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bioRxiv · 10.1101/2025.09.01.673583

Defying Salinity, Drought, and pH Extremes: A Multifunctional Rhizobacterium, Burkholderia gladioli ST3M-39a, Matches Fertilizer Efficacy in Wheat via Phosphate Solubilization

Silwal, S.·Shrestha, A.·Pokharel, S.·Khanal, B. C.·Acharya, R.·Pandey, G. R.
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Abstract

Global phosphorus scarcity and the environmental impacts of chemical fertilizers necessitate sustainable microbial alternatives for agriculture. We characterized Burkholderia gladioli ST3M-39a, a maize rhizosphere isolate, as a multifunctional plant growth-promoting rhizobacterium with exceptional climate resilience. The strain achieved rapid phosphate solubilization (177.96 {+/-} 5.26 {micro}g/mL within 24 h; molybdenum-antimony assay), zinc solubilization, and ammonia production, EPS production, and produced stress-alleviating enzymes (cellulase and protease). Crucially, it maintained robust growth and phosphate-mobilizing capacity under extreme abiotic stresses: pH 4.5-8.5, 7.5% NaCl salinity, and drought-mimicking low water activity (aw 0.950, 32% sorbitol). In wheat trials, ST3M-39a inoculation significantly increased the growth parameters (p < 0.05 vs. those of the uninoculated controls), resulting in 85-92% of the biomass stimulation observed with diammonium phosphate (DAP) fertilizer. This multifunctional stress tolerance, coupled with its near-fertilizer efficacy, positioned ST3M-39a as a transformative bioinoculant for degraded soils. Field validation of its agricultural deployment and ecological impact is now pivotal.

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Silwal, S., Shrestha, A., Pokharel, S., Khanal, B. C., Acharya, R., Pandey, G. R.. 2025-09-03. Defying Salinity, Drought, and pH Extremes: A Multifunctional Rhizobacterium, Burkholderia gladioli ST3M-39a, Matches Fertilizer Efficacy in Wheat via Phosphate Solubilization. https://doi.org/10.1101/2025.09.01.673583

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