Evaluation of Antibacterial and Antibiofilm Activity of Essential Oils Against Isolated Bacteria from Milk Samples

Abstract

The consumption of food contaminated with bacteria or their toxins can result in foodborne infections or illnesses. This study investigated the antibacterial and antibiofilm activity of essential oils against bacteria isolated from milk samples collected in Pune, Maharashtra, India. Twenty-five raw milk samples were collected from local vendors and examined for the presence of biofilm-forming microorganisms. The isolated bacteria were identified and characterized using morphological and biochemical tests, revealing that 20% of the samples were contaminated with Acinetobacter spp. and 28% with E. coli. The antibacterial activity of the essential oils was evaluated using the disc diffusion method, and the minimum inhibitory concentration (MIC) was determined using 96-well plates. The minimum bactericidal concentration (MBC) was also assessed by inoculating assay mixtures from wells exhibiting no microbial growth onto sterile nutrient agar medium. Biofilm formation and disruption were evaluated using crystal violet assay and biofilm disruption assay, respectively. The results demonstrated that the Cinnamon Bark and Oregano essential oils exhibited significant antibacterial and antibiofilm activity at the lowest MIC value of 0.02-0.04 μg/ml against the isolated bacteria. The findings suggest that essential oils could be potential natural alternatives to conventional antibiotics for controlling bacterial contamination and biofilm formation in milk and dairy products. Further research is needed to explore the practical applications of essential oils in the dairy industry and to ensure their safety and efficacy as natural antimicrobial agents.