Effect of Infection with Filamentous Phage Xf on the Growth, Ultrastructure and Virulence of Xanthomonas campestris pv. oryzae N5850

Abstract

Effect of infection with filamentous phage Xf on the growth, ultrastructure and virulence of Xanthomonas campestris pv. oryzae N5850 was investigated. The growth of Xf-infected bacteria was considerably retarded at 30C as compared with that of uninfected bacteria. The Xf-infected bacteria, however, rapidly multiplied from 36hr after infection to almost the same level of concentration as reached by uninfected cells after 72hr of incubation. The infected bacteria could grow even at 35C to some extent, while uninfected bacteria could not. Electron microscopic observation of the ultrathin sectioned Xf-infected bacteria grown at 30, 33.8 and 35C revealed that a number of vesicles exist on the cell surface. Some remarkable changes in the intracellular structures, viz., lack of uniformity in distribution of both ribosomes and fibrils in nucleoid area were observed in the Xf-infected bacteria. Xf-infection caused the bacteria to produce a greater amount of extracellular polysaccharide and to increase virulence.