The smell of spring really IS in the air: Scientists reveal why the chemical behind the distinctive earthy scent of the season is produced for the first time
- A bacteria named streptomyces produces the chemical compound geosmin
- This chemical has the distinctive odour we associate with springtime and storms
- Humans have a strong ability to detect this odour and can smell it over others
- It is generated by streptomyces in a bid to attract a worm that spreads its spores
The purpose of a chemical that gives spring its unmistakable earthy odour has been revealed by scientists for the first time – and it’s all down to reproduction.
Geosmin is the chemical that produces the scent of spring and is made by a bacteria called streptomyces in the process of attracting a tiny insect called a springtail.
Scientists from the John Innes Centre in Norwich discovered the link between streptomyces and springtails through a series of experiments.
The team, which included researchers from Sweden, laid traps for the tiny insects using the bacteria as bait and found the springtails were drawn to the streptomyces.
Geosmin is the chemical that produces the scent of spring and is made by a bacteria called streptomyces in the process of attracting a tiny insect called a springtail (pictured)
They discovered that the bacteria produces the earthy smelling geosmin in a large part to draw in the worms which feed on the streptomyces.
Springtails eat the bacteria and in return are completely covered in its spores – which they gradually drop off as they move through the soil – helping it reproduce.
According to the Swedish and British researchers behind the study – streptomyces produce a range of organic compounds including powerful antiobiotics.
Lead author Mark Buttner, from the John Innes Centre, wanted to discover what it was that caused the streptomyces to produce the distinctive smelling compound.
The symbiotic relationship between the two species dates back more than 450 million years and has been described as a ‘seasonal dance’.
‘This is analogous to birds eating the fruits of plants,’ said Buttner, adding that ‘they get food but they also distribute the seeds, which benefits the plants.’.
The Swedish researchers placed the insects in y-shaped tubes – some containing the bacteria and others with control substances.
They also placed electrodes in their antennae to examine their responses to different types of molecules.
In both cases they found the insects were powerfully attracted to the smell of the geosmin produced by streptomyces.
The bacteria produces powerful antibiotics that help humans fight off infects but that also routinely kill off fruit flies and nematodes.
The purpose of a chemical that gives spring its unmistakable earthy odour has been revealed by scientists for the first time – and it’s all down to reproduction
However, further highlighting the symbiotic relationship, springtails have developed enzymes that detoxify any streptomyces antibiotics.
‘There is mutual benefit. The springtails eat the streptomyces, so the geosmin is attracting them to a valuable food source,’ said Buttner.
‘The springtails distribute the spores, both stuck on their bodies and in their faeces.
‘We used to believe streptomyces spores were distributed by wind and water but there is little room for wind or water to do anything in the small air compartments in the soil.
‘So these small primitive animals have become important in completing the life cycle of the streptomyces, one of the most important sources of antibiotics known to science.’
The findings have been published in the journal Nature Microbiology.