Effect of a type of Indian classical music (Raag Kirwani) comprised of the sound corresponding to a frequency range of 38-689 Hz, on microbial growth, production of certain important metabolites, and antibiotic susceptibility was investigated. All the bacteria and yeasts used as test organisms were found to reg ister better (3.15-40.37% higher) growth under the influence of music, except Serratia marcescens. Music treatment was also found to affect production of bacterial pigments (prodigiosin and violacein) whose pro duction is normally linked with quorum sensing in the producing bacteria. All the test organisms exhibited an increased antibiotic susceptibility (increase ranging from 3.81-18.69%) under the influence of music. Chromobacterium violaceum and S. marcescens were found to degrade cephazolin at a faster rate when incu bated with music. Membrane permeability of the test organisms seemed to get altered owing to music treat ment. Intracellular concentration of cations (calcium and potassium) and protein content of the music treated cultures was also significantly different than the untreated control. The audible sound in form of music employed in this study was able to affect growth, metabolism, and antibiotic susceptibility of prokaryotic as well as eukaryotic microbes.

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Effect of a type of Indian classical music (Raag Malhar) comprised of the sound corresponding to a frequency range of 41-645 Hz, on microbial growth, production of certain important metabolites and antibiotic susceptibility was investigated. All the bacteria and yeasts used as test organisms were found to register better growth under the influence of music, except Serratia marcescens. Music treatment was also found to promote production of bacterial pigments (prodigiosin and violacein) whose production is normally linked with quorum sensing in the producing bacteria. All the test organisms (except S. marcescens) exhibited an increased antibiotic susceptibility under the influence of music. Chromobacterium violaceum and S. marcescens were found to degrade cefazolin at a faster rate when incubated with music. Membrane permeability of the test organisms seemed to get altered owing to music treatment. Concentration of cations (calcium and potassium) and protein content of the music treated cultures was also significantly different than the untreated control. Alcohol tolerance of Saccharomyces cerevisiae was also notably enhanced under the influence of music.

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.

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