How Genetically Engineered Microbes Can Improve Crop Growth and Global Food Production

Humans have used biofertilizers, including manure, for thousands of years. Today, agricultural companies are developing microbial fertilizers that use living microorganisms—and, in some cases, genetic engineering—to improve crop nutrition. However, engineering microbes that can reliably provide nitrogen to plants while also surviving and multiplying independently remains a major challenge.

Switch Bioworks, a biotechnology startup, is taking a new approach. Its technology is designed to help microorganisms first colonize plant roots and establish healthy populations before switching into nitrogen-producing mode. “We need to reinvent fertilizer,” says Tim Schnabel, founder and CEO of Switch Bioworks.

Although atmospheric air is nearly 80% nitrogen, plants cannot directly use this abundant supply because nitrogen gas is relatively unreactive. Plants depend on “fixed” nitrogen, which is converted into reactive compounds such as ammonia. In nature, nitrogen-fixing microorganisms perform this conversion. Legumes, including soybeans and peas, have a symbiotic relationship with nitrogen-fixing bacteria that live in nodules on their roots. By contrast, synthetic fertilizers use the Haber-Bosch process, which relies on natural gas to produce ammonia for agricultural use.

Microbial biofertilizers are designed to reduce reliance on synthetic fertilizers by using microorganisms that help plants access or fix nitrogen. One of the biggest challenges is that nitrogen fixation requires substantial energy. When microbes devote too much energy to producing and releasing ammonia, their growth can slow, limiting their ability to colonize plant roots and support crop development.

“You want to see some colonization around the roots,” Schnabel explains. Because it is expensive and logistically difficult to apply enough microorganisms to every plant, farmers need microbial fertilizers whose organisms can grow, divide, and establish a strong population from a relatively small initial dose.

Switch Bioworks believes genetic switches could help solve this problem. These DNA sequences control when specific genes are turned on or off. In the company’s system, a genetic switch activates genes that enable microorganisms to produce ammonia inside their cells and release it into the surrounding environment. Switch Bioworks is evaluating several ways to trigger this response, with one key strategy based on nitrogen levels in the soil. When available nitrogen falls below a certain threshold, the microorganisms would switch on nitrogen production.

“There’s an inherent biological reality that it’s very expensive for microbes to fix nitrogen,” says Dan Blaustein Reit, director of food and agriculture at the Breakthrough Institute. Nitrogen fixation requires significant energy, and microorganisms may prefer to use that energy to produce proteins and support their own survival. A carefully controlled genetic switch could allow microbes to grow and thrive first, then produce nitrogen when crops need additional nutrients.

Switch Bioworks is currently testing its microbial fertilizer technology in six US states. Schnabel estimates that commercialization could take another two to three years. The company’s initial target is corn, the most widely planted crop in the United States, where more than 90 million acres are expected to be planted by 2026.