Microorganismos solubilizadores de fosfato en dos regiones agroecológicas de la provincia de Tucumán

Abstract

The urgent need for sustainable and low environmental impact strategies in agriculture requires the development of microbial preparations that improve plant nutrition. Phosphate solubilizing microorganisms are ubiquitous
in soils and could play an important role in supplying phosphorus to plants. Isolation of indigenous micro flora is an important procedure to optimize the biological contribution of phosphorus. The aim of this work was to study the activity of phosphate solubilizing microorganisms in two agro ecological areas of the province of Tucumán. Other objectives were to determine presence, to isolate, to evaluate solubilization efficiency and to characterize the phosphate solubilizing microorganisms. Rhizospheric soil samples of soybean (Glicine max L. Merr.) were collected from two agro ecological areas of Tucumán. Physical and chemical analyses of soil were performed and the presence and counting of phosphate solubilizing microorganisms was conducted by the plate dilution technique in NBRIP medium. Strains that showed solubilization halo were selected and purified on TSA medium. In order to determine the phenotypic diversity, bacteria characterization was done on the basis of morphology, motility, Gram’s reaction, solubilization efficiency, hydrolysis of starch and gelatin, catalase, oxidase, glucose and lactose fermentation, citrate, urease, diffusible pigment production, siderophores and indoles production. The isolates were characterized as Pseudomonas fluorescens, Pseudomonas aeruginosa, Klebsiella spp. and Serratia spp. that could be used as plant growth promoting rhizobacteria.