Elucidating the Synergistic Role of Bacillus velezensis DW2115 in multimetal Remediation and Mangrove Growth Promotion

Abstract

Soil contamination with chromium [Cr( and lead Pb ( primarily from anthropogenic activities, constitutes a serious ecological and public health concern Plant growth promoting rhizobacteria ( alleviate metal toxicity by reducing metal bioavailability, while enhancing plant growth This study assessed the potential of Bacillus velezensis DW 2115 for enhancing Avicennia officinalis L growth under multimetal stress The strain isolated from Bhitarkanika mangrove forest, demonstrated tolerance to co exposure of Cr(VI) and Pb ( upto 500 ppm Confocal microscopy revealed maximal biofilm biomass formation at 300 ppm 19 43 0 50 µm 3 µm 2 which declined at 500 ppm ATR FTIR and zeta spectroscopy showed marked alterations in EPS functional groups upon interaction with metals, while CD spectroscopy indicated a 96 84 decrease in helix, with an increase in β sheet at 500 ppm Moreover, multimetal stress induced upregulation of DNA repair mutT mutL mutS and antioxidant katX sodB trxA genes, with biofilm forming genes tasA epsC maximally expressed at 300 ppm Further, bacterial inoculation improved mangrove height and vigor index, accompanied by elevated catalase 45 50 and guaiacol peroxidase 12 60 activities under multimetal stress Thus, B velezensis DW 2115 presents remarkable potential for promoting mangrove growth in heavy metal contaminated soils.