Characterization of lytic bacteriophage XCC9SH3 infecting Xanthomonas campestris pv. Campestris

Abstract

Soil and plant samples from black rot infected fields were processed to isolate wild type Xanthomonas campestris pv. campestris (Xcc) bacteriophages by overlay agar method. Various Xcc strains were employed as indicator hosts. The aim of this study was to isolate and purify potential bacteriophages for their ability to lyse plant pathogenic strains of Xcc in vitro. Bacteriophages were purified and selected for further characterization based on their ability to produce clear lysis on plaque assay. Seventeen strains of pathogenic Xcc were tested for sensitivity to 31 phages isolated during the study. Lysis was graded subjectively as per standard. A virulent phage Xcc9SH3 isolated from soil sample from Lucknow was found to lyse all tested strains of Xcc in vitro. Characterization of Xcc9SH3 was done based on plaque morphology, phage titre, organic solvent sensitivity, effect of temperature and transmission electron microscopy. The size of long noncontractile tail of the phage was 100 nm in length and 10 nm in width with 20 nm diameter of head. The isometric head of the phage predicted to belong to Siphoviridae (dsDNA viruses) family of bacteriophages. These phages may be useful tool in specific and efficient detection and control of Xcc causing black rot disease in cole crops.