Application of Bacteriophages as Biological Control Agents for Escherichia coli in Milk

Bacteriophages have attracted attention due to their unique abilities in controlling microbial contamination and maintaining the quality of food products. The stability of phages against changes in pH and temperature plays a significant role in their applications in the food industry and public health. This study evaluates the pH and thermal stability of bacteriophage PhE۸ and its role in reducing the microbial load in milk contaminated with Escherichia coli at two temperatures of ۴°C and ۲۵°C. The stability of bacteriophage PhE۸ against pH and heat was measured. The activity of the bacteriophages was assessed using Plaque Forming Unit (PFU). To investigate the antimicrobial activity of PhE۸, ۵ ml of pasteurized milk was treated with ۱۰۰ µl of Escherichia coli (E۸) bacteria along with ۱۰۰ µl of phage suspension. The samples were stored for four days at ۴°C and ۲۵°C. Electron microscopy revealed that the isolated phage has a polyhedral head and a contractile tail. The latent period was ۱۰ minutes. Phage PhE۸ was stable within the pH range of ۴ to ۱۲ and remained stable at temperatures between ۳۰°C and ۶۰°C for ۳۰ minutes. The studied phage demonstrated high potential in reducing the microbial load in milk at ۴°C. The high stability of the phage at normal pH and its significant decrease in activity at high temperatures provide useful information for the practical use of phages in real-world conditions.

کلیدواژه ها:

Food Industry ، Bacteriophage ، Biological preservatives ، Escherichia coli ، Phage