ISOLATION AND CHARACTERIZATION OF VIRULENT PHAGES INFECTING Bacillus megaterium

Ten bacteriophages specific for Bacillus megaterium were isolated from rhizosphere soil of wheat plants growing in the research farm at Faculty of Agriculture, Sohag University, Sohag, Egypt. To characterize these phages, optimum pH, host specificity for infection, thermal inactivation point, sensitivity to UV-radiation, longevity in vitro and morphology were tested. The isolated phages were found to be resistant to alkaline and acidic reactions. All phage isolates showed three distinct host specificities. Five of them were discovered to be infectious to B. subtilis. Two phages coded as 4 and 8 were found to be infectious to B. licheniformis. Moreover, the other three phages (1, 2 and 6) were found to be infectious to the host bacteria (Bacillus megaterium). Based on their characteristics, ten phage isolates were divided into four groups coded as A, B, C and D. Each group's phages shared similar optimal pH for infection, host specificity, thermal inactivation point, UV sensitivity, in vitro stability, particle size and morphology. To make it easier to describe, naming of the four phage groups as empty setSP1, empty setSP2, empty setSP3, and empty setSP4 was respectively suggested based on their characteristics.