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

Abstract

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 marcescens indicated that even a silent speaker emitting no sound can alter bacterial growth and/or pigment production upto a minor extent. Size of the test tube in which bacteria are exposed to sonic stimulation, was not found to affect the results much.

Sonic stimulation, and low power microwave radiation can modulate bacterial virulence towardsCaenorhabditis elegans

“…Liu et al (2016) indicated the possibility of increased release of chemical mediators of QS in sound-exposed endospores. We have also shown altered production of QS-regulated pigments in sound-exposed bacterial cultures Kothari et al, 2018). QS being an important regulator of virulence (Natrah et al ., 2011), any chemical or physical agents capable of modulating QS can be expected to modulate bacterial virulence too.…”

“…Previously we have reported results of our in vitro experiments describing (a) effect of low power MW on microbial growth/metabolism , protein synthesis , enzyme activity (Dholiya et al, 2012), exopolysaccharide production , toxin production (Ramanuj et al, 2015), quorum-sensing (QS) regulated pigment production (Chaudhari et al, 2014), etc. ; effect of sonic stimulation on microbial growth (Sarvaiya and Kothari, 2015;Shah et al, 2016), antibiotic susceptibility (Sarvaiya and Kothari, 2017), and QS-regulated pigment production Kothari et al, 2018). Mutagenic effect of MW has also been previously described by us (Gosai et al, 2013;Kothari et al, 2014).…”

Effects of sound elements on growth, viability and protein production yield in Escherichia coli

“…Considering that IMT had no significant effect regarding biomass concentration, this data suggests that intermittence influences the enhancement of protein production yield in each cell and not because of biomass increment. Although most studies addressing the effect of sound over biomass have used continuous signals, in the present research work, the establishment of the effect of intermittence was considered important. Intermittence parameters were either selected as continuous signal or an intermittent cycle of 20 min sound plus 20 min silence; this value was assigned in relation to E. coli duplication time under typical growth conditions …”

“…7 Furthermore, it has been reported that sound can also upregulate the activity of kinases, disulfide oxidases, chaperones, signal transporters, and genes involved in RNA production in bacteria. 26 Considering that their treatments used sound beeps instead of continuous signals, it is likely that those reported effects are due to intermittence.…”

“…Even when the effects are most noticeable during exponential growth, it cannot be concluded these effects are exclusive to this phase. For instance, studies have found quorum sensing molecules have increased in production during musical treatments, 12,25,26 and these secondary metabolites are expressed during stationary phase.…”