Isolation and Characterization of Two Bacteriophages Infecting Kosakonia sacchari Bacterium Causing Potato Soft Rot Disease

Potato crop is one of the most economically important crops, and is considered as the fourth main food crop in the world. One of the most important serious diseases of potato is bacterial soft rot disease. In our study, soil samples were collected from potato rhizosphere from a potato cultivated field in Giza, Egypt. Two bacteriophages were isolated on Kosakonia sacchari as a host, causing potato soft rot disease. Based on the genome characterization and electron microscopy, the two phages were named as vB_KsaM-C1 belonging to Myoviridae and vB_KsaO-C2 belonging to Microviridae. Both phages sustained their activity more than 20 months with a remarkable decrease in phage titre. In addition both recorded the same TIP at 65°C and showed the optimum activity at pH 7. The DEP of vB_KsaM-C1 was 10-7, while that of phage vB_KsaO-C2 was 10-9. A small scale application of the two isolated bacteriophages on infected potato tubers discs, in the lab, successfully inhibited bacterial soft rot caused by Kosakonia sacchari.