Inactivation of Mycobacterium paratuberculosis by pulsed electric fields

The influence of treatment temperature and pulsed electric fields (PEF) on the viability of Mycobacterium paratuberculosis cells suspended in 0.1% (wt /vol) peptone water and in sterilized cow's milk was assessed by direct via ble counts and by transmission electron microscopy (TEM). PEF treatment at 50 degreesC (2,500 pulses at 30 kV/cm) reduced the level of viable M. parat uberculosis cells by approximately 5.3 and 5.9 log(10) CFU/ml in 0.1% pepto ne water and in cow's milk, respectively, while PEF treatment of M. paratub erculosis at lower temperatures resulted in less lethality. Heating alone a t 50 degreesC for 25 min or at 72 degreesC for 25 s (extended high-temperat ure, short-time pasteurization) resulted in reductions of M, paratuberculos is of approximately 0.01 and 2.4 log(10) CFU/ml, respectively. TEM studies revealed that exposure to PEF treatment resulted in substantial damage at t he cellular level to M. paratuberculosis.