Isolation and characterization of phosphate solubilizing bacteria from phosphate mines and investigation on their soil phosphate solubilization potential

The aim of this study was to isolate and characterize phosphate-solubilizing bacteria from two phosphate mines and to investigate their soil phosphate solubility ability. Eighty five colonies with different morphologies were isolated and purified using the liquid Sperber culture medium enriched with Yazd’ Esphordi soil phosphate (YESP) and a form of diluents series in the Sparber solid culture medium enriched with YESP. Four out of 85 isolates (Rpy: from Esfordi mine and Tkd/4, Ggd/4 & Rpd/4 from Jiroud mine) with the highest amount of dissolved phosphorus in the Sperber liquid medium enriched with YESP as superior isolates were selected. With using 16S rRNA gene sequencing the isolates Tkd/4, Rpd/4, Rpy and Ggd/4 were recognized very closely (more than 99%) to Curtobacterium flaccumfaciens, Sphingobium yanoikuyae, Bacillus pumilus and Pantoaea aglomerans genera respectively. The multifold release of phosphorus by these isolates compared to the control from three phosphate sources showed that these bacteria can dissolve other phosphate sources.