Comparison of Plasmid Transformation and the Cloning of Recombinant DNA in Streptococcus Pneumoniae and Bacillus Subtilis

摘要

The molecular cloning of the malM gene of Streptococcus pneumoniae in a strain of S. pneumoniae bearing a deletion of the chromosomal mal region enabled us to investigate the feasibility of recombinant DNA cloning also in the presence of chromosomal homology. Encouraged by the information so obtained, we then inserted chromosomal fragments into pLS1, a miniplasmid derivative of the pMV158 vector used for the mal cloning, in its single EcoRI restriction site. In this manner the sul-d gene responsible for sulonamide resistance was cloned. The availability of the mal recombinant plasmid also allowed a comparison between plasmid transfer, that is the establishment of a new plasmid, the plasmid transformation, that is the alteration of a homologous endogenous plasmid, in S. pneumoniae. These findings were related to published work by others on plasmid transfer and transformation in S. pneumoniae and Bacillus subtilis. In both species the results are consistent with a mode of DNA entry in which single strand fragments of donor DNA are introduced into the cell. Models for the subsequent reconstruction of plasmid and recombinant DNA are presented. (ERA citation 06:029293)