Isolation,Purification and Physiological Characteristics of Microviridae Bacteriophage αα with a Broad pH Resistance

A novel lytic Salmonella bacteriophage(hereafter refer to as phage),named αα was isolated from sewage samples via the overlay method. The morphology of phage αα was checked via transmission electron microscope(TEM)and its nucleic acid composition was checked via agarose gel electrophoresis. In addition,the physiological characteristics of phage αα were also determined,including one-step growth curve,temperature stability,pH stability,host range,optimal ion concentration and optimal multiplicity of infection(MOI)in the liquid proliferation. As a result,the electron micrograph revealed that phage αα was 20 nm in diameter and had no tail,and its nucleic acid was a single-stranded DNA,which proved it to belong to Microviridae family. Phage αα had no significant latent period and the lysis time was 60 min. For pH and thermal stability,it showed that titers of phage αα could be 10⁶~10⁸ pfu/mL with pH varied from 2.10 to 11.45,and 10⁸ pfu/mL between 40 to 50 ℃ in temperature. In the liquid proliferation,on the one hand,the optimal MOI was 10^-4,showing its strong multiplicity. On the other hand,magnesium could facilitate the proliferation of αα,and adding 10 mmol/L MgCl₂ had a best effect on the liquid proliferation. The results laid a foundation for the study of phage diversity and its application.