The Combined effect of Rosmarinus officinalis L essential oil and Bacteriocin BacLP01 from Lactobacillus plantarum against Bacillus subtilis ATCC11778

Abstract

Combining bacterial metabolites and natural products of plants is one proposed alternative to antibiotic usage. Reports on such combinations are starting to emerge. This study aimed to determine the antibacterial potential of bacteriocin (BacLP01) produced by Lactobacillus plantarum and the essential oil of Rosmarinus officinalis L (ROEO) alone and their combination. Each antibacterial agent was tested against food-borne pathogens: Bacillus subtilis, Bacillus cereus, Escherichia coli, and Staphylococcus aureus using the agar well diffusion method. The antibacterial agents were evaluated from their minimum inhibitory concentration (MIC) against the test organisms. The checkerboard technique was performed to assess the resulting combination to determine the nature of the sum effects between antibacterial agents against B. subtilis ATCC11778. BacLP01 achieved the highest activity against B. subtilis, equivalent to 6400 AU/mL. ROEO showed an inhibition zone ranging from 10.23 ± 1.92 to 14.52 ± 0.83mm. S. aureus expressed the highest sensitivity to ROEO (14.52 ± 0.83 mm), and B. subilis presented low susceptibility with a 10.23± 1.92 mm diameter inhibition zone. Likewise, the synergistic effect of their combination on B. subilis ATCC11778 follows the same trend. The MICs for bacteriocin (BacLP01) and ROEO were 5 and 6.25 μL/mL, respectively. The result from FICI for the combination of BacLP01 and ROEO was 0.49, suggesting a synergistic interaction effect against B. subtilis. The study concluded that a combination of BacLP01 and ROEO could be an efficient means to control the presence of pathogenic bacteria in food.