Sprintails compared to a penny.
Springtails on a human's fingers.
Posted on 04/07/2020 8:30:02 AM PDT by rightwingcrazy
New research from an international team of scientists is suggesting that instantly recognizable earthy smell after rain is released by bacteria trying to attract a particular arthropod as a way to spread its spores. The smell is a 500-million-year-old example of chemical communication, evolved to help a particular type of bacteria spread.
Scientists have long been fascinated by the unique odor that appears when it rains. The scent is particularly prominent when the first rains of a season hit dry soil. Two Australian researchers named the odor petrichor, after an influential study in the 1960s suggested a particular oil is produced by certain plants during dry periods, and then released into the air when it rains.
One major component of petrichor is an organic compound called geosmin. Scientists have known for some time that a common genus of bacteria, known as Streptomyces, produce geosmin. Virtually all species of Streptomyces release geosmin when they die, but until now it has been unclear exactly why the bacteria generates this distinctive aroma.
“The fact that they all make geosmin suggested that it confers a selective advantage on the bacteria, otherwise they wouldn’t do it,” says an author on the new research, Mark Buttner. “So, we suspected they were signaling to something and the most obvious thing would be some animal or insect that might help distribute the Streptomyces spores.”
Across a number of lab and field experiments the researchers discovered geosmin specifically attracts a type of tiny arthropod called a springtail. Studying the antennae of the springtails the researchers discovered the organisms can directly sense geosmin. The researchers suggest both organisms evolved together, the Streptomyces serving as food for the springtails, while the springtails subsequently spread bacterial spores helping seed new Streptomyces colonies.
“There is mutual benefit,” explains Buttner. “The springtails eat the Streptomyces, so the geosmin is attracting them to a valuable food source. And, the springtails distribute the spores, both stuck on their bodies and in their faeces, which are full of viable spores, so the Streptomyces get dispersed. This is analogous to birds eating the fruits of plants. They get food but they also distribute the seeds, which benefits the plants.”
This symbiotic relationship is key to the survival of Streptomyces, as the bacteria is known to produce certain antibiotic compounds that make it toxic to other organisms such as fruit flies or nematodes. Springtails, on the other hand, generate a number of novel enzymes that can detoxify the antibiotics produced by Streptomyces.
This compelling novel discovery suggests a major element to that iconic wet earth scent is underpinned by a nearly 500-million-year-old relationship between bacteria and arthropods, mediated by an extraordinarily specific mode of chemical communication.
“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,” says Buttner. “So, these small primitive animals have become important in completing the lifecycle of the Streptomyces, one of the most important sources of antibiotics known to science.”
The new study was published in the journal Nature Microbiology.
Source: John Innes Centre
Ping to one of my favorite smells.
“The springtails eat the Streptomyces, so the geosmin is attracting them to a valuable food source. And, the springtails distribute the spores, both stuck on their bodies and in their faeces, which are full of viable spores, so the Streptomyces get dispersed. This is analogous to birds eating the fruits of plants. They get food but they also distribute the seeds, which benefits the plants.”
Well, duh!
I think I preferred not knowing.
On a tangential note - I’ve always felt the air in our area smells so clean after a snowfall.
Someone told me its because the snowflake crystals, in typical crystal behavior, form around particles, and therefore, the snow are forming around dust/dirt/pollutants in the air, and pulling them down to the ground.
True or false?
Nothing better than the smell of sage after a rainstorm in the desert.
“True or false?”
Seems plausible, at least.
Neat little story.
And now I know what scientists were doing while the rest of the world was hoarding toilet paper.
Sprintails compared to a penny.
Springtails on a human's fingers.
Yeah, that’s it. That’s the only reason.
That was my next question. Now we need a study as to why this smell is so pleasing to humans!
How does the smell compare after rain out in the middle of the ocean versus on land?
We are very ignorant of *many* of the mysteries of life.
For example, we now know that
1) The deep ground and rock structure of the earth is FILLED with microbes (they don’t require oxygen) that EAT rock, and other elements. There is probably more living organisms inside the earth than on it.
2) There is more water INSIDE the deep earth than in all the oceans, combined. This was discovered in the last 10 years. In fact, the prevailing theory now is that the oceans were formed from the water that had been inside the earth previously.
I wish I had the grant money to discover the answer to that question.
Its the bladder odor of a deceased dinosaur.
All water is recycled.
Blame Trilobites!
We all have our own truths. ;<)
Thanks rightwingcrazy. I think I graduated with Art, and the Thropod siblings were about a year apart.
I love that smell, too. Now that it’s identified, wouldn’t it be great to make an air freshener with that scent?
Many people claim this smell is ozone from lightning in the atmosphere. I’ve heard this repeated as fact many times over the years.
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