Soil gets its smell from bacteria trying to attract invertebrates (NewScientistic)
Soil gets its characteristic earthy smell from certain chemicals produced primarily by soil-dwelling bacteria called Streptomyces. But until now, we didn’t know why these bacteria produce these odours and what role they play in the soil ecosystem. To find out more, Paul Becher at the Swedish University of Agricultural Sciences in Alnarp and his colleagues set up field traps in woodland containing colonies of Streptomyces.
They thought that the smell may act as a signal to other organisms that they are poisonous, because some bacteria like Streptomyces can be toxic. Instead, the smell – which comes from gases released by Streptomyces, including geosmin and 2-methylisoborneol (2-MIB) – seems to attract invertebrates that help the bacteria disperse their spores. Becher and his team found that springtails – tiny cousins of insects – that feed on Streptomyces were drawn to the traps containing the bacterial colonies, but weren’t drawn to control traps that didn’t contain Streptomyces. By comparison, insects and arachnids weren’t attracted to the traps containing Streptomyces.