Isolation of phytate-degrading microorganisms with inorganic phosphate solubilizing activity (biofertilizers) for plant growth enhancement

Abstract

Phosphorus (P) shortage in the soil is a key problem in agricultural output. Phytate (Myo-inositol phosphate), which is stable and unavailable to plants, is abundant in soils, accounting for up to 50% of all organic P. The conversion of phytate to Myo-inositol and phosphate is catalyzed by phytases. Microorganisms that solubilize P, biofertilizers, are common in soils and may play a major role in providing P to plants. Secreted microbial phytases enhancing plant development in terms of phosphorus availability. This study aimed to identify possible phytate degrading microorganisms from the rhizosphere, animal dung, soil, and livestock farms samples collected from farms in Khartoum, Sudan. Modified Luria Bertani and phytase screening media supplemented with wheat bran as a source of phytate were used as selection media. Each sample was serially diluted 10 times, and 100 µl from dilution 103 was distributed onto each of two screening medium plates, cultured aerobically at 37°C for 1 to 4 days, A putative phytate degrading bacterium was detected in isolates with a clear zone around their growing colonies. A total of 17 isolates were obtained, with 15/17 (88%) being bacterial isolates and 2/17 being fungal isolates. Phosphate solubilizing activity was performed on Pikovskaya’s agar plate, and plates were incubated at 37°C for 7 days. The plates were examined for the presence of a halo zone around each isolated culture. out of the 17 isolates, only one Gram-positive Bacilli (isolate AB13) was found to have phosphate solubilizing activity and the ability to liberate P from phytate, suggesting that it could be used as a biofertilizer.