title: Microbiological characteristics of the probiotic strains B. longum BB536 and L. rhamnosus HN001 used in combination.
abstract: OBJECTIVE
  The aim of this study was to investigate the antagonistic activity between the probiotic strains Bifidobacterium longum (B. longum) BB536 and Lactobacillus rhamnosus (L. rhamnosus) HN001 (ZirCombi, Alfa Wassermann S.p.A., Italy) and to evaluate for the strains tested alone and in combination the resistance in simulated gastrointestinal conditions, the ability to adhere to epithelial intestinal cells and their competition for adhesion.
  
  
  METHODS
  The antagonism between B. longum BB536 and L. rhamnosus HN001 was tested modifying the agar diffusion method. The in vitro resistance to gastrointestinal condition of the two strains used alone or in combination was tested using low pH (3.0, 2.5 and 2.0) and different concentrations of bile salts (0.3%, 0.5% and 0.7%). The adhesion ability and the competition for adhesivity on human colon cancer HT-29 cells were tested modifying quantitative methods described in literature.
  
  
  RESULTS
  The results demonstrated that B. longum BB536 and L. rhamnosus HN001 showed no in vitro inhibition effect each other and a good resistance to low pH and to different concentrations of bile salts, that was enhanced when they were tested in combination. Moreover, the two strains tested alone and in combination showed a good adhesion on HT-29 cells and no mechanism of competition.
  
  
  CONCLUSIONS
  The study suggests that B. longum BB536 and L. rhamnosus HN001 used in combination show no antagonism and could have functional endosymbiotic effects on intestinal host-microbiota.
authors.affiliation: Department of Biomedical Sciences and Biotechnology, Section of Microbiology, University of Catania, Catania, Italy - blandino@unict.it.
authors.forename: R
authors.initials: R
authors.lastname: Inturri
authors.forename: A
authors.initials: A
authors.lastname: Stivala
authors.forename: G
authors.initials: G
authors.lastname: Blandino
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology*; D000069978:Bifidobacterium longum / Q000502:physiology*; D001647:Bile Acids and Salts / Q000737:chemistry; D002460:Cell Line; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007413:Intestinal Mucosa / Q000382:microbiology*; D007422:Intestines / Q000382:microbiology*; D052201:Lacticaseibacillus rhamnosus / Q000502:physiology*; D019936:Probiotics / Q000737:chemistry*
chemical_list: D001647:Bile Acids and Salts