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It was found that plasmid DNA(PUB 110) can be introduced into not only protoplasts but also intact cells of Bacillus subtilis by electric field pulses. The transformation of, B. subtilis using protoplasts results in an efficiency of 2.5 x 104 transformants per /ig of DNA,with a single pulse of 50 jisec with an initial electric field strength of 7 kV/cm. Even transformation of intact B. subtilis cells results in a maximumefficiency of 1.5 x 103 transformants per /ig DNA,with a single pulse of 400 /isec with an initial electric field strength of 16 kV/cm. The cell survival of protoplasts and intact cells was approximately 100% and 30%, respectively, under the conditions found to be optimal for the transformation process. Plasmid DNA isolated from PUB 110 containing transformants was indistinguishable from authentic preparations of PBU110 on gel electrophoretic analysis. Electroporation involves the application of high-intensity electric fields of a short duration (pulse length) to reversibly permeabilize biomembranes. This technique is commonlyused to transfer DNA into mammalian cells,1~6) and applications to plant protoplasts7~9) and yeast10'11} have been reported. Recently, electrical impulses have also been used for the transformation of prokaryotic cells with plasmid DNA. Shivarova et al.12) reported that the transformation frequency, 1.1 x 10~3, for Bacillus cereus protoplasts in the pres

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