Antimicrobial effect of nisin extracted from Lactococcus lactis isolated from goat milk on some bacteria causing food spoilage

Nisin is a biological bacteriocin with many functions against food pathogenic bacteria. The disadvantages of chemical preservatives in foods have attracted attention to natural preservatives such as nisin. This study evaluated the antimicrobial properties of nisin extracted from Lactococcus lactis isolated from goat milk. Ten goat milk samples were collected from around Kerman city under sterile conditions, and Lactococcus lactis were isolated in the selected environment of Eliker-trimethoprim. Biochemical tests were used to Strain identification and nisin gene confirm by polymerase chain reaction with specific primers was used. HPLC method was used to confirm the presence of nisin using bacterially extracted proteins. The antibacterial properties of nisin were performed by disk diffusion agar method against Staphylococcus aureus, Bacillus cereus, Acinetobacter baumannii, and Pseudomonas aeruginosa. The minimum inhibitory concentration of bacteriocin was performed by Provide serial dilution in a microtiter plate. One of the four strains of Lactococcus lactis was identified and selected with the best growth conditions for further investigation. The presence of the nisin gene in Lactococcus lactis was confirmed by a specific primer and polymerase chain reaction method. The amount of nisin produced protein was 41.5 mg/kg. The diameter of inhibitory zone for Staphylococcus aureus, Bacillus cereus, Acinetobacter baumannii, and Pseudomonas aeruginosa were 13, 17, 14, and 0, respectively, and minimum inhibitory concentrations for extracted nisin were in dilutions of 10-5, 10-6, 10-5 and 10-1, respectively. Therefore, nisin extracted from Lactococcus lactis in goat milk can be a suitable substitute for chemical preservatives.