Low temperature phosphate solubilization and plant growth promotion by psychrotrophic bacteria, isolated from Indian Himalayan Region

Four hundred and fifty bacterial isolates from a culture collection of high altitude bacteria isolated from different regions of Indian Himalaya were screened for their low temperature phosphate solubilization activity at 4 and 10°C using plate based assay on Pikovskaya (PVK) agar. Five isolates (identified as psychrotrophic Pseudomonas species) showing solubilization efficiency >350 were selected for in vitro quantification studies. In PVK broth the isolates effectively solubilized phosphate at both the incubation temperature. The isolates also exhibited other plant growth promotion abilities such as production of siderophores, indole acetic acid and antagonized two test fungus viz.Alternaria alternata and Fusarium oxysporum. Under growth chamber pot assay at 10-15°C the isolates exhibited increased plant growth and mineral nutrition of wheat indicating their functionality at lower temperatures. Addition of insoluble phosphate to the inoculated soil significantly increased the growth parameters in all the cases. The present study is important with respect to enumerating microbial diversity of the colder regions as well as understanding the potential biotechnological applications of native microbes.