title: Screening in a Lactobacillus delbrueckii subsp. bulgaricus collection to select a strain able to survive to the human intestinal tract.
abstract: OBJECTIVE
  Genetic diversity and resistance of Lactobacillus bulgaricus sbsp. delbrueckii collection with 100 isolates from different home-made yogurt in rural Bulgarian areas were determined.
  
  
  METHODS
  The strain K98 was the most resistant to bile salts and low pH. Survival and effects on short chain fatty acids production were tested in 20 healthy volunteers. High genetic diversity was observed in the L. bulgaricus collection by RAPD, whereas the ability of tolerate high deoxycholic acid concentrations, and different acid pHs was variable. The strain K98 was selected and used to prepare a homemade yogurt which was administered to 20 healthy volunteers (500 ml/day during 15d). A basal faecal sample and another after yogurt intake were recovered.
  
  
  RESULTS
  DGGE experiments, using both universal and Lactic Acid Bacteria (LAB) primers, demonstrated no significant changes in the qualitative composition of gut microbiota. A band corresponding to L. bulgaricus was observed in all 20 samples. Viable L. bulgaricus K98 strain was only recovered in one volunteer. After yogurt intake we found an increase of LAB and Clostridium perfringens, and a decrease of Bacteroides- Prevotella-Porphyromonas. In addition, increases of acetic, butyric and 2-hydroxy-butyric acids in faeces were detected.
  
  
  CONCLUSIONS
  Genetic diversity of L. delbrueckii subsp. bulgaricus especie is high We have isolated a probiotic resistant strain to bile and high acidity, L. delbrueckii subsp. bulgaricus-K98. Qualitative and quantitative changes in the intestinal microbiota are found after ingestion of a homemade yogurt containing this strain, with a concomitant increase in faecal SCFA. Our findings support the interest in developing further studies providing different amounts of L. delbrueckii subsp. bulgaricus-K98, and should evaluate its clinical effects in human disease.
authors.affiliation: Departamento de Nutrición y Obesidad, y CIBER de Fisiopatología de la Obesidad y Nutrición (CIBERobn), Hospital Universitario Ramón y Cajal y Instituto Ramón y Cajal de Investigación Sanitaria (IRYCIS), Madrid, Spain. cvazquez.hrc@salud.madrid.org
authors.forename: Clotilde
authors.initials: C
authors.lastname: Vázquez
authors.forename: José I
authors.initials: JI
authors.lastname: Botella-Carretero
authors.forename: Raimundo
authors.initials: R
authors.lastname: García-Albiach
authors.forename: María J
authors.initials: MJ
authors.lastname: Pozuelo
authors.forename: Mercedes
authors.initials: M
authors.lastname: Rodríguez-Baños
authors.forename: Fernando
authors.initials: F
authors.lastname: Baquero
authors.forename: María A
authors.initials: MA
authors.lastname: Baltadjieva
authors.forename: Rosa
authors.initials: R
authors.lastname: del Campo
mesh_terms: D000328:Adult; D001647:Bile Acids and Salts / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005243:Feces / Q000382:microbiology; D005260:Female; D014644:Genetic Variation; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007422:Intestines / Q000382:microbiology*; D048668:Lactobacillus delbrueckii / Q000235:genetics / Q000502:physiology*; D008297:Male; D008826:Microbial Sensitivity Tests; D019936:Probiotics; D060888:Real-Time Polymerase Chain Reaction; D013045:Species Specificity; D015014:Yogurt / Q000382:microbiology
chemical_list: D001647:Bile Acids and Salts