DEFINITION OF A DURATION THRESHOLD IN THE 1ST STEP FOR ENERGY TRANSDUCTION BY ESCHERICHIA-COLI BY USE OF A MICROSECOND ELECTRIC-FIELD PULSE

The total ATP content increased in Escherichia coli when the bacteria were submitted to square wave electric pulses with field intensities o f about 1 kV/cm and duration larger than 20 mus. Nothing was observed when duration was shorter. The transduction of energy from its electri cal form (membrane potential) to another, stored in the membrane which was converted later in the terminal P bond of ATP, required a key-ste p which had to last for more than this threshold of 20 mus. Square wav e electric-field pulses appeared as a new non-invasive approach for th e determination of the kinetics of fast energy-transduction events.