Extracellular homopolysaccharides and oligosaccharides from intestinal lactobacilli

Abstract

To characterize lactobacilli isolated from the intestines of ducks or pigs with respect to the production of extracellular homopolysaccharides (HoPS) and oligosaccharides. Lactobacillus strains of duck or pig origin were screened for HoPS synthesis and >25% of the isolates produced fructans or glucans from sucrose. Glucan-forming strains were found within the species Lactobacillus reuteri and Lactobacillus animalis and fructan-forming strains were found within Lactobacillus mucosae, Lactobacillus crispatus and Lactobacillus acidophilus. The glucan-forming strains of L. reuteri but not L. animalis produced glucose-oligosaccharides in additon to the respective polymers, and two fructan-forming strains of L. acidophilus produced kestose. Genes coding for glycosyltransferases were detected by PCR and partially characterized by sequence analysis. A large proportion of lactobacilli from intestinal habitats produce HoPS from sucrose and polysaccharide formation is generally associated with the formation of glucose- and fructose oligosaccharides. The characterization of the metabolic potential of intestinal lactobacilli contributes to the understanding of the molecular basis of autochthony in intestinal habitats. Moreover, this is the first report of glucose-oligosaccharide production during growth of lactobacilli, and one novel fructosyltransferase and one novel glucansucrase were partially characterized on the genetic level.