Bacteria take plants to biofuel in one step

A lone bacterium, genetically tweaked, can demolish switchgrass and ferment the sugary rubble to ethanol in one fell swoop. The microbe’s one-step conversion of the crop eliminates the need for expensive plant-digesting treatments, offering the potential for cheaper biofuels.

Plucked from hot springs, the bacterium Caldicellulosiruptor bescii grows around 80° Celsius, and naturally wrecks tough, complex plant molecules such as cellulose. Breaking down such roughage into fermentable sugars is one of the trickiest feats for converting plants to ethanol fuel, says geneticist Janet Westpheling of the University of Georgia in Athens. Standard methods require extra steps or costly combinations of enzymes.

For years, researchers have sought a single-step solution, often engineering common microbes that naturally produce ethanol from sugar to become plant destroyers. Westpheling and colleagues tried the reverse: transforming an unusual plant-annihilating