Isolation and characterization of phosphate solubilizing bacteria in northwestern Argentina and its effect in promoting growth in maize (Zea mays>/em> L.)

Abstract

Phosphate solubilizer bacteria perform an important role in the phosphorous supply for plants. This factor calls the attention for its use as commercial inoculate or the management of its population to promote a better use
of phosphate present in soil or the one added as fertilizer. The aim of this work was to study the activity of the phosphate solubilizers bacteria isolated from three locations of Northwestern Argentina. Other objectives were to
isolate the ones founded in biggest proportion, to evaluate solubilization efficiency, to characterize them through biochemical and molecular test and evaluate its capacity to promote the growth in corn (Zea mays L.). Rhizospheric
soil samples were taken from three locations in the NWA region and the presence and counting of phosphate solubilizing bacteria was conducted by the plate dilution technique in NBRIP medium. Strains that showed
solubilization halo were selected and purified on TSA medium. Morphology, motility, cellular wall, solubilization efficiency were determined and biochemical tests were made which allows to identify them as Pseudomonas spp., Pseudomonas aurantiaca, Serratia fonticola, Proteus spp., Bacillus subtilis, Bacillus megaterium and Bacillus spp. Amplification and sequencing of the 16S rDNA gene of the ones with higher efficiency of solubilization was
performed. To prove the promoting effect of maize growth under controlled conditions, length and dry weight of stem and root were evaluated. The result showed that the inoculated plants produced increases in the analyzed
parameters in relation to the control, allowing to infer that three bacteria can be used to stimulate plant growth.