Phosphorus is an essential plant macronutrient present in the soil. Only a small portion of phosphorus in soil is taken up by plants and the rest of it becomes unavailable to plants as it is immobilized. Phosphate solubilizing microorganisms play a vital role in converting the insoluble form of phosphates to the soluble form. The present paper reports the solubilization of tricalcium phosphate, rock phosphate, single super phosphate, zinc phosphate and aluminum phosphate by Piriformospora indica with the production of organic acids as well as acid phosphatase. The amount of phosphate released (4.73 mg ml) and titratable acidity (0.12%) was found to be the highest in the case of single super phosphate as compared to other phosphate sources. High performance liquid chromatography (HPLC) revealed the presence of oxalic acid, lactic acid, citric acid and succinic acid in the media. Highest phosphatase activity was observed with the cell membrane extract of the organism in the presence of zinc phosphate.

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Plant growth promotion through versatile microorganisms inhabiting the rhizospheric region of the soil has emerged as a sustainable approach in improving the crop productivity and crop health management. The present study reports the isolation and characterization of halotolerant as well as drought tolerant isolates that possess exceptional plant growth promotional attributes. Out of 32 isolates obtained, 13 isolates exhibited excellent plant growth promotional attributes such as phosphate solubilization, phytohormone production, siderophore production etc. Among 13 isolates tested for stress tolerance studies, two isolates Mulberry -1 and Ragi-7 were able to tolerate both drought and saline stresses and were further identified as Bacillus licheniformis and Bacillus wudalianchiensis based on biochemical and molecular techniques. Antibiosis activity of both the isolates tested against two important plant pathogens Fusarium oxysporum and Phomopsis vexans was found to be positive. Bacillus licheniformis and Bacillus wudalianchiensis were further tested for their efficacy to solubilize five different inorganic phosphate sources. The amount of phosphate liberated was found to be highest (3562 mgml-1  and 1894 mgml-1) with diammonium phosphate followed by single super phosphate  and tricalcium phosphate with respect to Bacillus licheniformis  and Bacillus wudalianchiensis. Zea mays L. seeds treated with the culture filtrate of both the isolates were cultivated on Murashige-Skoog medium under In-vitro conditions. Bacillus wudalianchiensis was found to be better compared to Bacillus licheniformis with respect to plant growth promotional aspects as they were able to increase the root and shoot length of Zea mays L. under In-vitro conditions. Application of the multifaceted capabilities of unexplored halotolerant strain of Bacillus wudalianchiensis could open up a new avenue in plant biotechnology.