title: Prolonged incubation in calcium chloride improves the competence of Escherichia coli cells.
abstract: Escherichia coli cells are 4--6 times more transformable and 20--30 times more competent after 24 h incubation in cold calcium chloride than immediately after calcium chloride treatment. With 24-h-old competent cells we obtained routinely 2 . 10(7) transformants per microgram of pBR322 DNA, and transformed over 20% of viable cells.
mesh_terms: D002122:Calcium Chloride / Q000494:pharmacology*; D003080:Cold Temperature; D004926:Escherichia coli / Q000235:genetics*; D010957:Plasmids; D013997:Time Factors; D014169:Transformation, Bacterial / Q000187:drug effects*
chemical_list: D002122:Calcium Chloride