Isolation of a DNA sequence related to several plasmids from Bacillus thuringiensis after a mating involving the Streptococcus faecalis plasmid pAMβ1

Abstract

The transmissible plasmid pAMβ1, which codes for resistance to erythromycin and lincomycin, was transferred from Streptococcus faecalis to several strains of Bacillus thuringiensis by a filter-mating process. Introduction of pAMβ1 into the Em^r transconjugant strains of B. thuringiensis was confirmed by Southern hybridisation using the ³²P-labelled pAMβ1 as a probe. In the B. thuringiensis transconjugant strains, used as donors, the β plasmid conserved its ability to be transferred during intraspecific mating, with a frequency of 10^-4 per recipient cell. In addition, the transconjugant clones acted as donors of the erythromycin resistance marker and permitted the transfer of cryptic plasmids present in the B. thuringiensis (β) strains used as donors. From a transconjugant clone of B. thuringiensis a hybrid plasmid resulting from an in vivo insertion into pAMβ1 of a 3 Md DNA sequence was isolated. This 3 Md DNA molecule originated from a 54 Md plasmid of a kurstaki strain and is related to several plasmids found in different serotypes of B. thuringiensis.