Isolation and characterization of a generalized transducing phage for Xanthomonas campestris pv. campestris

We have isolated and characterized a lytic double-stranded DNA Xanthomonas campestris pv. campestris bacteriophage (XTP1) capable of mediating generalized transduction. The phage transduces chromosomal markers at frequencies of 10^-5 to 10^-6 transductants per PFU. We demonstrated its genetic utility by the isolation and cotransduction of linked transposon insertions to a nonselectable locus, xgl, required for the cleavage of 5- bromo-3-chloro-indoyl-β-D-galactoside and showed that rif and str alleles in X. campestris are 75% linked. One-step growth experiments showed that the latent and rise periods were each 2 h and the average burst size was 35. The DNA genome is approximately 180 kb, presumably modified in a sequence- specific manner, and may be covalently attached to protein(s). Electron micrographs show the phage particle to have an icosahedral head and contractile tail with tail fibers uniquely attached to a location 40 nm proximal from the end of the tail.