Characterization of two psychrophilic Pseudomonas bacteriophages isolated from ground beef

Characterization studies were performed on two psychrophilic phages which were isolated from ground beef samples. Phage inactivation by exposure to heat, low pH, osmotic shock conditions, and freezing showed that these two isolates were different. One-step growth experiments indicated that one isolate had a burst size five times as large (500) and a latent period two times as long (4 hr) as the other when tested at 7 C. Nucleic acid type was 2-deoxyribonucleic acid for both. Electron micrographs showed one to belong to Bradley's phage group A and the other to phage group C.