Neil Renninger, 33

As a former member of the infamous MIT blackjack team, Neil Renninger knows what it means to make big, calculated risks and see them pay off. Three years ago, he took just such a risk, ­cofounding synthetic­-biology startup ­Amyris while a postdoc at the University of California, Berkeley. The company's new approach to biofuels is now generating serious buzz among investors and interest from cor­porations such as ­Virgin, which recently opened a fuel division.

Amyris started by commercializing a microbial approach to producing a precursor of ­artemisinin, a potent malaria drug (see "10 Emerging Technologies: Bacterial Factories," May 2005). Artemisinin is currently derived from sweet wormwood, but Renninger outlined a way that it could be made more cheaply in bacteria--­helping land a share of a $42 million grant from the Gates Foundation. He is also playing a key role in Amyris's biofuels venture. He began by identifying molecules that would work well as fuels and were compatible with existing engines and delivery infrastructures; then he found a way to combine biological and chemical processes to manufacture them. So far, ­Amyris has created microbes that can produce candidate replacements for biodiesel, jet fuel, and gasoline. "Now we need to tinker with the bug to squeeze out the last bit of metabolic flux that turns something from interesting to cheap enough to burn," he says.

--Emily Singer