Frequency-Dependent Response of Chromobacterium violaceum to Sonic Stimulation and Altered Gene Expression Associated with Enhanced Violacein Production at 300 Hz

In this study, Chromobacterium violaceum was subjected to sonic (100–2000 Hz) stimulation. Sound waves of 300 Hz frequency promoted bulk production of the quorum-regulated pigment, violacein. Whole transcriptome analysis indicated that a total of 342 genes (i.e. 4.63% of the whole genome) were significantly upregulated 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 pentose phosphate pathway, resulting in an increased availability of erythrose-4-phosphate to be used in the synthesis of tryptophan – the precursor of violacein synthesis. This study is a good demonstration of the ability of sound waves to alter bacterial metabolism.