Screening of plant growth-promoting traits in arsenic-resistant bacteria isolated from the rhizosphere of soybean plants from Argentinean agricultural soil

ANA LAURA WEVAR OLLER, MELINA A. TALANO, ELIZABETH AGOSTINI

PLANT AND SOIL

SPRINGER

Lugar: Berlin; Año: 2013 vol. 369 p. 93 - 102

0032-079X

Aims The purpose of this study was to investigate plantgrowth promoting traits in native and arsenic (As) highly-resistant bacterial strains isolated from the rhizosphere of soybean (Glycine max) plants grown in an Argentinean agricultural field. Methods Determination of MICs (Minimum inhibitory concentration) was carried out on solid media supplemented with arsenite (As 3+) or arsenate (As 5+). Morphological, cultural, physiological, biochemical and molecular characterization, and in vitro determination of plant growth promoting (PGP) properties of As resistant isolates were carried out. Arsenic in soil samples was determined by ICP-OES while residual arsenic on post-removal culture medium and accumulation in cells were estimated by GF-AAS after wet acid digestion. Results Isolated strains included γ-proteobacteria such as Enterobacter sp. and Pseudomonas sp., and actinobacteria as Rhodococcus sp. All bacterial strains grew in presence of very high arsenite -over 24mMand arsenate ?over 400mM- concentrations. Pseudomonas sp. strains presented simultaneously several in vitro PGP traits, although Rhodococcus erythropolis AW3 did not display PGP traits. However, R. erythropolis AW3 was the most As resistant strain and removed and accumulated the greatest amounts of the metalloid. Conclusion The presence of As resistant and plantgrowth promoting bacterial strains in the rhizosphere of Glycine max, in arsenic containing agricultural soil, suggest that they could potentially play an important role in plant-growth promotion in stressed conditions. These strains were able to remove and accumulate As from liquid media, thus they could be beneficial for sustainable crop production.