Characterization of culture condition dependent, growth responses of phosphate solubilizing bacteria (Bacillus subtilis DR2) on plant growth promotion of Hordeum vulgare

Phosphorus (P) is one of the essential macro nutrients required for the growth and development of plant. Phosphate solubilising bacteria (PSB) are very effective in improving soil fertility by solubilising insoluble soil P, making them readily available to the plants. In the present work, PSB were isolated from the rhizosphere of Eragrostis cynosuroides on Pikovskaya’s agar media at 30 °C and pH 7. Among positive isolates, the isolate DR2 was selected, based on highest zone of solubilization (15 mm), phosphate solubilization efficiency (150%) and solubilization index (4.5) on 4th day of incubation period. The isolated DR2 was identified as Bacillus subtilis on the basis 16 S rRNA gene sequence (Gene bank Accession Number KP455653). Optimized cultural conditions resulted in maximum P-solubilization after 96 h of incubation at 35 °C in Pikovsakaya’s broth (having 1% TCP) of pH 7.0 with glucose and ammonium sulphate, used as carbon and nitrogen sources, respectively. B. subtilis DR2 significantly enhanced the growth of barley seedlings in terms of seed germination (60%) with percent enhancements in root length (93.71%), shoot length (41.30%) and biomass (22.44%), over control. The strain B. subtilis DR2 can be used as a biofertilizer for a sustainable integrated plant nutrient supply (IPNS) system. © The Author(s) under exclusive licence to Society for Plant Research 2023. corrected publication 2023.