Soil bacteria produce an earthy-smelling compound
EMBL-EBI
The institute identifies geosmin as a compound produced by Streptomyces soil bacteria and explains that it contributes to petrichor.
Based on: EMBL-EBI
Verdict
True
Verification confidenceHigh
Explanation
Yes. Part of the familiar earthy smell after rain comes from geosmin, a compound produced by soil bacteria. It contributes to the scent known as petrichor.
EMBL-EBI identifies Streptomyces bacteria as a source of geosmin. The American Chemical Society also explains its contribution to rain-associated smells. Separately, MIT experiments showed that drops hitting porous surfaces can release tiny airborne droplets, offering a mechanism that may carry scent compounds from soil into the air.
Bacteria are only part of the explanation. Compounds from plants also contribute to petrichor. The scent is therefore a mixture associated with rain interacting with its surroundings, rather than a single substance produced by the rain itself.
Key takeaway
The earthy smell after rain has biological ingredients: bacterial geosmin and plant compounds both contribute.
Evidence
Supports the claim
Rain-associated scents have bacterial and plant sources
American Chemical Society
The educational infographic identifies bacterial geosmin as a contributor to the smell associated with rain, alongside compounds originating from plants.
Based on: American Chemical Society
Raindrop impacts can release airborne droplets
Massachusetts Institute of Technology
Experiments documented tiny bubbles bursting out of drops striking porous surfaces. The researchers proposed this aerosol-generating process as a mechanism that may disperse scent compounds from soil.
Based on: Massachusetts Institute of Technology
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