ISOLATION AND CHARACTERIZATION OF A GENERALIZED TRANSDUCING PHAGE FORXANTHOMONAS-CAMPESTRIS PV CAMPESTRIS

We have isolated and characterized a lytic double-stranded DNA Xanthom onas campestris pv. campestris bacteriophage (XTP1) capable of mediati ng generalized transduction. The phage transduces chromosomal markers at frequencies of 10(-5) to 10(-6) transductants per PFU. We demonstra ted 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-beta-D-galactoside and showed that rif and str alleles in X campestris are 75% linked. One-step growth e xperiments showed that the latent and rise periods were each 2 h and t he average burst size was 35. The DNA genome is approximately 180 kb, presumably modified in a sequence-specific manner, and may be covalent ly attached to protein(s). Electron micrographs show the phage particl e to have an icosahedral head and contractile tail with tail fibers un iquely attached to a location 40 nm proximal from the end of the tail.