Scientists from Washington State University transferred nitrogen-fixing gene cluster into non-fixing bacteria

Washington State University researchers have transferred a complete cluster of nitrogen-fixing genes from rhizobia into bacteria that could not previously fix atmospheric nitrogen. This marks a significant step toward reducing agriculture’s dependence on synthetic nitrogen fertilizers.

Published in May 2026, the study focused on the “symbiosis island,” a large gene cluster that allows rhizobia to convert atmospheric nitrogen into plant nutrients and form symbiotic relationships with plant roots. The team used a new genetic transfer system to significantly improve the efficiency of moving this complex gene cluster between bacterial species, addressing a longstanding challenge in engineering nitrogen-fixing microbes.

After introducing the symbiosis island into non-fixing bacteria, the researchers conducted millions of bacterial-plant pairings. Many engineered strains formed successful interactions with host plants, with most relationships proving beneficial or neutral rather than harmful. These results challenge the assumption that new microbial symbioses typically start as parasitic before becoming mutually beneficial.

The study also found that bacteria more closely related to naturally nitrogen-fixing rhizobia were more likely to gain functional symbiotic abilities. Led by Stephanie Porter, associate professor of biological sciences at Washington State University, the research demonstrates the potential to expand biological nitrogen fixation beyond legumes using engineered microbial communities.

Despite this progress, practical applications are still years away. Achieving nitrogen fixation in major cereal crops like wheat, corn, and rice will require both engineered bacteria and crop varieties with the necessary molecular receptors to support them. Nevertheless, this research is an important step toward biological alternatives to synthetic nitrogen fertilizers, which are a major agricultural cost and a significant source of greenhouse gas emissions.

Source: Phys.org