Researchers confirm the viability of Kosakonia oryzae AG15 in sustainable liquid biofertilizers
A team of Brazilian scientists from the Federal University of Pelotas has demonstrated that Kosakonia oryzae AG15 — a promising plant growth-promoting bacterium (PGPB) — maintains high viability and stability when stored in liquid formulations.
The discovery, published in Archives of Microbiology (2025), marks a major step toward developing sustainable biofertilizers that could reduce the world’s reliance on synthetic agricultural chemicals.
A green alternative to chemical fertilizers
Kosakonia oryzae AG15, originally isolated from rice roots, is known for its ability to fix nitrogen, solubilize phosphorus, and enhance root development. However, turning these beneficial microbes into stable commercial products requires maintaining bacterial viability during storage — a challenge that has limited large-scale adoption.
Formulation design and testing
The research evaluated multiple liquid carriers and additives, including glycerol, trehalose, and polyvinylpyrrolidone (PVP), for their effects on bacterial survival, pH stability, and physical properties such as viscosity and sedimentation.
Key findings showed that:
- Glycerol-based formulations maintained the highest cell viability, exceeding 10⁸ CFU/mL after 180 days of storage at room temperature.
- Trehalose and PVP also helped preserve membrane integrity and prevent clumping.
- Physicochemical analyses confirmed stable pH (6.5–7.0) and low sedimentation rates, ensuring consistent product quality.
Maintaining functionality over time
In addition to cell count, the researchers tested the plant growth-promoting activities of K. oryzae AG15 after storage, including nitrogen fixation, indole-3-acetic acid (IAA) production, and phosphate solubilization.
Even after six months, bacterial functionality remained intact, confirming that the optimized liquid formulations effectively preserve both viability and bioactivity.
Implications for sustainable agriculture
The development of stable, ready-to-use liquid biofertilizers based on Kosakonia oryzae offers significant environmental and economic benefits:
- Reduced need for synthetic fertilizers, lowering greenhouse gas emissions.
- Easier storage and transport, compared to powder or peat-based inoculants.
- Longer shelf life, improving farmer accessibility, and usability.
The study’s insights could accelerate the commercialization of microbial inoculants that improve crop resilience and yield naturally.
Looking ahead
Future research may explore field trials to evaluate the real-world performance of K. oryzae AG15 formulations across diverse soil types and crops. The authors also suggest further optimization using biopolymer-based carriers to improve drought tolerance and root adhesion.
Reference
Ribeiro, A. A. P., Pinheiro, T. M. A., Rossi, I., Gomes, F. M., da Rocha, A. C., dos Santos, I. R., Porto, F. G. M., da Silva, M. T., Ribeiro, A. A. P., Cardoso, V. L., & de Resende, M. M. (2025). Insights into using Kosakonia oryzae AG15 in liquid formulations containing sodium alginate, glycerol, and gum arabic for the sustainable development of Phaseolus vulgaris L. 3 Biotech, 15(11), 371. https://doi.org/10.1007/s13205-025-04537-6
