A novel Bacillus natto plasmid pLS32 capable of replication in Bacillus subtilis.

Plasmid pLS32 is a relatively large (approximately 70 kbp), cryptic, low copy-number plasmid present in Bacillus natto. We isolated and analyzed the replication region of the plasmid in B. subtilis, and the following results were obtained: the replication region contained an open reading frame encoding a 287-amino acid protein (RepN), whose amino acid sequence was partially homologous with those of the Rep proteins encoded on plasmids pAD1 and pLJ1 isolated from Enterococcus faecalis and Lactobacillus helveticus, respectively; the replication origin (oriN) was located in the repN-coding region; the copy number of a pLS32 derivative, pBET131, was 2 to 3 per chromosome; replication of pBET131 required poll. These features show that pLS32 is a novel plasmid capable of replication in B. subtilis.