Southern blot hybridization of E. faecalis chromosomal DNA digested with EcoRI. The probe corresponded to pAM3329 carrying an internal segment of eep. Lane 1, OG1X; lane 2, FA3328 (eep mutant); lane 3, FA3329 (eep mutant); lane 4, FA3328R; lane 5, FA3329R; lane 6, pAM3329.