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It’s a problem all earthly life forms must solve: where to get nitrogen? From plants to people, the element is a crucial building block of DNA, proteins, and other biomolecules. “Carbon, nitrogen, [and] phosphorus are the big three things that you totally need to put biomass together,” says Connie Lovejoy, a microbial ecologist at Laval University in Quebec.
But only a select group of microbes, known as diazotrophs, can pluck N2 gas from the air or dissolved N2 in water and convert it into ammonium, a process called nitrogen fixation, so that it can then be used to build other biomolecules. Most of the rest of us piggyback on their labor in some way, and, to a smaller extent, on nitrogen-fixing chemical reactions catalyzed by lightning and volcanoes. Nitrogen fixation “is really energy-expensive,” because it necessitates breaking the triple bond between two nitrogen atoms, explains Deborah ...
