Technical Session 1:

Title:         Assay and Optimization of Plant Growth Promoting Phosphate Solubilizing Ability of Diazotrophic Bacteria from Rhizosphere of Eragrostis Cynosuroides
Authors:     Chander Prabha, Sonali Kumari, Abha Singh Sushma Kumari, Shilpi Kiran
Abstract:   A large number of diazotrophic bacteria, present in the soil are known to solubilize phosphate to make it available to the plants, influencing plant growth and development through direct or indirect mechanisms. Such phosphate solubilizing bacteria (PSB) increase bioavailability of phosphate and reduce the dependency on chemical fertilizers. In the present study, seven bacteria (DR1…..DR7) were isolated from rhizosphere of grass, Eragrostis cynosuroides, growing on road sides of Danapur, Patna, Bihar, India. They were screened for their nitrogen fixing as well as phosphate solubilizing properties. Amongst the seven isolates, DR2 showed maximum phosphate solubilising activity (40.36 mgl-1), along with its diazotrophy (60.23 nmol C2H4 formed mg-1 protein h-1). Therefore, DR2 was selected to optimize the cultural conditions for phosphate solubilization. The highest activity was observed at 96 h incubation (41.32 mgl-l), temperature 35˚C (44.51 mgl-1) and pH 7 (45.86 mgl-l). Glucose (46.12 mgl-1) and ammonium sulphate (48.16 mgl-1) as carbon and nitrogen sources, respectively appeared to be best for phosphate solubilization. The seeds of barley (Hordeum vulgare) and yellow mustard (Brassica oleracea) were inoculated with DR2 for glass house experiment and the seedlings (3 weeks old) witnessed enhanced growth, in terms of root, shoot lengths and biomass. The isolate, DR2 was identified as Bacillus subtilis DR2 (KP455653) on the basis of 16s rRNA gene sequencing and phylogenetic analysis. The findings suggest that B. subtilis DR2 has the potential to be exploited as bioinoculant.

Keywords:  Rhizobacteria, Diazotrophy, PSB, DR2, 16s rRNA Sequencing.
Pages:        032-040

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