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

Abstract

ABSTRACT:Chromobacterium violaceum was subjected to sonic (100-2000 Hz) stimulation, and the effect on its cell yield and quorum sensing regulated pigment (violacein) production was investigated. Sound corresponding to the 300 Hz was found to promote (by 1.52 fold) violacein production the most, with only marginal impact on cell yield. Whole transcriptome analysis revealed that a total of 342 genes (i.e. 4.63% of whole genome) were significantly up-regulated in the sonic stimulated culture. Enhanced violacein production in the sound stimulated culture seems to have stemmed from enhanced expression of the genes involved in glucose metabolism through pentose phosphate pathway, resulting in increased availability of erythrose-4-phosphate, to be used for synthesis of tryptophan, the precursor for violacein synthesis. Multiple ribosomal subunit genes, enzyme coding genes, and those associated with secretion/transport were up-regulated owing to sonic stimulation. This study is a good demonstration of the ability of sound waves to alter bacterial metabolism.

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

“…Because this increase is not due to an increase of biomass, intermittence is likely to affect gene expression in ways other than oxidative stress just as found in tobacco plants where sound was able to upregulate specific transcription factors . 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 . 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, and these secondary metabolites are expressed during stationary phase.…”

Convergent gain and loss of genomic islands drive lifestyle changes in plant-associated Pseudomonas

“…The quorum sensing biosensor assay was carried out by restreaking single colonies of wild-type and mutant strains on LB with 1.5% agar next to a streak of Chromobacterium violaceaum CV026, then incubating as previously described 19,20 . For selected strains in the P. brassicacearum clade (as well as the ∆luxILPQ N2C3 mutant), we also performed a quantitative assessment of violacein production as previously described 21 . Briefly, each strain of interest was streaked three times next to a streak of C. violaceum CV026 on LB agar and incubated overnight.…”