Differences in the genetic structure of Bacillus subitilis strains carrying the trpE26 mutation and strain 168.

It was previously shown that in strains of Bacillus subtilis bearing the trpE26 mutation a chromosome segment (from trpD to ilvA) is translocated to a position near the thr region. Further PBS1-mediated transduction data have now revealed that these strains also possess an inversion of part of the chromosome from the origin of replication, down to the tre locus on one side and the cysB locus on the other. These data concern evidence of linkage of tre-12- to markers in the translocation (hisH2, tyrA1, and metB3) as well as linkage of the cysB3 marker to thi-86, gly-133, and catA. They explain the previously observed absence of linkage of markers in the translocated segment to cysB3. The model proposed for the formation of merodiploids in trpE26 strains, which calls for the fusion of two genetic elements, is not incompatible with this new finding.