Inhibition of Bacillus cereus in milk fermented with kefir grains.
The effects of kefir-fermented milk were tested against a toxigenic strain of Bacillus cereus. The incubation of milk with B. cereus spores plus 5% kefir grains prevented spore germination and growth of vegetative forms. In contrast, when 1% kefir grains was used, no effects were observed. The presence of metabolically active kefir grains diminished titers of nonhemolytic enterotoxin A, as assessed by enzyme-linked immunosorbent assay. During fermentation, kefir microorganisms produce extracellular metabolites such as organic acids, which could play a role in the inhibition of spore germination and growth of B. cereus, although the effect of other factors cannot be ruled out. Results of the present study show that kefir-fermented milk is able to antagonize key mechanisms involved in the growth of B. cereus as well as interfere with the biological activity of this microorganism.
Centro de Investigación y Desarrollo en Criotecnología de Alimentos (CIDCA), 47 y 116 (1900), Departamento de Ciencias Biológicas, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, La Plata, Argentina.
Emiliano J
EJ
Kakisu
Analía G
AG
Abraham
Pablo F
PF
Pérez
Graciela L
GL
De Antoni
D001409:Bacillus cereus / Q000254:growth & development*; D015169:Colony Count, Microbial; D043302:Cultured Milk Products / Q000382:microbiology*; D005285:Fermentation; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D013045:Species Specificity; D013171:Spores, Bacterial