Bioprospecting and plant growth-promoting bacteria tolerant to salinity associated with Atriplex nummularia L. in saline soils

This study aimed to bioprospect and select halotolerantes bacteria and promoting plant growth associated with the plant Atriplex nummularia L. in saline soils. For bioprospecting of bacteria, samples were collected in five niches and two field experiments located in Serra Talhada and Ibimirim, Pernambuco, Brazil. After collecting the material it was performed the isolation and selection of bacteria based on plant growth promotion mechanisms. 107 bacterial salt tolerant isolates were obtained in which the population density of bacteria was higher in the rhizosphere (107 CFU g-1 soil), the cultivated soil (106 CFU g-1 soil) and uncultivated soil (105 CFU g-1 soil). For the solubilization rate of inorganic phosphate was obtained 65 and 25% positives isolated in 0 to 5% NaCl concentration, respectively. For the characteristics of biological fixation nitrogen, indole acetic acid production, exopolysaccharides and quorum sensing molecule, reached up to 87 percent; 100; 83.33 and 96.66% of the bacteria, respectively. Therefore, the bacterial isolates UAGAt 89 and UAGAt 101 expressed greater tolerance to salinity when analyzed in relation to the characteristics that promote plant growth, making it promising for future studies in order to contribute to the development of Atriplex plants and rehabilitation of soil affected by salts.