VIABLE DELETION MUTANTS OF BACILLUS-SUBTILIS PHAGE-RHO-11

When DNA from ρ11 c3, a clear mutant of temperate phage ρ11, was digested with the restriction endonuclease BamHI and the products were analyzed by agarose gel electrophoresis, there appeared eight distinct fragments which could be designated as BamHI A-H in the order of decreasing size. To study the order of their arrangement on the ρl1c3 DNA, many plaque-forming deletion mutants were isolated from ρ 11 c3 and compared with ρl1c3 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 ρll genome was found to reside on the fragment A. It was found, moreover, from studies of ρllc3 deletion mutant DNAs that deletions in the D-G-E region and the C region gave no lethal effect on the phage. © 1979, Applied Microbiology, Molecular and Cellular Biosciences Research Foundation. All rights reserved.