In this study, it was aimed to determine the bacteria species of inorganic phosphate-solubilizing bacteria (IPSB) isolated from sediment samples collected from Lake Van, Turkey. The National Botanical Research Institute's phosphate (NBRIP)-bromophenol blue (BPB) growth medium was used to screen the IPSB. An alkalotolerant isolate was determined in the soluble tricalcium phosphate in the NBRIP-BPB medium. This isolate, called the S1 isolate, had a wide tolerance, ranging from pH 5.0 to 10.0. As a result of the spectrophotometric measurements, it was determined that the S1 isolate dissolved a maximum amount of PO4-3 (109.6 mg/L) at pH 6.0, 30 degrees C, and 120 h. In addition, phenotypic and molecular identification of the S1 isolate that dissolved in the inorganic phosphate was performed. Within the scope of molecular identification, the 16S ribosomal RNA region was amplified by polymerase chain reaction using appropriate universal primers. It was determined that this isolate belonged to the Bacillus pumilus species, based on the phylogenetic analysis of the 16S rRNA gene, using the maximum-likelihood method.