PRODUCTION OF SOUND-WAVES BY BACTERIAL-CELLS AND THE RESPONSE OF BACTERIAL-CELLS TO SOUND

Bacterial cells enhance the proliferation of neighboring cells under s tress conditions by emitting a physical signal. Continuous single sine sound waves produced by a speaker at frequencies of 6-10, 18-22, and 28-38 kHz promoted colony formation by Bacillus carboniphilus under no n-permissive stress conditions of high KCl concentration and high temp erature. Furthermore, sound waves emitted from cells of Bacillius subt ilis at frequencies between 8 and 43 kHz with broad peaks at approxima tely 8.5, 19, 29, and 37 kHz were detected using a sensitive microphon e system. The similarity between the frequency of the sound produced b y B. subtilis and the frequencies that induced a response in B. carbon iphilus and the previously observed growth-promoting effect of B. subt ilis cells upon B. carboniphilus through iron barriers, suggest that t he detected sound waves function as a growth-regulatory signal between cells.