"The bug pulls nitrogen from the air and uses the bioplastic, which is basically stored hydrogen, to drive the fixation cycle to make ammonia for fertilizing crops," Nocera explained.
Harvard researchers have designed an artificial leaf that synthesizes fertilizer. The 'bionic leaf' turns bacteria, sunlight, water and air into nitrogen fertilizer.
The invention could help boost agricultural yields in the developing world.
"When you have a large centralized process and a massive infrastructure, you can easily make and deliver fertilizer," researcher Daniel Nocera said in a news release. "But if I said that now you've got to do it in a village in India onsite with dirty water -- forget it."
The infrastructure and natural resources needed for fertilizer production are often limited in the developing world.
Nocera invented the first bionic leaf, which split water into hydrogen and oxygen. Nocera and his colleagues infused the technology with bacteria to create a fuel-producing leaf.
"The fuels were just the first step," Nocera said. "Getting to that point showed that you can have a renewable chemical synthesis platform. Now we are demonstrating the generality of it by having another type of bacteria take nitrogen out of the atmosphere to make fertilizer."
Researchers added a second bacteria, Xanthobacter, to the system. The microbes turn the leaf's hydrogen and CO2 into a bioplastic that the leaf can use as fuel, creating an entirely self-contained system.
"I can then put the bug in the soil because it has already used the sunlight to make the bioplastic," Nocera said. "Then the bug pulls nitrogen from the air and uses the bioplastic, which is basically stored hydrogen, to drive the fixation cycle to make ammonia for fertilizing crops."
Researchers successfully boosted the biomass of radish plants using the bionic leaf fertilizer.
Nocera and his colleagues presented their breakthrough to attendees at this week's American Chemical Society meeting in San Francisco.