A FILAMENTOUS BACTERIOPHAGE FROM XANTHOMONAS ORYZAE

Xf, a newly isolated filamentous bacteriophage of Xanthomonas oryzae is described. Morphologically Xf is very similar to filamentous coliphages, but it differs from them in host specificity, base composition in their DNA, and sensitivity to treatment with chloroform and sodium lauryl sulfate. The phage is a filamentous one, about 9768 Å in length and 84 Å in width. The host specificity of Xf is wider than that of coliphage. Xf infects 16 strains of X. oryzae, whereas coliphages infect only male strains of Escherichia coli. X. oryzae does not seem to have pili, which exist in male strains of E. coli and are believed to be a specific site of attachment for coliphage. The infection of Xf does not depend on these specific sites of attachment for coliphage. This may be why Xf has a wider host specificity. The phage can support a wider range of mechanical stresses and withstand high temperature; it is resistant to treatment with DNase and trypsin, but very sensitive to chloroform and sodium lauryl sulfate. On the basis of noncomplementary base ratio, the pattern of melting curve or change in ultraviolet light absorption upon heating, formaldehyde reaction, and precipitation by metal ion, Xf DNA is characterized as single-stranded. The base composition of Xf DNA is thymine 19.3%, guanine 32.6%, adenine 20.6%, and cytosine 27.5%. © 1969.