Extracellular homopolysaccharides and oligosaccharides from intestinal lactobacilli

Aims: To characterize lactobacilli isolated from the intestines of ducks or pigs with respect to the production of extracellular homopolysaccharides (HoPS) and oligosaccharides. Methods and Results: 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. Conclusions: 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. Significance and Impact of the Study: 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.