First report on characterization of citrus disease causing bacteria and related phages isolated in Pakistan

Abstract

Bacteriophages that infect specific bacteria are relatively common. Specific bacteriophages are proving to be the potential alternate to conventional bactericides used to combat certain phytopathogens that are ruining economically significant fruit crops. This study aimed to isolate and characterize the citrus disease causing bacteria and associated bacteriophages analyzing their ability to impact these specific bacteria. Morphological, biochemical and molecular characterization of seed bacteria were performed and identified isolates were subjected to custom sequencing of partial 16S ribosomal DNA to understand their phylogeny. The morphological characteristics of bacterial strains were Gram-negative rods that grew as obligate aerobes on YPGA medium. Results of biochemical analysis showed that the bacterial strains were oxidase negative and catalase positive. Phage screening and isolation was done by co-culturing the phage and host bacteria. The isolated phages were characterized by plaque assay, spot assay and broth clearance of bacterial cultures. The effect of these phages on bacterial virulence was evaluated by infecting citrus leaves with bacterial strain and subsequent application of phage suspension.