Molecular evidence for a new bacteriophage of Borrelia burgdorferi

We have recovered a DNase-protected, chloroform-resistant molecule of DNA f rom the cell-free supernatant of a Borrelia burgdorferi culture. The DNA is a 32-kb double-stranded linear molecule that is derived from the 32-kb cir cular plasmids (cp32s) of the B. burgdorferi genome. Electron microscopy of samples from which the 32-kb DNA molecule was purified revealed bacterioph age particles. The bacteriophage has a polyhedral head with a diameter of 5 5 nm and appears to have a simple 100-nm-long tail. The phage is produced c onstitutively at low levels from growing cultures of some B. burgdorferi st rains and is inducible to higher levels with 10 mu g of 1-methyl-3-nitroso- nitroguanidine (MNNG) ml(-1). In addition, the prophage can be induced with MNNG from some Borrelia isolates that do not naturally produce phage. We h ave isolated and partially characterized the phage associated with B. burgd orferi CA-11.2A. To our knowledge, this is the first molecular characteriza tion of a bacteriophage of B. burgdorferi.