Selected Pesticides Inhibit Phosphate Solubilizing Activity of Gluconacetobacter Sp. and Burkholderia plantarii

Native Phosphate solubilizing bacteria (PSB) possessing the ability to solubilize insoluble inorganic phosphates were isolated from rhizosphere soils of crop plants. Eighty one potential PSBs thus obtained were quantitatively screened for phosphate solubilization. The amount of P solubilized for different bacteria varied between 11.38-72.97 mg/100 mL. Of these, two bacteria (PSB 12 and 73) found to be efficient phosphate solubilizers. These organisms were characterized on the basis of morphological, cultural and biochemical characteristics as Gluconacetobacter sp. and Burkholderia plantarii. The isolates were further tested for their tolerance to pesticides, Ekalux, Tagban, Sevin, Metacid and Hinosan. The two organisms showed remarkable difference in pesticide tolerance. Their minimum inhibitory concentration (MIC) values range between 48-3125 μg/mL. Quantitative estimation of soluble P in pesticide containing Pikovaskaya’s broth indicates that pesticides have an inhibitory effect on phosphate solubilizing activity.