Effects of sound exposure on the growth and intracellular macromolecular synthesis ofE. colik-12

Abstract

Microbes, as one of the primary producers of the biosphere, play an important role in ecosystems. Exploring the mechanism of adaptation and resistance of microbial population to various environmental factors has come into focus in the fields of modern microbial ecology and molecular ecology. However, facing the increasingly serious problem of acoustic pollution, very few efforts have been put forth into studying the relation of single cell organisms and sound field exposure. Herein, we studied the biological effects of sound exposure on the growth of E. coli K-12 with different acoustic parameters. The effects of sound exposure on the intracellular macromolecular synthesis and cellular morphology of E. coli K-12 were also analyzed and discussed. Experimental results indicated that E. coli K-12 exposed to sound waves owned a higher biomass and a faster specific growth rate compared to the control group. Also, the average length of E. coli K-12 cells increased more than 27.26%. The maximum biomass and maximum specific growth rate of the stimulation group by 8000 Hz, 80dB sound wave was about 1.7 times and 2.5 times that of the control group, respectively. Moreover, it was observed that E. coli K-12 can respond rapidly to sound stress at both the transcriptional and posttranscriptional levels by promoting the synthesis of intracellular RNA and total protein. Some potential mechanisms may be involved in the responses of bacterial cells to sound stress.

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

“…This biological effect of intermittence can be explained if physical stress mechanoreceptor channels are considered as the mechanism by which E. coli detects sound channels . A continuous complex stimulus may saturate the response of the mechanoreceptor channels making them unresponsive, in a very similar way to the onset of insulin resistance.…”

“…It has already been reported that sound enhances biomass growth in E. coli. [8][9][10]16 However, in previous reports, a clear correlation between individual sound elements and the response (biomass concentration) could not be concluded as the treatments consisted of complex musical compositions or they merely focused on frequency.…”

“…[2] beaker, [3] plastic supporter, [4] speaker, [5] sound generator, [6] flexible tubing, [7] sample receiver, [8] flask swab, [9] lid with two outlets, [10] syringe, [11] 0.45 mm filter, [12] tweezers, [13] cotton. bottle cap [9]; on the second outlet, a syringe [10] with a 0.45 mm filter [11] was attached to generate a pressure difference so that the sample could move from the flask to the beaker. When samples were not being collected, tweezers [12] were used on the flexible tubing to stop the air flow.…”

“…Regardless of the description of sound effects on organisms, the specific process by which it influences different molecular mechanisms is poorly understood. It has been suggested that sound promotes vibration of the cell membrane while increasing selectivity towards certain compounds that stimulate cell growth, but other hypotheses state that sound waves can regulate gene expression by modifying transcription factors or by activating physical stress mechanoreceptor channels . More recently, it has been stated that living organisms respond to a combination of sound patterns which could carry biological information and that cell membranes have the capacity to decode and transmit this information, thus spreading the effect within a certain population …”

Frequency-dependent response ofChromobacterium violaceumto sonic stimulation, and altered gene expression associated with enhanced violacein production at 300 Hz

“…Though the interaction of microbial cells with audible range of sound has not been researched much, there are quite a few reports (Aggio et al, 2012;Cai et al, 2015;Sarvaiya and Kothari, 2015;Gu et al, 2016;Shah et al, 2016) describing microbial growth and metabolism getting affected by sound stimulation. Whether microbes respond to sonic stimulation in a frequency-dependent fashion, is an interesting problem to investigate.…”