Bioprospecting of Multi Trait Plant Growth Promoting Bacillus altitudinis from Phosphate Rich Soil

Abstract

Phosphate Solubilizing Bacteria (PSB) has the natural ability to liberate unavailable phosphorus (as a result of microbial metabolism extracellularly) from soil, rocks, and mines thereby increasing its availability for plants. The main mechanism behind this is the production of mineral dissolving compounds, such as organic acids, protons, hydroxyl ions, and CO2. The current study was conducted to explore the potential of a phosphate solubilizing bacteria which are isolated from rock phosphate mine in Rajasthan for enhancing the growth of Zea mays (maize) plants. Out of total of 137 bacterial isolates, one bacterial isolate RJ-11 was found to have multiple plant growth promoting (PGP) properties. Its phosphate solubilization ability was observed with solubility index (PSI) of 5.15. The potential isolate RJ-11 was found to solubilize tri calcium phosphate (Ca3(PO4)2) at a rate of 790.67 mg L-1. RJ-11 was found positive for potash solubilization, zinc solubilization, and siderophore production. On the basis of morphological and molecular characterization, isolate RJ-11 was identified as Gram positive bacterium, Bacillus altitudinis. LabID-B197 was assigned to B. altitudinis for further greenhouse pot experiments. Greenhouse pot experiments demonstrated that maize plants inoculated with B197 incorporated more phosphate which was observed as increase in germination percentage, increased shoot length (155%) and root length (45%), and much higher biomass weights than those plants without any added bacteria or controls. The result of present study indicates that B. altitudinis is a unique bacterium with multiple plant growth promoting properties and could act as potential bio fertilizer to improve the plant growth and develop cost-effective and sustainable agriculture practices.