VIABLE DELETION MUTANTS OF BACILLUS SUBTILIS PHAGE ρ 11

Abstract

When DNA from .rho. 11c3, a clear mutant of temperate phage .rho.11, was digested with the restriction endonuclease BamHI and the products were analyzed by agarose gel electrophoresis, there appeared 8 distinct fragments which could be designated as BamHI A-H in order of decreasing size. To study the order of their arrangement on the .rho.11c3 DNA, many plaque-forming deletion mutants were isolated from .rho.11c3 and compared with .rho.11c3 on BamHI cleavage pattern in agarose gels. The arrangement was tentatively determined as D-G-E-C-A-(F-H)-B. The thymidylate synthetase gene in the .rho.11 genome was found to reside on the fragment A. It was found, from studies of .rho.11c3 deletion mutant DNAs that deletions in the D-G-E region and the C region gave no lethal effect on the phage.