Plant growth promotion abilities and formulation of Bacillus megaterium strain B 388 (MTCC6521) isolated from a temperate Himalayan location

Bacillus megaterium strain B388, isolated from rhizosphere soil of pine belonging to a temperate Himalayan location has been characterized. The plant growth promotion and biocontrol properties of the bacterium have been evaluated through petridish and broth based assays. The isolate solubilized tricalcium phosphate under in vitro conditions; maximum activity (166 μg/ml) was recorded at 28°C after 15 days of incubation. Production of indole acetic acid demonstrated in broth assays was another important plant growth promoting character. The bacterium produced diffusible and volatile compounds that inhibited the growth of two phytopathogens viz. Alternaria alternata and Fusarium oxysporum. The carrier based formulations of the bacterium resulted in increased plant growth in bioassays. The rhizosphere colonization and the viability of the cells entrapped in alginate beads were greater in comparison to coal or broth based formulations. The bacterium showed maximum similarity with Bacillus megaterium by 16S rRNA analysis.