MADISON -- As the southern pine beetle moves through the forest boring tunnels inside the bark of trees, it brings with it both a helper and a competitor. The helper is a fungus that the insect plants inside the tunnels as food for its young. But also riding along is a tiny, hitchhiking mite, which likewise carries a fungus for feeding its own larvae.
Now the picture of this peculiar, millennia-old arrangement has grown even more curious. Writing in the Oct. 3 issue of Science, a team of researchers reports that the pine beetle harnesses a second microorganism a bacterium known as an actinomycete to protect its fungus from the mite's competing one. What's more, the bacterium does so by wielding an antibiotic that is brand new to science.
The isolation of the novel antifungal compound dubbed mycangimycin for the specialized compartments, or mycangia, in which the beetles carry both their fungi and bacteria raises the intriguing possibility that other such discoveries could follow.
"There are perhaps 10 million species of insects on the planet," says University of Wisconsin-Madison evolutionary biologist and symbiosis expert, Cameron Currie, who led the study with Harvard University chemist Jon Clardy. "So, if insects associate with actinomycetes like this more generally, then there's potentially a huge number of new places to explore."
The realization couldn't come at a better time. Historically, the greatest source of antibiotics in the world has been the actinomycetes, especially members of the genus Streptomyces. But in recent years, the number of new compounds successfully isolated from these organisms and indeed from all microbes has dwindled, even as resistance to existing antibiotics has spread.
Whether symbiotic associations end up being a treasure trove of new antimicrobials and other useful agents remains to be seen. But it's promising to see insects pairing up with actinomycetes.'/>"/>
|Contact: Jarrod Scott|
University of Wisconsin-Madison