THE POTENTIAL OF PHOSPHATE-SOLUBILIZING BACTERIA FROM THE EGGPLANT FIELDS

The present study aims to identify the diversity and the efficiency of phosphate-solubilizing bacteria (PSB) with a strong potential as bio-inoculums from eggplant fields. Phosphorus is considered as the principal yield-limiting nutrient along with nitrogen. Accordingly it is a primary constraint to plant growth in many terrestrial ecosystems especially, in acid sandy soils with high levels of P fixation by Fe and Al oxides. The potential of phosphate solubilizing bacteria (PSB) to increase soluble P by enhancing solubilization of insoluble P compounds was isolated and evaluated in this experiment. Six different PSB strains isolated from eggplant fields were screened for their efficiency in P solubilization. The PSB isolated from eggplant field soils solubilized 770-1,548 mg/L of P. Stepwise multiple regression analysis and P solubility kinetics indicated that the major mechanism of P solubilization by PSB is the pH reduction through the release of organic acids. Especially, Klebsiella pneumoniae strain M-AI-2 isolate code Ek04 and Gluconacetobacter sp. isolate code Ek01 in the eggplant field seem to have the capacity to solubilize insoluble forms of AlPO₄ and FePO₄ which are the main forms of insoluble phosphates in acid sandy soils.