Bactericidal effects of Cinnamon cassia oil against bovine mastitis bacterial pathogens

This study examined the antimicrobial activity of Cinnamon cassia oil against major pathogens causing bacterial bovine mastitis, its miscibility in milk and possible antimicrobial mechanisms. C. cassia oil had inhibitory activity against all tested pathogen isolates from bovine mastitis. We conducted disk diffusion assay and found that discs with 20 μL of 2% (v/v) C. cassia oil solution resulted in inhibition zones of 29.6, 19.1, 27.0, 33.3 and 30.7 mm for Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hyicus, Staphylococcus xylosus and Escherichia coli 29, respectively. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of C. cassia oil was 0.00625% and 0.025% (v/v) for S. hyicus, 0.025% and 0.10% (v/v) for E. coli 29, and 0.0125% and 0.05% for S. aureus, S. epidermidis and S. xylosus, respectively. We selected two common mastitis pathogens, a representative S. aureus isolate and E. coli 29 for further analyses. Based on time-kill assay in LB broth with 0.15% agar, 2MBC of C. cassia oil generated bactericidal effects on S. aureus and E. coli 29 within 30 min, and 4MBC caused 6 log reduction of S. aureus and E. coli 29 within 30 min. In milk, C. cassia oil at 4MBC reduced ∼6.0 Log10 CFU/ml of S. aureus and E. coli 29 to undetectable level within 8 h. Using propidium iodide staining, we observed membrane damage on both S. aureus and E. coli 29 cells during incubation with C. cassia oil. In ad...
Source: Food Control - Category: Food Science Source Type: research