Abstract
Destruction of living organisms by supersonic waves has recently been observed. 1 The mechanism of the destruction is, however, unknown. The present communication extends the observation to a number of pathogenic and nonpathogenic bacteria and the results seem to indicate that the destruction is due to the dissolution of the bacterial cells.
The oscillating circuit was similar to that described by Wu and Liu, 2 and the quartz was adjusted to vibrate at the rate of 1.5 × 106 times per second. Bacterial suspensions to be exposed were placed in a thin test tube, 15 mm. in diameter. Inside the test tube was placed a glass cooling coil through which cold water circulated. The temperature of the bacterial suspension was never over 20° C. The possibility of destruction by heat was therefore eliminated.
Saline suspensions of the following 10 strains of bacteria were used: Bacillus subtilis, Bacillus anthracis, Bacillus proteus X 19, Bacillus coli communis, Bacillus typhosus, Bacillus dysenteriae Shiga, Staphylococcus aureus, Micrococcus catarrhalis, Bacillus influenzae, and Streptococcus hemolyticus. The number of surviving bacteria per cc. before and after exposure was determined by counting the colonies in poured plates. In the case of Bacillus influenzae streak plating was used. Control experiments with bacterial suspension standing at room temperature without exposure showed no significant change in the number of surviving bacteria. Results are shown in Fig. 1.
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