Application of R-plasmid DNA’s fromEscherichia coli minicells in genetic transformation

Abstract
Components of minicell lyzatesof Escherichia coli P678-54 (Rldrd19) andEscherichia col P678-54 (R6K) were visualized in an electron microscope and used for the transformation ofEscherichia coli JC7623. The frequency of the resulting transformants (of the order of 10−6 %) was not appreciably influenced by the manner of lyzate preparation. The presence of covalently closed circular DNA was detected in two different transformants using radioisotopes, thus demonstrating an autonomous existence of Rldrd19 or R6K plasmids in tested transformants. This finding corresponds with the results of their genetic analysis.