Filamentous Phages Released from Xanthomonas campestris pv. citri

Abstract

Two kinds of filamentous phage, named XCf1, and XCf2, were found to be released from the living cells of Xanthomonas campestris pv. citri isolates and some of their properties were investigated in comparison with X. campestris pv. oryzae phages Xf and Xf2.
The phages XCf1 and XCf2 were releaed from the bacterial isolates N 6101-1 and N 6107, respectively and they could attack only X. campestris pv. citri isolates. They multiplied in a liquid medium in parallel with bacterial multiplication to reach maximum concentration at about 10⁵ PFU/ml. The phages XCf1 and XCf2 were similar in particle length ranging from 800 to 1100 nm. Both phages were heat resistant and survived even the treatment at 80 C for 10 min, but inactivated by the treatment with organic solvents such as chloroform, methyl alcohol, ethylether and acetone.
Serological inactivation tests revealed that both phages were closely related each other. Anti-XCf1 serum readily inactivated the phage Xf, but anti-Xf serum did not inactivate the phage XCf1, suggesting some relationship between the two. The phage XCf2 showed very slight serological relationship with Xf but not at all with Xf2.
Ten isolates of X. campestris pv. citri out of 33 tested released XCf1 and 4 released XCf2.