Identification, cloning and sequencing of the replication region ofLactococcus lactisssp.lactisbiovar. diacetylactis Bu2 citrate plasmid pSL2

The replication region of the 7.8 kilobase (kb) citrate plasmid pSL2 from Lactococcus lactis ssp. lactis biovar. diacetylactis Bu2 was identified. Deletion derivatives of pSL2 were introduced into plasmid-free strain Bu2-60 and tested for their ability to replicate autonomously. The region necessary for replication was identified by comparison of the pSL2 derivatives, cloned and sequenced. No homologies were detected by comparing the putative Rep protein of pSL2 with replicons of other plasmids of Gram-positive bacteria. A part of an IS-element flanking the replication region was found.