Exploring the Potential of Bacillus velezensis, an Endophytic Bacteria Isolated from Alternanthera philoxeroides for Plant Growth Promotion and Bioremediation Properties

The current work was done to analyse the bioremediation and plant growth promotion (PGP) traits of endophytic bacteria isolated from Alternanthera philoxeroides from Bellandur Lake, Bangalore, India. Twenty-nine endophytic bacteria were isolated and tested for their PGP traits like indole acetic acid (IAA), ammonia, nitrogen fixation, 1-aminocyclopropane-1- carboxylate (ACC) deaminase production, phosphate solubilization etc. Endophytic bacterium, BEBAphL1 obtained from leaves of A. philoxeroides exhibited significant plant growth promotion properties and the isolate was identified as Bacillus velezensis OQ874364 using 16S rRNA sequencing. The bacterium showed potential IAA, ammonia production, nitrogen fixation, phosphate solubilization, and ACC deaminase production. The results indicate that this endophyte is promising as a growth-promoting inoculant, reducing the reliance on chemical inputs in conventional agricultural practices while enhancing nutrient uptake and stress resilience in plants. B. velezensis exhibited tolerance to high levels of chromium (500 mg/L) and NaCl (15%) and was also able to decolourize Congo red by 70% at 0.005% concentration of dye. Characterization of dye samples pre- and post-bacterial treatment was done using Fourier-transform infrared spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS) analysis. The findings of the study indicate that B. velezensis shows promise as a plant growth stimulator capable of withstanding heavy metal exposure and breaking down dyes.