What is Nitrogen Fixation?

The biological or synthetic process of converting atmospheric nitrogen gas (N2) into ammonia or other reactive nitrogen compounds that can be assimilated by plants, a critical function for agriculture that synthetic biology aims to engineer into crop-associated microbes.

What category does Nitrogen Fixation belong to?

Nitrogen Fixation is a agriculture concept in synthetic biology and synbio technology.

Nitrogen Fixation — Synthetic Biology Glossary

Nitrogen fixation is one of the most impactful targets for agricultural synthetic biology. Atmospheric nitrogen is abundant but inaccessible to most organisms; only certain bacteria and archaea possess the nitrogenase enzyme complex capable of converting N2 to ammonia. The industrial Haber-Bosch process, which fixes nitrogen using high temperatures and pressures, consumes approximately 1 to 2 percent of global energy production and is a major source of greenhouse gas emissions. Engineering biological nitrogen fixation into cereal crops or their associated microbes could dramatically reduce dependence on synthetic fertilizers, benefiting both economics and the environment.

Several companies are pursuing biological nitrogen fixation for agriculture. Pivot Bio has developed microbial products that colonize crop roots and provide biologically fixed nitrogen directly to corn and other cereal crops. Their product PROVEN uses engineered bacteria with reactivated nitrogen fixation genes, which had been silenced over evolutionary time as plants began receiving synthetic fertilizer. Joyn Bio (a joint venture between Ginkgo Bioworks and Bayer, later wound down) sought to engineer nitrogen-fixing microbes for cereal crops using synthetic biology tools. Roke, founded by researchers from MIT, is working on engineering nitrogen fixation in plant cells themselves.

The fundamental biology of nitrogen fixation presents significant engineering challenges. The nitrogenase enzyme is extremely sensitive to oxygen, requiring elaborate protection mechanisms in aerobic organisms. Transferring the nitrogen fixation (nif) gene cluster, which includes more than a dozen genes, into new host organisms while maintaining proper regulation and oxygen protection is a formidable synthetic biology challenge. Despite these difficulties, progress is being made through approaches including engineering oxygen-tolerant nitrogenase variants, developing synthetic gene circuits that control nif gene expression in response to environmental signals, and optimizing plant-microbe interactions to improve nitrogen delivery efficiency.