Effect of inoculation with a strain of Pseudomonas fragi in the growth and phosphorous content of strawberry plants

Laura Martín¹, Alvaro Peix², Pedro F. Mateos¹, Eutoquio Martínez-Molina¹, Claudino Rodríguez-Barrueco² and Encarna Velázquez¹

¹Departamento de Microbiología y Genética, Facultad de Farmacia, Edificio Departamental, Universidad de Salamanca, Salamanca 37007, SPAIN.

²Departamento de Producción Vegetal. IRNA. CSIC. Salamanca, SPAIN

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Within genus Pseudomonas, several species are able to solubilize phosphate in plates and some of these species are able to movilize phosphorous to plants. In this work we isolated a strain, SAPA2, from rhizospheric soil of barley growing in a soil from Northern Spain. This strain was able to solubilize phosphates in plates forming great halos of solubilization in 24h. Moreover, this strain retains its ability to solubilize phosphate after five culture passes. The 16S rRNA sequence of this strain showed a similarity of 99,9% with that of Pseudomonas fragi . The inoculation of strawberry plants with this strain was carried out in growth chamber applying 10ml of a suspension containing 10⁸ UFC/ml to each plant. According to the results obtained, the plants inoculated with this strain growing in a soil amended with insoluble phosphate have a phosphorous content significantly higher than uninoculated plants growing in soil with or without insoluble phosphates. Therefore, the fertilization of soil with phosphate solubilizing microorganisms may promote phosphorous mobilization to plants. Our results show that the inoculation of plants with suitable phosphate solubilizing bacteria can increase the crop yield and allows a better exploitation of natural soil resources.