Articles
EVIDENCE THAT DERIVATIVES OF THE BACTERIOPHAGE MU CAN BE USED AS GENETIC TOOLS IN ERWINIA AMYLOVORA
The Mu genome contains a region, called G, that can invert.
Each orientation of this DNA fragment corresponds to the synthesis of different proteins involved in the host specificity of the viral particle.
The two different kinds of particles are called Mu G(+) and Mu G(-) according to the orientation of the G fragment in the Mu DNA.
When Mu cts 62 lysates, containing both Mu G(+) and Mu G(-) particles, were spotted onto a double layer seeded with E. amylovora, strain 1430, inhibition zones arose after incubation at 30°C. Further analysis showed that these inhibition zones contained Mu particles, indicating that Mu can multiply in this strain of E. amylovora. Viral suspensions made from these inhibition zones contained approximately 1000-fold more Mu G(-) particles than Mu G (+), leading to the conclusion that strain 1430 is sensitive to Mu phage having the G(-) host range.
Surviving colonies were isolated from Mu plaques obtained with E. amylovora 1430 used as an indicator strain.
These colonies released infectious Mu particles.
Furthermore, the autoradiogram from Southern blot hybridization using Mu cts 62 DNA as a probe shows that these strains contained a Mu cts 62 prophage in the genome.
These results were corroborated using Mu derivatives carrying an antibiotic resistance marker.
Using several Mu or mini Mu derivatives, lysogenic clores of 1430 were recovered on a medium