Characterization of new Myoviridae bacteriophage WZ1 against multi-drug resistant (MDR) Shigella dysenteriae

Shigella dysenteriae is a normal inhabitant of the human gastrointestinal tract, but sometimes it causes severe infection known as shigellosis (bacillary dysentery). Bacteriophages are considered very safe and effective agents for controlling bacterial infections and contaminations. In this study, we describe the isolation and characterization of bacteriophage WZ1, isolated from waste water which inhibits the growth of S. dysenteriae. Phage WZ1 showed maximum stability at 37 degrees C and was stable up to 65 degrees C but was totally inactive at 70 degrees C. The pH stability increased from low to high and was totally inactive at pH 3 while maximum stability was observed at optimal pH 7. Phage WZ1 adsorption rate to the host bacterium was significantly enhanced by the addition of CaCl2. It has a latent time and burst time of 24min and about 430 virions/cell, respectively. Transmission electron microscopy of phage WZ1 revealed a head width of 10 +/- 0.5nm and length of 10 +/- 0.2nm with a contractile tail of 128 +/- 25nm long and 21 +/- 0.5nm wide and belongs to family Myoviridae of order Caudovirales. Twelve structural proteins ranging from 22 to 150kDa were detected by Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). The genome was found to be double stranded DNA with an approximate size of 38kb. It has a very good reduction potential for S. dysenteriae by lowering abruptly the optical density of the planktonic S. dysenteriae culture. Phage WZ1 is a very promising candidate for phage therapy and other applications such as phage typing.