Bacillus megaterium isolates from honey: Cytotoxic effects on the human intestinal epithelial cell line Caco-2

LÓPEZ, A.C.; MINNAARD, J. PEREZ, P.F. & ALIPPI, A.M

Buenos Aires

Congreso; 42nd International Apicultural Congress; 2011

Apimondia

Honey quality is influenced by microorganisms, particularly yeasts and spore‐forming bacteria. As Bacillus megaterium is commonly found in Argentinian honeys, the aim of this study was to evaluate the interaction of B. megaterium with Caco‐2 cells monolayers. Epithelial cells were grown in DMEM plus 15 % fetal calf serum (37 °C, 15 days, 5 % CO2 ? 95 % air atmosphere). Bacterial strains were incubated in Luria Bertani (LB) broth (32°C for 3 h) under agitation. After centrifugation, pellets were suspended in DMEM plus 100 μg/ml cloramphenicol and cell density standardized. Infection assays were incubated for 2 h at 37 °C in a 5% CO2 ? 95 % air atmosphere. The invasion was assessed by the aminoglycosid protection assay. Quantitative association and invasion were evaluated by plate counting in nutritive agar. Results showed that 6 strains tested adhered to and invaded monolayers. Adhesion values were similar for all the strains but two strains showed the highest invasion values. Epithelial cells were detached after infection when no cloramphenicol was used, suggesting that protein synthesis is involved in biological activity. This is the first report on the direct interaction between B. megaterium and Caco‐2 cells.