Phosphate Solubilizing Activity of Some Bacterial Strains Isolated from Chemical Pesticide Exposed Agriculture Soil

–Phosphorus is one of the most vital macronutrients required for the growth and development of plants. A large number of microorganisms present in the rhizosphere are known to solubilize and make available the insoluble phosphorus in the available form to the plants. A total of fifty phosphate solublizing bacterial colonies were isolated on the Pikovskaya’s (PKV) agar medium, containing insoluble tri-calcium phosphate (TCP), from repeatedly chemical pesticide used agriculture soil of Dhanbad area. The colonies showing clear halo zones around the bacterial growth were considered as phosphate solubilizers. Out of 50 bacterial isolates, 10 isolates showing highest phosphate solubilisation index (SI) ranged from 1.4 – 3.0 were selected for the further study as qualitative as well as quantitative performance. Among these 10 potent isolates, two strains S2 and S30 showed the maximum phosphate solubilization index of 3.1 and 3.0 in agar plates along with high soluble phosphate production of 373.07 mgL and 368.58 mgL in broth culture, respectively. Isolates S2 and S30 belong to genus Bacillus sp. and Pseudomonas sp. as identified by their morphological and biochemical characteristics, respectively. In all the phosphate solubilizing bacterial isolates, decrease in pH was observed ranging 3.2 to 6.2 from initial pH of 6.8 to 7.2. The decrease in pH of the culture medium there by solublizing the insoluble TCP indicated the production of various organic acids by the culture. Keywords––Phosphate solublizing bacteria, pesticide, soil, Bacillus sp., Pseudomonas sp.