PLANT GROWTH PROMOTING AND PHYTOSTIMULATORY POTENTIAL OF Bacillus Subtilis AND Bacillus Amyloliquefaciens

Root colonizing bacteria that exert beneficial effects on plant growth have been defined as plant growth promoting rhizobacteria (PGPR). The present study aimed to the production of indole-3-acetic acid (IAA) and siderophore in WR-W2 and MR-AI strains under in vitro condition. Synthesis of IAA and siderophore was checked in presence of different carbon sources in JNFb medium amended with L-tryptophan (100 μg/ml) and iron limited M9 medium, respectively. Time course study and simultaneous production of IAA and siderophore was performed in the strain MR-AI and WR-W2. Malate followed by acetate was found as the most suitable sole carbon source for both the IAA and siderophore production by the strain. Siderophore production was inhibited above 20μM concentration of Fe (III). Catecholate type of siderophore production was identified in the culture supernatant of both the strain. Furthermore, significant increase in rice plant (Pusa sugandha III) growth response was observed, when the strains were used as bioinoculum under gnotobiotic condition, in presence of L-tryptophan (100μg/ml). 16S rRNA gene sequence reveals strains MR-AI as Bacillus amyloliquefaciens and WR-W2 as Bacillus subtilis. Strain WR-W2 was found to be more efficient as compared to MR-AI in terms of its capability to produce IAA and siderophore. Therefore, strain MR-AI and WR-W2 could be further applied as bioinnoculum in different formulation in seeds or crop fields for sustainable agricultural systems.