Nitrogen-fixing bacteria, those solid citizens of the agricultural world, could one day be used as a cost-effective source of hydrogen for fuel cells. So say scientists from the Agricultural Research Service (ARS) of the United States Department of Agriculture and North Carolina State University. Commonly found in most soils and on plant roots, nitrogen-fixing bacteria serve to convert nitrogen in the atmosphere into a form that plant life can use as part of their growth process. However, only certain strains of these bacteria are capable of producing hydrogen gas as part of their normal functioning. Working collectively, the ARS/North Carolina State team developed a new patented technology that uses a special "selecting agent" to easily identify these critical strains without having to resort to genomic sequencing or use any type of genetic modification. Culling these bacteria that are, in fact, genetically unable to reabsorb the hydrogen they make opens the door to capturing that essential element and using it to power the fuel cells of tomorrow's zero-emission vehicles.