HIGH-FREQUENCY, SITE-SPECIFIC RECOMBINATION BETWEEN LACTOCOCCAL AND PAM-BETA-1 PLASMID DNAS

In vivo recombination events involving the 75-kilobase lactose proteinase plasmid pCI301 of Lactococcus lactis subsp. lactis UC317 and the conjugative enterococcal plasmid pAMβ1 were analyzed. A fragment, identified as containing the pCI301 recombination site, mediated greatly elevated levels of mobilization and recombination with pAMβ1 when cloned in a nonmobilizable L. lactis-Escherichia coli shuttle vector. This latter recombination event was site an orientation specific on both plasmids. Recombination on pAMβ1 was within the region associated with plasmid replication, but no effect on pAMβ1 replication functions was detected. Resolution of recombinant plasmids generated derivatives indistiguishable from the parental plasmids.