Selection for restriction-induced in vivo deletion in phage vector phi 1E1 of Bacillus subtilis

Recombinant phage phi 1E1metB, which contains the 4.5-kb EcoRI fragment of Bacillus subtilis DNA, has no HaeIII cleavage sites within the vector phi 1E1 genome but only in the metB insert. When phi 1E1metB was grown in B. subtilis ISR11, which produces BsuR, the isoschizomer of HaeIII, it was restricted and survived with an efficiency of approx. 10(-5). All the survivors were deletion mutants of phi 1E1metB, and only various segments of the insert DNA delineated by HaeIII sites were deleted. The Met+ transforming activities of the DNAs from phi 1E1metB and its deletion derivatives were examined, and the restriction maps of the deletion mutants were correlated with five metB- mutation sites.