Biological properties of the filamentous phages released from Xanthomonas oryzae isolates

Two kinds of filamentous phage were found to be released from Xanthomonas oryzae isolates and some of their properties were made clear. The filamentous phage released from X. oryzae N5828 was identified as Xf which was reported by Kuo in 1967, because they were identical in host range, plaque morphology, and serological and morphological properties. The phage released from the bacterial isolate N5845, however, is quite different from Xf. The name proposed is Xf2. The host range of phage Xf2 is very narrow as compared to that of Xf. Neither phage can attack any other xanthomonads tested. The modal length of Xf particles is 965nm, while that of Xf2 is 1573nm. Both phages remained mostly intact after heat treatment at 60C for 60min. Phage Xf is sensitive to chloroform, methyl alcohol and acetone, but not to ethylether, whereas Xf2 is sensitive to ethylether and more sensitive to chloroform than Xf. Twenty-six isolates of X. oryzae out of 50 tested released Xf2 and three released Xf, while one isolate, N5804, released both Xf and Xf2 simultaneously.