Abstract: Disclosed are novel bacterial hosts that are capable of high efficiency transformation with methylated and/or unmethylated nucleic acids, and that are bacteriophage resistant. Such bacteria contain: (1) an F? episome that confers high efficiency transformability; (2) one or more mutations that allow transformation of methylated nucleic acids; (3) one or more mutations that allow transformation with unmethylated nucleic acids; and/or (4) one or more mutations that confer resistance to bacteriophage infection. Also disclosed are methods for transforming such bacteria, and kits that contain such bacteria (e.g., that have been made competent for transformation).

Abstract: This invention relates to a method for producing cells which are competent for transformation and which may be stably stored for extended periods of time at various temperatures. The method involves growing cells in a growth conducive medium, rendering said cells competent, and lyophilizing said competent cells. The invention further relates to competent cells produced by such a method, to methods of transforming said cells with a DNA molecule, and to a method of producing a desired protein or polypeptide from said transformed cells.