Abstract—Antimicrobial resistance has rekindled interest in bacteriophages, viruses that specifically infect and lyse bacteria. Understanding phage viability under various conditions is vital for assessing their potential applications across industries and for developing effective phage control measures. This study investigates the thermal inactivation kinetics of the T4 bacteriophage at different temperatures. Samples of T4 phage were exposed to 55°C, 60°C, and 70°C, with constant agitation at 200 RPM. The inactivation process followed a first-order kinetic model, which was used to determine the rate constants (k) and activation energy (Eₐ). The rate constants were calculated as −0.004485 ± 0.001466, −0.01323 ± 0.001546, and −0.05356 ± 0.01161 min⁻¹ at 55°C, 60°C, and 70°C, respectively. The activation energy (Eₐ) was found to be 151.92 kJ/mol, confirming the thermal stability of T4 within this temperature range. High positive free energy of inactivation (ΔG) and negative entropy (ΔS) values further indicated the structural and ordered thermo-stability of T4. The study highlights significant thermal inactivation at elevated temperatures, with rapid inactivation occurring at 70°C. These findings not only underscore the importance of understanding thermal inactivation kinetics for bacteriophage stability but also provide valuable insights for optimizing their use in industrial applications and informing effective phage control strategies across various environments.

Keywords—Bacteriophage T4, thermal inactivation, kinetic model, inactivation thermodynamics