International Journal of Medical Science and Pharmaceutical Research

Escherichia coli O157:H7 is an important foodborne pathogen that can cause serious gastrointestinal illness, and represents a significant public health threat because it has the potential to contaminate many different foods. There is rising interest in the use of bacteriocins produced by lactic acid bacteria as natural bio-preservatives for food, due to a growing demand for safe and natural food preservation methods. The present study was designed to assess and characterize the antimicrobial activity of bacteriocins originating from Lactobacillus acidophilus towards E. coli O157:H7 in different food systems. A controlled, randomized design laboratory-based experimental study was performed between winter 2024 and the beginning of summer 2025. Food matrices included meat (minced beef) and dairy products (pasteurized milk). Samples were inoculated with E. coli O157:H7, which were divided into four groups: negative control; positive control; treatment with crude bacteriocin and treatment with partially purified bacteriocin. The antimicrobial efficacy was determined by quantifying the count of bacteria (log CFU/g or mL) at various time intervals. Bacteriocin treatment resulted in a statistically significant reduction of E. coli O157:H7 counts in both food matrices (p < 0.001). In minced meat, the bacterial count decreased from 6.25 log CFU/g in the positive control group to 3.42 log CFU/g following treatment with crude bacteriocin, and further to 2.15 log CFU/g with purified bacteriocin treatment. Dairy products showed a more pronounced reduction, reaching counts of 5.80 log CFU/mL to 2.95 and 1.72 log CFU/mL, respectively. In both food systems, the partially purified form of bacteriocin was more antimicrobial than its crude counterpart. Finally, Lactobacillus acidophilus bacteriocins showed strong inhibition against E. coli O157:H7 in meat and dairy products and purification increased its effect. This discovery emphasizes the potential of bacteriocins as a natural and efficient bio-preservative in food systems which could support better food quality and safety.

E. coli O157:H7, Lactobacillus acidophilus, Bacteriocins, Food Safety

1. Baillo, A. A., Cisneros, L., Villena, J., Vignolo, G., & Fadda, S. (2023). Bioprotective lactic acid bacteria and lactic acid as a sustainable strategy to combat Escherichia coli O157:H7 in meat. Foods, 12(2), 231. https://doi.org/10.3390/foods12020231 
2. Breijyeh, Z., Jubeh, B., & Karaman, R. (2020). Resistance of Gram-Negative Bacteria to Current Antibacterial Agents and Approaches to Resolve It. Molecules (Basel, Switzerland), 25(6), 1340. https://doi.org/10.3390/molecules25061340
3. Darbandi, A., Asadi, A., Mahdizade Ari, M., Ohadi, E., Talebi, M., Halaj Zadeh, M., Darb Emamie, A., Ghanavati, R., & Kakanj, M. (2022). Bacteriocins: Properties and potential use as antimicrobials. Journal of clinical laboratory analysis, 36(1), e24093. https://doi.org/10.1002/jcla.24093
4. Elsherif, W. M., Hassanien, A. A., Zayed, G. M., et al. (2024). Natural approach of using nisin and its nanoform as food bio-preservatives against methicillin-resistant Staphylococcus aureus and E. coli O157:H7 in yoghurt. BMC Veterinary Research, 20, 192. https://doi.org/10.1186/s12917-024-03985-1 
5. Elsherif, W. M., Hassanien, A. A., Zayed, G. M., et al. (2024). Natural approach of using nisin and its nanoform as food bio-preservatives against methicillin-resistant Staphylococcus aureus and E. coli O157:H7 in yoghurt. BMC Veterinary Research, 20, 192. https://doi.org/10.1186/s12917-024-03985-1
6. Gaur, A., Singhal, N., Vardhan, H., Jain, R., Bist, Y., & Wagri, N. K. (2025). Cultivation to consumption: strengthening bacterial safety in plant-based nutraceuticals. Frontiers in microbiology, 16, 1698580. https://doi.org/10.3389/fmicb.2025.1698580
7. Lahiri, D., Nag, M., Dutta, B., Sarkar, T., Pati, S., Basu, D., Abdul Kari, Z., Wei, L. S., Smaoui, S., Wen Goh, K., & Ray, R. R. (2022). Bacteriocin: A natural approach for food safety and food security. Frontiers in bioengineering and biotechnology, 10, 1005918. https://doi.org/10.3389/fbioe.2022.1005918
8. Mills, S., Ross, R. P., & Hill, C. (2017). Bacteriocins and bacteriophage: A narrow-minded approach to food and gut microbiology. FEMS Microbiology Reviews, 41(Suppl_1), S129–S153. https://doi.org/10.1093/femsre/fux022
9. Muthuvelu, K. S., Ethiraj, B., Pramnik, S., Raj, N. K., Venkataraman, S., Rajendran, D. S., Bharathi, P., Palanisamy, E., Narayanan, A. S., Vaidyanathan, V. K., & Muthusamy, S. (2023). Biopreservative technologies of food: an alternative to chemical preservation and recent developments. Food science and biotechnology, 32(10), 1337–1350. https://doi.org/10.1007/s10068-023-01336-8
10. Öncül, N., & Yıldırım, Z. (2019). Inhibitory effect of bacteriocins against Escherichia coli O157:H7. Food Science and Technology International, 25(6), 504–514. https://doi.org/10.1177/1082013219840462 
11. Puligundla, P., & Lim, S. (2022). Biocontrol approaches against Escherichia coli O157:H7 in foods. Foods, 11(5), 756. https://doi.org/10.3390/foods11050756 
12. Singha, S., Thomas, R., Viswakarma, J. N., & Gupta, V. K. (2023). Foodborne illnesses of Escherichia coli O157origin and its control measures. Journal of food science and technology, 60(4), 1274–1283. https://doi.org/10.1007/s13197-022-05381-9
13. Xu, C., Xin, Z., Yu, R., Li, J., Dan, W., & Dai, J. (2025). The control strategies for E. coli O157:H7 in food processing at the physical, chemical and biological levels. Frontiers in Microbiology, 16, 1598090. https://doi.org/10.3389/fmicb.2025.1598090 
14. Xu, C., Xin, Z., Yu, R., Li, J., Dan, W., & Dai, J. (2025). The control strategies for E. coli O157:H7 in food processing at the physical, chemical and biological levels. Frontiers in Microbiology, 16, 1598090. https://doi.org/10.3389/fmicb.2025.1598090
15. Yu, W., Guo, J., Liu, Y., Xue, X., Wang, X., Wei, L., & Ma, J. (2023). Potential impact of combined inhibition by bacteriocins and chemical substances of foodborne pathogenic and spoilage bacteria: A review. Foods, 12(16), 3128. https://doi.org/10.3390/foods12163128