Bacterial resistance to ultrasonic waves under pressure at nonlethal (manosonication) and lethal (manothermosonication) temperatures

The decimal reduction times of Streptococcus faecium, Listeria monocytogene s, Salmonella enteritidis, and Aeromonas hydrophila corresponding to heat t reatment at 62 degrees C were 7.1, 0.34, 0.024, and 0.0096 min, and those c orresponding to manosonication treatment (40 degrees C, 200 kPa, 117 mu m) were 4.0, 1.5, 0.86, and 0.90 min, respectively, The manosonication decimal reduction times of the four species investigated decreased sixfold when th e amplitude was increased from 62 to 150 mu m and fivefold when the relativ e pressure was raised from 0 to 400 kPa. In L. monocytogenes, S. enteritidi s, and A. hydrophila, the lethal effect of manothermosonication was the res ult of the addition of the lethal effects of heat and manosonication, where as in S. faecium it was a synergistic effect.