Intergeneric and intrageneric conjugal transfer of plasmids pAMβ1, pIL205 and pIP501 inLactobacillus sake

Abstract

Transfer of the broad host range conjugative plasmids pAM β 1, pIP501 and its derivative pIL205 into Lactobacillus sake was studied. Frequencies up to 5 × 10−6 transconjugants per recipient cell were found from Lactococcus lactis strain IL1403 to various strains of L. sake. The transfer takes place by a conjugation‐like process on solid surface agar. Intrageneric transfer between L. sake strains was also observed, although at lower frequencies (10−7 transconjugants per recipient cell). The ability to transfer these plasmids into L. sake strains which are either refractory to transformation or poorly transformable provides a method of genetic transfer, thus opening the way for cloning strategies developed in other Gram‐positive bacteria.