title: Production of growth-inhibiting factors by Lactobacillus delbrueckii.
abstract: OBJECTIVE
  The detection of growth-inhibiting factors produced by Lactobacillus delbrueckii.
  
  
  RESULTS
  A bioscreen assay was developed to study the effect of Lact. delbrueckii culture supernatant fluids on the growth of phylogenically or functionally related bacteria in broth cultures. Several growth-inhibiting factors could be distinguished based on differential effects on different test strains, separation by ultrafiltration and sensitivity to heat, proteinase treatment or catalase addition.
  
  
  CONCLUSIONS
  Lactobacillus delbrueckii strain VI1007 was found to produce at least three growth-inhibiting factors, other than lactic acid, when grown under microaerobic conditions in MRS broth. These included H2O2 and a bacteriocin-like, heat- and proteinase-sensitive bactericidal molecule or complex with a molecular weight greater than 50 kDa. A third factor inhibited the growth of Streptococcus thermophilus.
  
  
  CONCLUSIONS
  The assay system used allows the detection of subtle interactions between strains, that are likely to be of ecological importance in mixed cultures but would go unnoticed in classical agar diffusion tests.
authors.affiliation: Laboratoire de Génétique Microbienne, Institut National de la Recherche Agronomique-CRJ, 78452 Jouy-en-Josas cedex, France. guchte@biotec.jouy.inra.fr
authors.forename: M
authors.initials: M
authors.lastname: van de Guchte
authors.forename: S D
authors.initials: SD
authors.lastname: Ehrlich
authors.forename: E
authors.initials: E
authors.lastname: Maguin
mesh_terms: D000900:Anti-Bacterial Agents / Q000378:metabolism* / Q000494:pharmacology; D000898:Antibiosis; D001426:Bacterial Proteins / Q000378:metabolism* / Q000494:pharmacology; D018929:Cell Culture Techniques; D006131:Growth Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007778:Lactobacillus / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D013291:Streptococcus / Q000187:drug effects; D013696:Temperature
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D006131:Growth Inhibitors; D006861:Hydrogen Peroxide