The pAMJ2006 replicon is similar to the replicon of the citrate plasmid pCT1138A from L. lactis subsp. lactis biovar., which is a medium copy-number plasmid (Pedersen et al., 1994). In contrast, the pAMJ2008 replicon originated from the high copy-number Enterococcus faecalis pAMb1 replicon (Clewell et al., 1974). Transformation of E. coli was conducted using the Inoue method (Inoueet al., 1990). L. lactis MG1363 was transformed by electroporation, as described by Holo and Nes (1989).