Inorganic phosphate solubilization by phosphate solubilising fungi isolated from acidic soils

Abstract

The experiment was conducted to evaluate the native phosphate solubilizing fungi on inorganic phosphate solubilization in the acidic soils of Jharkhand, India. Mineral phosphate solubilizing activities of three fungal isolates were tested in tricalcium phosphate and ferric phosphate medium by analyzing the possible phosphorus release and phosphatase activity from 5th, 10th and 15th day of incubation. Maximum P release was observed on 5th and 10th day of incubation in ferric phosphate and tricalcium phosphate medium, respectively, by all the isolates. Among the isolates, Aspergillus niger induced highest P release of 635 and 695 μg ml-1 and resulted in 75 and 77% P solubilisation in tricalcium phosphate and ferric phosphate medium, respectively. The pH of the culture filtrate medium gradually decreased with the progress of incubation and maximum decrease was observed between 5- 10th day of incubation by all the fungal species. The highest peak of acid phosphatase activity in culture filtrates of fungal isolates were observed on 5th and 10th day of incubation in ferric phosphate and tricalcium phosphate medium, respectively. The highest acid phosphatase activity of 73 U was induced both by Aspergillus niger and Trichoderma viride in tricalcium phosphate medium. However, the highest acid phosphatase activity in ferric phosphate medium was 51 U induced by A. niger. Among the isolates, A. niger was more efficient in solubilising the inorganic P followed by T. viride and Penicillium chrysogenum.