D: How was your weekend, Yaël?

Y: Terrific. If there's one thing I love, it's digging in the garden. I even love the smell of      freshly-turned dirt. It smells so rich, so life-giving, so . . .

D: So much like bacteria?

Y: Well...I wasn't going to say that.

D: But it's what you meant. A lot of people love that fresh-dirt smell. The surprising      thing, though, is that it isn't coming from the dirt itself. Microbiologists have traced the      pleasant odor to an organic chemical called "geosmin."

Y: No way!

D: Way.

Y: But how does geosmin get into dirt?

D: That's where the bacteria come in. A microbial geneticist named Keith Chater at the      John Innes Center in England has traced geosmin down to a common bacterium      called Streptomyces coelicolor. He even found out exactly which gene in the little      critters causes them to produce geosmin.

Y: No way. A bacterium is producing the chemical that smells so good?

D: Way.

Y: But why do they do it?

D: Maybe exactly because it smells good! Interestingly enough, there are unconfirmed      reports that animals are attracted to fresh dirt in the desert, and go there looking for      water. As they nose around the dirt, they pick up plenty of S. coelicolor, which then      hitch a ride from one oasis to the next.

Y: Hmmm...like bees spreading pollen.

D: If it's true, then the bacteria in general may create the odor in order to attract animals.      The animals find water, the bacteria are spread, and everyone is happy.

Y: Especially gardeners like me.  

To hear this program click here

A Moment of Science®