Extraction of a novel bacteriocin from Lacticaseibacillus casei VITCM05 and its antibacterial activity against major food-borne pathogens

Abstract

Bacteriocin acts as an antibacterial, food preservative, and anti-cancerous agent. Due to its multi-role in the recent field of food and health department, we aimed to isolate a novel peptide that could act both as an antibacterial and anti-cancer agent from low-cost food materials. The present research aims to extract and characterize the bacteriocin from the lactic acid bacteria isolated from different food samples. Based on phenotypical, biochemical, and 16sr RNA molecular sequencing, the isolate VITCM05 from fermented Cuminum cyminum was identified as Lacticaseibacillus casei. The extracted bacteriocin showed a broad-spectrum antibacterial activity against both Gram-positive bacteria such as Listeria monocytogenes, Staphylococcus aureus, and Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, and Salmonella typhi, using agar well diffusion assay (AWDA). The protein content was estimated to be 3.4 mg/mL using Lowry’s method and bacteriocin activity was found to be 800 arbitrary unit/mL, expressed as 2000 IU/mL checked against L. monocytogenes using AWDA. On treatment with trypsin, the bacteriocin completely lost its activity. Based on the outcome, it can be stated that the extracted bacteriocin was proteinaceous. The bacteriocin retained its activity at a low pH, while its effectiveness and stability could be seen in a range of pH 3–5, at 37°C for 24 h. Moreover, the crude bacteriocin showed its cold-resistant ability, by being stable at 4°C for 60 days.