Abstract
The present study was conducted to isolate phosphate solubilizing bacteria (PSB) from rhizospheric saline soils of coastal Odisha, India and evaluated their phosphate solubilizing ability. Total four PSB were isolated based on the halo zone formation (solubilizing index 2.63-3.14) on PVK agar medium and were characterized based on biochemical and molecular characteristics as Bacillus subtilis (B1), B. megaterium (B2), Sphingomonas paucimobilis (P2) and Kocuria kristinae (P6). The inorganic phosphate released by PSB ranged from 18.532 to 38.250µg/ml with decreasing the pH PVK broth up to 3.9. Acid phosphatase activity for PSB were recorded 84.237-98.658µmol/min. Glucose was found to be the best carbon source for B. subtilis, Sphingomonas paucimobilis and Kocuria kristinae whereas mannitol for B. megaterium. Optimum acid phosphatase activity was observed for all the four PSB isolates in presence of ammonium sulphate as nitrogen source in PVK broth at 30oC and pH 7.0.
Highlights
Introduction95-99% of soil P presents as insoluble form [36] both in organic and inorganic form, which makes it a major growth limiting factor for plant [14]
Solubilizing Index (SI) and Phosphate solubilizing efficiency (PSE) of phosphate solubilizing bacteria (PSB) After seven days of incubation, clear halo zone was observed surrounding the colonies on the PVK agar plates which is measured and the data is given in table 1
The efficacy of acid phosphatase production by Sphingomonas paucimobilis, Kocuria kristinae and Bacillus subtilis was maximum in PVK medium containing glucose mannitol as the sole source of carbon whereas by Bacillus megaterium it was maximum in PVK medium containing mannitol as the sole source of carbon (Fig 3A)
Summary
95-99% of soil P presents as insoluble form [36] both in organic and inorganic form, which makes it a major growth limiting factor for plant [14]. This unavailability of P is due to P-fixation, either it is absorbed by the soil minerals or get precipitated by free Al3+ and Fe3+ in the soil solution [32, 15]. The mechanisms by which plant growth promoting rhizobacteria (PGPR) promote plant growth, include the ability to produce phytohormones, asymbiotic nitrogen fixation against phytopathogenic microorganisms by production of siderophores, the synthesis of antibiotics, enzymes and/or fungicidal compounds and solubilization of mineral phosphates and other nutrients [12].
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
