A rapid and economic method for estimation of the number of plasmid copies in Escherichia coli cells.

An economic method for a rapid estimation of the number of copies of plasmid R6K delta 1 in E. coli cells using lysis of the cells directly on the agarose gel and electrophoretic separation of radioactively labelled plasmid and chromosomal DNA's is described. The method, particularly useful for screening purposes, permits detection of both the CCC and OC forms of plasmids of molar mass 2-150 Mg/mol and it can be applied to other bacterial systems.