Microbiological implications of electric field effects VII. Stimulation of plasmid transformation of Bacillus cereus protoplasts by electric field pulses

The aim of this study was to check the action of electric field pulses (1) on the survival of intact cells and protoplasts of Bacillus cereus and (2) on the transformation frequency of these protoplasts with plasmid DNA from Bacillus thuringiensis transformants. – B. cereus cells and protoplasts are very resistant to high electric field pulses in the microsecond range. The transformation frequency of B. cereus protoplasts with plasmids from B. thuringiensis (pUB 110) can be increased by about one order of magnitude with the electric field pulse technique. The transformants are stable and pUB 110 is preserved as an extrachromosomal element.