Growth and Physiological Characteristics of E. coli in Response to the Exposure of Sound Field

It is undeniable that environmental sonic vibration can affect our emotions and mood, but so far the study of physical stimuli provoked by audible wave on single cells has been rarely concerned. To investigate the response of E. coli to audible wave exposure, the growth status and alterations in antioxidant enzyme activity were studied in liquid culture. The data showed that the growth of E. coli was promoted in the treatments of different frequencies sound wave. The most significant effect on growth promotion appeared when sound wave was maintained at 100 dB and 5000 Hz. Simultaneously, sonic vibration evoked significantly increases the level of total protein content contents. And the changes of activities of Super Oxide Dismutase (SOD) and catalase (CAT) were observed obviously. The results suggested that the growth promotion effect of audible sound may be non-linear and shows obvious frequency and intensity peculiarities. Moreover, the increase in activity of antioxidant enzymes implied that a number of active oxygen species generated in bacterial cell under the exposure of audible sound. We speculate that the audible sound may cause a secondary oxidative stress. Further studies are needed to elucidate the mechanisms of active oxygen species generation induced by audible sound.