FIGURE 3.

Thermal and pH stability of Shigella phage SFPH2. S. flexneri 2a strain SF2 was used as the host. (A) Thermal stability test. Phage SFPH2 preparation (1 × 10¹⁰ Pfu/ml) was incubated at 37, 50, or 70°C for 24 h. (B) PH stability test. Phage SFPH2 at 1 × 10¹⁰ Pfu/ml was incubated at pH 2–13 for 24 h. All the samples of these two tests were taken at 1, 3, 6, 9, and 24 h time-points and the phage titer was determined using the double-agar-layer method.