Abstract
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 × 104 transformants per μg of DNA, with a single pulse of 50 μsec with an initial electric field strength of 7 kV/cm. Even transformation of intact B. subtilis cells results in a maximum efficiency of 1.5 × 103 transformants per μg DNA, with a single pulse of 400 μsec 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 pBU 110 on gel electrophoretic analysis.
