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Characterization of Halotolerant Pseudomonas spp. Strains with Phosphate Solubilizing Ability
Jošić, Dragana
Dinić, Zoran
Pivić, Radmila
Iličić, Renata
Latković, Dragana
Abstract: Phosphorus is one of the essential macronutrient required for plant growth. Phosphorus (P) mainly exists in soil in insoluble or very poorly soluble organic and inorganic forms and, therefore, unavailable to plants. P-solubilization property is one of the most important plant growth promoting (PGP) traits of bacteria associated with plant nutrition. High salinity also affects plant growth through osmotic effects, the changes in the physical and chemical properties of soil and toxicity of salt ions. Halotolerant microorganisms are adapted to tolerate high salt concentration and grow in saline environments. PGP halotolerant bacteria are known to improve plant nutrition on saline soil. The aim of this study was to characterize rhizospheric and endophytic halotolerant Pseudomonas spp. strains able to convert insoluble P to an accessible form. Tolerance to salinity stress was tested in Nutrient agar medium supplemented with 1 - 5% NaCl and halotolerant Pseudomonas spp. strains were selected. Phosphate solubilization was analyzed in Pikovskaya’s medium containing insoluble tricalcium phosphate (TCP) as sole source of P. Several strains showed clear zones around the colonies grown on solid Pikovskaya’s medium. Their mineralizing phosphate ability was related to the levels of acid production and decreasing pH values. Biochemical properties of selected strains were observed using API 20NE and API Zym tests. Genetic characterization was performed using BOX-PCR and the nucleotide sequences of the nearly full-length 16S rRNA genes by using fD1/rD1 primer set. Multiple PGP traits of three Pseudomonas spp. strains, especially beneficial phosphate solubilizing ability and tolerance to 3.5% salt concentration, were found very important for offering an alternative of using those strains instead of phosphorus fertilizers.
engleski
2018
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Halotolerant bacteria, Pseudomonas spp., Phosphate solubilization