Engineered azotobacter biofertilizer for ammonia excretion and phosphate solubilization
Strains of soil bacteria engineered to excrete ammonia and mobilize phosphorus, reducing chemical fertilizer inputs in agriculture. Early-stage research demonstrates improved phosphate solubilization and plant growth promotion in crops.
Overview
This project focuses on engineering ubiquitous soil microorganisms of the genus Azotobacter to serve as dual-function biofertilizers. By modifying these bacteria to excrete ammonia and solubilize mineral phosphates, the technology aims to reduce reliance on synthetic chemical fertilizers while maintaining or improving crop productivity. The approach targets two of the most critical nutrients for plant growth—nitrogen and phosphorus—through a single microbial platform, offering potential economic and ecological benefits for sustainable agriculture.
Technical specifications
- Nitrogen delivery: Gene-edited Azotobacter strains are designed to produce and excrete ammonia constitutively, transferring it to crop plants without requiring nitrogen fixation at the time of plant demand.
- Phosphate mobilization: The mineral phosphate solubilization (MPS) pathway is engineered by manipulating the expression of quinoprotein glucose dehydrogenase (GDH) genes, which catalyze the oxidation of glucose to gluconic acid, releasing bound soil phosphates.
- Validated performance: Transgenic Azotobacter strains expressing E. coli GDH under Azotobacter-specific promoters demonstrated a 60% improvement in mineral phosphate solubilization and a 50% increase in plant growth-promoting activity in sorghum seedlings, with only a marginal 6% reduction in nitrogen fixation ability.
- Non-transgenic development path: Future work targets generating non-transgenic strains with equivalent phenotypes by engineering strong endogenous promoters to upregulate GDH and PQQ biosynthesis pathway genes natively in Azotobacter vinelandii.
- Assessment methods: Gluconic acid production monitored by HPLC; MPS phenotype evaluated by plate screening and broth culture methods; plant growth-promoting activity estimated through crop inoculation trials.
Technology readiness level
The technology is at an early-to-mid stage of development. Proof-of-concept has been established using transgenic Azotobacter vinelandii strains, demonstrating measurable improvements in phosphate solubilization and plant growth promotion. The current priority is transitioning from transgenic to non-transgenic strains to improve commercial viability and address regulatory considerations associated with genetically modified organisms. Additional validation through crop inoculation trials and pathway optimization is ongoing.
About Washington State University
Washington State University is a comprehensive public land‑grant research university serving the state through a multi‑campus system anchored in Pullman. Industry engagement runs through a research and technology park in Pullman, a health sciences campus in Spokane integrated with regional hospitals, and a statewide extension network linking faculty with companies and communities. The Tri‑Cities campus sits minutes from a U.S. Department of Energy national lab, enabling collaborations, shared facilities access, and talent pipelines for regulated sectors. Research is supported by competitive federal funding from agencies such as NSF, NIH, USDA, DOE, and DoD. A dedicated technology transfer office manages IP, licensing, and startup support, complemented by incubator and pilot‑scale resources.
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