CHARACTERIZATION OF FILAMENTOUS BACTERIOPHAGE-PHI-LF FROM XANTHOMONAS-CAMPESTRIS PV CAMPESTRIS

A filamentous phage, ΦLf, which specifically infects Xanthomonas campestris pv. campestris was isolated. The phage particle measured 1000 (± 200) x 8 nm. It formed turbid plaques of about 1 mm in diameter. During multiplication, the progeny virions extruded into the medium without retarding host cell growth. Stocks were stable for 6 months at 4°C and survived treatment at 80°C for 10 min. Treatment with chloroform, ethanol or acetone completely destroyed infectivity; ethyl ether and methanol inactivated 98 to 99% of the phage. SDS-polyacrylamide gel electrophoresis showed a major coat protein band of approximate M(r) 4000 whereas an immunoprecipitation test detected the existence of two coat protein species. The phage genome was shown to be a single-stranded DNA molecule. A physical map was constructed and the DNA size was calculated to be 5.9 kb. Cells treated with Tris-HCl containing CaCl2 and polyethylene glycol 6000 were transfected by replicative form DNA at a frequency of 3.4 x 103 p.f.u./μg.