Evaluation of Efficiency and Extent of Inhibitory Characteristics of Lactobacillus spp. (Lactobacillus plantarum) against Selected Pathogenic Bacteria

Abstract

Background: Despite the improved modern technologies to inactivate pathogens, there has been a continuous surge of food-borne diseases involving many bacterial pathogens like Staphylococcus aureus, Escherichia coli, Bacillus cereus, Salmonella, Campylobacter, Listeria etc. Physical methods of reduction of microbial load in raw foods have been known to negatively impact the organoleptic properties of the products hence reducing their acceptability. Therefore, knowing that food may be laden with many pathogens, the biocontrol methods may be an effective alternative to chemical and physical methods of preservation for eliminating pathogens. Methods: The pathogens to be tested in the experiment were recovered from various food sources and clinical samples viz., milk, raw chicken and a faecal sample, chicken. For evaluation of inhibitory characteristics of Lactobacillus spp. (Lactobacillus plantarum) against selected pathogenic bacteria the grown culture of pathogens (S. aureus, E. coli, B. cereus) was added with Lactobacillus spp. at different concentrations and incubated at 24, 36 and 48 hrs and mean CFU units were evaluated. All of the treated groups were compared with the concurrent untreated groups of respective bacteria. Result: After 24 hrs of incubation at 37°C, the mean colony forming units (CFU/ml) of S. aureus, E. coli, B. cereus in the cultured groups treated with 108, 107, 106, 105 and 104/ml of L. plantarum were 2.56 x 108, 2.78 x 108, 2.90 x 108, 3.03 x 108 and 39.19 x 108; 0.81 x 108, 1.09 x 108, 1.36 x 108, 1.85 x 108 and 24.62 x 108; 0.31 x 108, 0.43 x 108, 0.60 x 108, 0.69 x 108 and 7.12 x 108, respectively. Henceforth, the mean colony forming counts of all the three pathogens increased when the concentration of L. plantarum decreased.