Industrial fertilizers help feed billions of people every year, but they remain beyond the reach of many of the world’s poorest farmers. Now, researchers have engineered microbes that, when added to soil, make fertilizer on demand, producing plants that grow 1.5 times larger than crops not exposed to the bugs or other synthetic fertilizers.
The advance, reported here this week at a meeting of the American Chemical Society, could help farmers in the poorest parts of the world increase their crop yields and combat chronic malnutrition. A key component of fertilizer is nitrogen, an element essential for building everything from DNA to proteins.
Nitrogen is all around us, comprising 80% of the air we breathe. But that nitrogen is inert, bound up in molecules that plants and people can’t access. Some microbes have evolved proteins called nitrogenases that can split apart nitrogen molecules in the air and weld that nitrogen to hydrogen to make ammonia and other compounds that plants can absorb to get their nitrogen.
The industrial process for making fertilizer, invented more than a century ago by a pair of German chemists—Fritz Haber and Carl Bosch—carries out that same molecular knitting.
But the Haber-Bosch process, as it’s now known, necessitates high pressures and temperatures to work. It also requires a source of molecular hydrogen (H2)—typically methane—which is the chief component of natural gas. Methane itself isn’t terribly expensive. But the need to build massive chemical plants to convert methane and nitrogen into ammonia, as well as the massive infrastructure needed to distribute it, prevents many poor countries from easy access to fertilizer.
Des microorganismes génétiquement modifiés pour fournir des nutriments aux plantes bonne lecture (PAM)