Everyone knows that pleasant "earthy" smell of newly ploughed soil and the unpleasant "musty" smell of water, fish, and corked wine. Now, scientists have discovered how geosmin, the chemical responsible for those smells, is formed. David Cane and two of his graduate students at Brown University in Providence recently demonstrated the mechanism by which geosmin is produced, by splitting the enzyme responsible for geosmin synthesis into two halves. They then demonstrated that the first half of the enzyme converts another organic compound called farnesyl diphosphate to an intermediate product and the second half converts this intermediate product to geosmin. This is a surprising finding because researchers so far believed that one half of the enzyme was inactive. Researchers also demonstrated that geosmin is not produced if one half of the enzyme is blocked, proving that both halves of the enzyme are actually active but work in two separate specialized ways to produce geosmin.
BOTTOM LINE: "We now know how this substance, that everyone on earth knows, is produced," said Cane. "Knowing how it is produced has economic implications because we can now devise ways to control the 'musty' smell of water, fish, wine or even the damp smell in moldy buildings."
CAUTIONS: This is the first study to uncover the basic mechanism of geosmin formation and more studies are necessary to understand it in more detail.
WHAT'S NEXT: Cane and colleagues want to find out how the two halves of the enzyme responsible for geosmin synthesis "talk" to each other - how the product produced by one half is sensed and taken up by the other half to complete the process.
WHERE TO FIND IT: Nature Chemical Biology online, Sept. 16
SENA DESAI GOPAL
turn thin air into food
BOTTOM LINE: Scientists can now observe at the cellular level how animals are absorbing and benefiting from nitrogen, a key element for life on earth.
CAUTIONS: The researchers were unable to explain how the shipworms insulate the bacteria from oxygen, which is usually present in an animal's gills and can stall nitrogen fixation.
WHAT'S NEXT: Understanding how animals fix nitrogen might help agricultural engineers improve the process in plants, allowing farms to produce more food while conserving fertilizer, Distel said.
WHERE TO FIND IT: Science, Sept. 14