Molecular analysis of two rolling-circle replicating cryptic plasmids, pBMYdx and pBMY1, from the soil gram-positive Bacillus mycoides.

Two cryptic plasmids of two environmental strains of the soil Bacillus mycoides were cloned and sequenced. They are of a small size (3377 and 3476 bp) and carry regions homologous to double- and single-strand origins of replication of rolling-circle replication modules. In addition, both plasmids have ORFs with homologies with Mob and Rep proteins, in the same relative position and orientation. While dso- and sso-like sequences are similar in pBMY1 and pBMYdx, the putative Mob and Rep proteins are not homologous between the two but show similarity with Mob and Rep proteins of different bacterial plasmids.