Selection and identification of phosphate-potassium solubilizing bacteria from the area around the limestone mining in cirebon quarry

Abstract

Phosphorus (P) and potassium (K) are essential for the growth and development of plants. Most of phosphate and potassium are bound in the form of rocks P or K-minerals which not be directly absorbed by plants. The utilization of microbes including Phosphate Solubilizing Bacteria (PSB) and Potassium Solubilizing Bacteria (KSB) is deemed as an alternative to address the issue of P and K availability. The objective of the research was to select and identify the phosphate-potassium solubilizing bacteria and measure the quantitative estimation of solubilized P and K. Phosphatepotassium solubilizing bacteria were collected and regrown using dot method on Pikovskaya solid medium to solubilize P and on Aleksandrov solid medium to solubilize K, incubated for 7 days at room temperature. The QC3.a.1 and QC3.d.5 showed the highest solubilization index on Pikovskaya medium containing Ca 3 (PO 4) 2, while QC3.a.2 produced the highest amount of soluble phosphate. The QC3.a.2 showed the best of potassium solubilizing activity based on clear zone formation, while QC3.a.1 had the best ability in feldspar hydrolyzation. The three strains were Gram-negative bacteria. Phylogenetic analysis based on 16S rRNA gene sequence showed that isolate QC3.a.1 was closely related to Burkholderia, isolate QC3.a.2 was closely related to Serratia and isolate QC3.d.5 was closely related to Pseudomonas putida.