Evidence for the conjugal transfer of the broad host range plasmid pIP501 into strains ofLactobacillus helveticus

摘要

The conjugative broad host range plasmid pIP501 was transferred fromStreptococcus faecalisto a series of strains of lactic streptococci used commercially as dairy starter cultures. With these transconjugants as donors the plasmid was exconjugated to two strains ofLactobacillus helveticusand a commercially used strain ofStrep, thermophilus.There was evidence that the plasmid could transfer between isogenic derivatives of one of the strains ofLact. helveticus.Transfer fromLact. helveticustoStrep. faecaliswas also detected but at a low frequency. There was no evidence for the conjugal transfer of plasmid pIP501 into a strain ofLact. bulgaricusby exconjugation from either lactic streptococci orLactobacillussp.