Inactivation of Bucillus Stearothermophilus by pulsed electric field

B. Stearothermophilus remains alive even under intense electric field, since spores formed are highly resistant to damage from electric field effects. This paper describes the effects of pulsed electric field on B. Stearothermophilus (ATCC no, 12980). An aqueous suspension of B. Stearothermophilus spores was placed between parallel planar electrodes and subjected to pulsed electric fields of up to 189 kV/cm, which are obtained from a high-voltage pulsed voltage generator. Either a Blumlein generator or a magnetic compression circuit with a semiconductor opening switch was used as the pulsed voltage generator. The spores that survived the treatment were detected by a colony counting method. The growth activities were measured using a microbial calorimetry technique. The temperature and pH of the spore suspension remained unchanged during the treatment. It was found that the growth activity of B. Stearothermophilus was affected by the pulsed electric field. while no remarkable lethal effect was observed in the range of up to 40 kV/cm.