title: Inside the adaptation process of Lactobacillus delbrueckii subsp. lactis to bile.
abstract: Progressive adaptation to bile might render some lactobacilli able to withstand physiological bile salt concentrations. In this work, the adaptation to bile was evaluated on previously isolated dairy strains of Lactobacillus delbrueckii subsp. lactis 200 and L. delbrueckii subsp. lactis 200+, a strain derived thereof with stable bile-resistant phenotype. The adaptation to bile was obtained by comparing cytosolic proteomes of both strains grown in the presence or absence of bile. Proteomics were complemented with physiological studies on both strains focusing on glycolytic end-products, the ability to adhere to the human intestinal epithelial cell line HT29-MTX and survival to simulated gastrointestinal conditions. Protein pattern comparison of strains grown with and without bile allowed us to identify 9 different proteins whose production was regulated by bile in both strains, and 17 proteins that showed differences in their levels between the parental and the bile-resistant derivative. These included general stress response chaperones, proteins involved in transcription and translation, in peptidoglycan/exopolysaccharide biosynthesis, in the lipid and nucleotide metabolism and several glycolytic and pyruvate catabolism enzymes. Differences in the level of metabolic end-products of the sugar catabolism were found between the strains 200 and 200+. A decrease in the adhesion of both strains to the intestinal cell line was detected in the presence of bile. In simulated gastric and intestinal juices, a protective effect was exerted by milk improving the survival of both microorganisms. These results indicate that bile tolerance in L. delbrueckii subsp. lactis involves several mechanisms responding to the deleterious impact of bile salts on bacterial physiology.
authors.affiliation: Instituto de Lactología Industrial (INLAIN, UNL-CONICET), Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santa Fe, Argentina.
authors.forename: Patricia
authors.initials: P
authors.lastname: Burns
authors.forename: Borja
authors.initials: B
authors.lastname: Sánchez
authors.forename: Gabriel
authors.initials: G
authors.lastname: Vinderola
authors.forename: Patricia
authors.initials: P
authors.lastname: Ruas-Madiedo
authors.forename: Lorena
authors.initials: L
authors.lastname: Ruiz
authors.forename: Abelardo
authors.initials: A
authors.lastname: Margolles
authors.forename: Jorge
authors.initials: J
authors.lastname: Reinheimer
authors.forename: Clara G
authors.initials: CG
authors.lastname: de los Reyes-Gavilán
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects; D001422:Bacterial Adhesion / Q000187:drug effects; D001647:Bile Acids and Salts / Q000494:pharmacology*; D019073:HT29 Cells; D006801:Humans; D007422:Intestines / Q000382:microbiology; D048668:Lactobacillus delbrueckii / Q000187:drug effects / Q000502:physiology*; D008954:Models, Biological
chemical_list: D001647:Bile Acids and Salts