Differential response of two endophytic bacterial strains inoculation on biochemical and physiological parameters of Bacopa monnieri L. under arsenic stress conditions

The accumulation of arsenic (As), in medicinal herbs, is detrimental due to its adverse effects on plant metabolism and consumer health. The present study aims to examine the ameliorative effect of two arsenate [As(V)] reduc-ing endophytic bacterial strains (CIMAP-A4 and BAC-7) on As induced photo-toxicity in Bacopa monnieri. The inoculation of BAC-7 and CIMAP-A4 in As contaminated soil showed an increase in biomass (26 and 84%) and reduced As accumulation in plant tissue (42% and 88%) respectively. Strain CIMAP-A4 improved tolerance in-dex, arsenate reductase activity, plant nutrient uptake (Zn, Mg, Ca), and non-protein thiol synthesis than BAC-7 under As stress.The indole acetic acid production and biofilm formation potential under As(V) stress (10 mg L-1) only in CIMAP-A4 could be the reason for the higher ameliorating effect. The strain CIMAP-A4 was iden-tified as Paenibacillus sp. and could be a good option for As-induced stress mitigation in plants and successful bioremediation.