Abstract

A number of stress tolerant plant growth promoting phosphate solubilizing bacteria were isolated from soils collected from different geo-climatic zones of India. Maximum numbers of these bacteria were found in Aurawan soil, followed by National Botanical Garden, Mukhateshwar and Nainital. Among these bacteria, strain NBRI1213 showed maximum phosphate solubilization activity (984 µg/mL) and was identified as Serratia marcescensby 16S rRNA full gene sequencing. It showed tolerance to wide range of temperature (30 to 50°C), salt (0 - 5% NaCl) and pH (7 - 10). Salicylic acid was found to be present in addition to oxalic, citric acid and acetic acid in culture filtrate. In a micro plot study, inoculation of maize seeds with phosphate solubilizing S. marcescens NBRI1213 showed better response than control. It did not only improve the quality but increased the soluble phosphorus content and enhanced the phosphate-solubilizing microbial populations of the soil. S. marcescens NBRI1213 isolated from alkaline soil was found to be an efficient phosphate solublizer and can be used as potential plant growth promoting rhizobacteria bio-inoculant in agricultural systems.

Key words: Phosphate solubilization, Serratia marcescens, stress tolerance, rhizosphere competence, maize.