Engineering nitrogen-fixing microbiomes with waste-derived carbon sources: toward circular and resilient...

Area of Science:

• Agricultural Science
• Microbiology
• Biotechnology

Background:

• Synthetic fertilizers pose environmental risks and are costly.
• Microbiome engineering offers a sustainable alternative for agriculture.
• Valorizing waste streams like animal waste is crucial for a circular economy.

Purpose of the Study:

• To engineer a self-assembled, nitrogen-fixing microbial community using animal waste by-products.
• To evaluate the efficacy of this microbial community as a biofertilizer for crop production.
• To assess the potential for transforming waste into high-value bioproducts.

Main Methods:

• Soil samples were enriched in bioreactors with air pumping and volatile fatty acids (VFAs) from anaerobic fermentation.
• A nitrogen-fixing microbial community dominated by *Sinirhodobacter*, *Aureimonas*, and *Taibaiella* species was developed.
• The engineered microbiome was inoculated into tomato plants in hydroponic and soil-based systems.

Main Results:

• The engineered microbiome exhibited 2.7 times higher nitrogen fixation capacity compared to the initial microbiome.
• Inorganic nitrogen forms were detected in the supernatant up to 12.7 mg·L^-1.
• Tomato plants inoculated with the biofertilizer showed significantly enhanced growth and yield, comparable to synthetic fertilizers.

Conclusions:

• Microbiome engineering can create effective biofertilizers from waste materials.
• This approach supports a circular economy and offers a sustainable alternative to synthetic fertilizers.
• The simple bioreactor system is suitable for developing countries and aligns with the One Health vision.