MAKE clean fuel or feed the world? That鈥檚 the dilemma facing biofuel producers now that the world food crisis is making the turning of food crops into biofuel seem increasingly irresponsible. But maybe there鈥檚 a way out.
One option would be to make fuel from cellulose 鈥� the tough, inedible parts of plants 鈥� but until now the process has proved too costly and laborious. Bacteria are genetically modified to produce cellulases that digest cellulose, turning it into sugars which are then fermented into ethanol fuel.
Now Mariam Sticklen of Michigan State University in East Lansing and colleagues have engineered a fuel plant to make its own cellulases 鈥� a bit like oil that refines itself into petroleum.
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But how do you stop the plant chewing up its own cell walls as it grows? 鈥淭he enzymes are stored in a cellular compartment away from the walls,鈥� Sticklen says. Her team have created a transgenic corn variety, Spartan III, which produces cellulases that only work when the plant is ground up and heated (Nature Reviews Genetics, vol 9, p 433).
Such a gene could wreak havoc if pollen from the corn reached other plants. One solution, Sticklen suggests, might be to insert the cellulase gene into the DNA in chloroplasts 鈥� where photosynthesis takes place 鈥� instead of the plant鈥檚 nuclear DNA. Because pollen does not contain chloroplasts, the gene would be unlikely to spread readily to other plants, she says.
鈥淏ecause pollen does not contain chloroplasts, the gene would be unlikely to spread鈥�
Energy and Fuels 鈥� Learn more about the looming energy crisis in our comprehensive special report.
