Influence of a mono-frequency sound on bacteria can be a function of the sound-level

Chromobacterium violaceum was subjected to sonic stimulation with 300 Hz sound, at five different levels of loudness in the range of 70 - 89.5 dB. Sonic stimulation was found to affect bacterial growth and quorum sensing regulated pigment (violacein) production significantly. Magnitude of this effect was found to be dependent on sound-level. The minimum critical difference required to cause any statistically significant change in bacterial response with respect to sound-level was found to be 13 dB. Growth of C. violaceum was affected more at lower sound intensity, whereas pigment production was affected more at higher sound intensity. Additional experiments with C. violaceum and Serratia mar