, 0.68 to 1.35; P=0.83). There were no significant differences between the L. rhamnosus GG group and the placebo group in the duration of diarrhea (median, 49.7 hours in the L. rhamnosus GG group and 50.9 hours in the placebo group; P=0.26), duration of vomiting (median, 0 hours in both groups; P=0.17), or day-care absenteeism (median, 2 days in both groups; P=0.67) or in the rate of household transmission (10.6% and 14.1% in the two groups, respectively; P=0.16). CONCLUSIONS:Among preschool children with acute gastroenteritis, those who received a 5-day course of L. rhamnosus GG did not have better outcomes than those who received placebo. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development and others; ClinicalTrials.gov number, NCT01773967 .).

Dataset Information

Identification of a Gene Cluster for the Biosynthesis of a Long, Galactose-Rich Exopolysaccharide in Lactobacillus rhamnosus GG and Functional Analysis of the Priming Glycosyltransferase.

Publications

Identification of a Gene Cluster for the Biosynthesis of a Long, Galactose-Rich Exopolysaccharide in Lactobacillus rhamnosus GG and Functional Analysis of the Priming Glycosyltransferase.

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