Kinetics of Thermal Destruction of Bacteriophages Active Against Streptococcus lactis

Abstract

The kinetics and thermodynamics of the heat inactivation for bacteriophages active against Streptococcus lactis C2 and C10 were determined in skimmilk. Thermal destruction of Phage c10 at 55, 60, and 65C and Phage c2 at 55C followed the kinetics of a first-order reaction. However, at 60 and 65C, the thermal destruction of Phage c2 failed to follow the kinetics of a first-order reaction. At 60.2C, the rate of heat inactivation of Phage c10 and the second component of Phage c2 was the same. The D, k, and ΔF values for Phage c2 would indicate that it is more heat stable above 60.2C and less heat stable below 60.2C than c10 phage. Based on the high positive Ea and ΔS values, it would appear that protein and nucleic acid denaturation is associated with the thermal inactivation process for Phage c10. In contrast, for Phage c2, low positive Ea and negative ΔS values indicate that the thermal inactivation of this phage at the temperatures studied involves a single point of attack of the deoxyribonucleic acid strand or a disorientation of a decisive protein.