Published Paper Details:

Phosphate availability in soil is limiting factor for the growth of plants. Phosphate solubilising microbes can be implicated as biofertilizers. The phosphate solubilizing microorganism was initially isolated on basic growth medium for fungi and actinomycetes. The screening for phosphate solubilisation of isolates was carried on Pikovskays (PVK) and National Botanical Research Institute phosphate (NBRIP) medium supplemented with 0.5% (W/W) calcium phosphate as the substrate. The effect of different phosphate sources [Ca3(PO4)2, AlPO4, FePO4 and rock phosphate as control] and their concentration, incubation time, temperature and changes in pH of media after the solubilisation of phosphate was analyzed. The screening for phosphate solubilisation potential was based on holo-zone formation on solid medium, while soluble phosphate in the culture filtrate was determined by vandomolybdate method. The isolates Aspergillus niger US11 and Aspergillus terreus US3 could solubilize maximum TCP at a temperature of 30�C while Penicillium sp. US10 solubilize maximum TCP at 25�C. On the other hand the both the potential actinomycetes isolates solubilise TCP at a higher temperature of 35�C. All the fungal isolates showed maximum solubilization of TCP at pH 7 whereas in case of actinomycetes pH 8 was optimum for solubilization. After 144 hrs of growth, maximum solubilisation of TCP equivalent to 1353 mg/ L was demonstrated by the isolate Aspergillus niger US11 when the initial TCP concentration of 7500 mg/L was used in the medium. Aspergillus terreus also showed maximum solubility at the initial concentration of 7500 mg/L, however the growth time was only 96 hrs. The other three strains demonstrated maximum solubilisation of TCP when the initial concentration of TCP was kept at 5000mg/L in the medium. However Actinomycetes sp. reached maximum solubility of phosphate at relatively less time of only 72 hrs. Our finding suggested that all selected isolates can be used for the preparation a biofertilizer for the different crops.