A new study published in the Journal of Plant Growth Regulation reports the discovery of a highly effective halo-tolerant phosphate-solubilising bacterium, Cronobacter muytjensii, isolated from the coral reef ecosystem of Rameswaram, India. The research demonstrates that this marine-derived strain can significantly enhance soil fertility and support plant growth even under challenging saline conditions.
The bacterium exhibited strong phosphate-solubilising activity, performing optimally at pH 8 and 35 psu salinity, and remained active up to 40 psu and pH 9. Detailed analyses revealed that the strain produces a range of organic acids—including gluconic, oxalic, formic, malonic, keto-gluconic, and citric acids—which play a central role in lowering soil pH and converting insoluble phosphates into plant-available forms.
Beyond phosphorus solubilisation, C. muytjensii demonstrated multiple plant-growth-promoting traits:
- Indole-3-acetic acid (IAA) production
- Nitrogen fixation
- Potassium solubilisation (SI = 3.2)
- Enzyme production, including phosphatase, phytase, urease, cellulase, and catalase
The bacterium also acted as a biocontrol agent, inhibiting several phytopathogenic fungi such as Helminthosporium oryzae, Alternaria spp., Pyricularia oryzae, Xanthomonas oryzae, and Rhizoctonia solani.
In plant growth experiments using rice, tomato, and chilli, seed treatments with C. muytjensii resulted in substantial improvements in shoot length, root length, biomass, and overall plant vigor. Corresponding soil analyses showed reduced pH, increased soluble phosphorus, and a dramatic rise in PSB populations.
The study concludes that C. muytjensii offers a powerful, eco-friendly alternative to chemical fertilizers for phosphate reclamation and plant growth promotion in saline-affected agricultural soils.
Reference
Kailasam, S., Arumugam, S., Masilamani, D. et al. Halo-Tolerant Phosphate-Solubilising Bacterium from Coral Reef: A Potential Bioagent for Phosphate Reclamation and Soil Fertility Enhancement. J Plant Growth Regul (2025). https://doi.org/10.1007/s00344-025-11954-7
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