Agroscope, Käsehaus K3 Burgdorf

How Do Sound Waves Affect Plants and Microorganisms?

Plants and microorganisms can perceive and respond to sound waves. In a review of the literature, Agroscope analysed various publications on this topic. The studies show that sound can lead to positive effects on physiology in the form of improved growth, development and disease resistance.

Studies are increasingly showing that sound waves can have a significant influence on the physiology of plants and microorganisms. The positive effects on physiology, which lead to improved growth, development and disease resistance, are well documented by many studies. However, the available findings are only provisional, and insufficient to answer many questions at cellular level. Results are often contradictory, since there are major differences in how an individual species responds to sound, and the reaction is likewise heavily dependent on the ecosystem in which the species is found. There are still large gaps in our understanding of the cellular events triggered in plants and microorganisms by acoustic stimulation, which will only be bridged by further study. The lack of standardisation of treatment conditions, i.e. of acoustic frequencies and intensities, makes comparisons of different studies difficult.

Sound waves have an influence on cheese quality

The effect of ultrasound waves and waves in the audible range on microorganisms, and consequently on cheese quality, has already been addressed in a number of studies. The influence on cheese quality of bacterial cultures attenuated by means of an ultrasound treatment and added to the starter culture has also been described in a number of papers. This approach often produced a higher peptidase activity, a higher concentration of free amino acids and a more intense flavour in the sensory test.

The idea of using music to influence cheese ripening arose in a collaboration between students at the HKB (Bern University of the Arts) and Käsehaus K3 (‘House of Cheese C3 (Cheese, Culture and Cooperage)’) in Burgdorf as part of the ‘HKB Goes Ashore’ initiative. In this trial, which generated significant international attention, sensory differences were noted between the cheeses, with the cheese wheel exposed to hip-hop music receiving the highest rating. This conclusion is provisional, however, and has yet to be confirmed by further in-depth studies.

At the Käsehaus K3 in Burgdorf, cheese wheels are individually blasted with music. With larger wheels, the sound is transmitted through the lid of the cheese. (Photo: Agroscope)

Promising treatment with lower-intensity ultrasound

Cells can sometimes grow better after exposure to low-intensity ultrasound, since the treatment increases the transport of small molecules in solution. A limited amount of sonoporation (the formation of cavities or pores in the cell membrane as a result of being blasted with sound) is reversible and can improve the transport of substrates or reagents across the cell membrane as well as promote the removal of by-products of cellular metabolism, thus improving cell growth. However, higher levels of sonoporation may be irreversible and lead to the leakage of cell contents since they physically disrupt and/or alter the lipid bilayer of the cell membrane, which ultimately leads to cell death.

Agroscope’s study of the literature also reveals a further interesting prospect: sound waves can help plants, plant microbiomes and microorganisms adapt to changing environmental conditions. This is still a new area of botanical and microbiological research and will require a great deal of commitment and effort.

Conclusions

  • Plants and microorganisms are sentient organisms and apparently much more sensitive and receptive to various environmental stimuli than previously realised.
  • The perception of sounds could be an evolutionarily advantageous adaptive trait for plants.
  • A study of the literature conducted by Agroscope shows that the positive effects of sound waves on growth, development and disease resistance are well documented by numerous research findings.
  • Sound waves may possibly affect cheese cultures, and hence cheese quality.
  • Explaining how sound affects biological systems remains a complicated and difficult task.
  • Low-intensity ultrasound treatment is a promising new area of research and application.
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