Bacillus clausii Probiotic Strains Antimicrobial and Immunomodulatory ActivitiesUrdaci, Maria C, PHD; Bressollier, Philippe, PHD; Pinchuk, Irina, PHDJournal of Clinical Gastroenterology: July 2004 - Volume 38 - Issue - p S86-S90 doi: 10.1097/01.mcg.0000128925.06662.69 Probiotics, Prebiotics, and New Foods Buy Abstract Author InformationAuthors Article MetricsMetrics The clinical benefits observed with probiotic use are mainly attributed to the antimicrobial substances produced by probiotic strains and to their immunomodulatory effects. Currently, the best-documented probiotic bacteria used in human therapy are lactic acid bacteria. In contrast, studies aiming to characterize the mechanisms responsible for the probiotic beneficial effects of Bacillus are rare. The current work seeks to contribute to such characterization by evaluating the antimicrobial and immunomodulatory activities of probiotic B. clausii strains. B. clausii strains release antimicrobial substances in the medium. Moreover, the release of these antimicrobial substances was observed during stationary growth phase and coincided with sporulation. These substances were active against Gram-positive bacteria, in particular against Staphylococcus aureus, Enterococcus faecium, and Clostridium difficile. The antimicrobial activity was resistant to subtilisin, proteinase K, and chymotrypsin treatment, whereas it was sensitive to pronase treatment. The evaluation of the immunomodulatory properties of probiotic B. clausii strains was performed in vitro on Swiss and C57 Bl/6j murine cells. The authors demonstrate that these strains, in their vegetative forms, are able to induce NOS II synthetase activity, IFN-γ production, and CD4+ T-cell proliferation. From Laboratoire de Microbiologie, ENITA-University of Bordeaux, Gradignan, France. Received for publication January 13, 2004; accepted February 12, 2004. Reprints: Maria C. Urdaci, PhD, Laboratoire de Microbiologie, ENITA-University of Bordeaux, 1, Cours du Général de Gaulle, 33175 Gradignan, France (e-mail: email@example.com). © 2004 Lippincott Williams & Wilkins, Inc.