KEFIRAN ANAGONIZES CYTOPATHIC EFFECTS OF Bacillus cereus EXTRACELLULAR FACTORS

MEDRANO, M., PÉREZ, P.F., ABRAHAM, A.G

INTERNATIONAL JOURNAL OF FOOD MICROBIOLOGY

Año: 2008 p. 1 - 7

0168-1605

ABSTRACT   Kefiran, the polysaccharide produced by microorganisms present in kefir grains, is a water-soluble branched glucogalactan containing equal amounts of D-glucose and D-galactose. In this study, the effect of kefiran on the biological activity of Bacillus cereus extracellular factors was assessed by using cultured human enterocytes (Caco-2 cells) and human erythrocytes. In the presence of kefiran concentrations ranging from 300 to 1000 mg/L, the ability of Bacillus cereus spent culture supernatants to detach and damage cultured human enterocytes was significantly abrogated. In addition, mitochondrial dehydrogenase activity was higher when kefiran was present during the cell toxicity assays. Protection was also demonstrated in hemolysis and apoptosis/necrosis assays. Scanning electron microscopy showed the protective effect of kefiran against structural cell damages produced by factors synthesized by Bacillus cereus. Our findings demonstrate the ability of kefiran to antagonize key events of Bacillus cereus virulence thus giving new perspectives for the role of bacterial exopolysaccharides in functional foods.   Key words Kefiran, bacterial exopolysaccharides, Bacillus cereus, Caco-2 cells, virulence, protein toxins