Physical mapping of multiple homologous genes in the bacillus subtilis 168 chromosome: identification of ten ribosomal rna operon loci

Ten ribosomal RNA operons (rrn) of the Bacillus subtilis 168 strain were precisely located in the complete physical map, i.e., the NotI and SfiI restriction map [M. Itaya and T. Tanaka, J. Mol. Biol., 220, 631–648 (1991)]. Mapping was done by identification of the NotI and the SfiI fragments to which the rrnO operon hybridized. This protocol proved that homologous multiple genes dispersed on the chromosome can be physically mapped by using a single membrane filter. A previously unidentified deletion formation was shown to be that caused by homologous recombination between rrnJ-W.