Physiological and biomolecular interventions in the bio-decolorization of Methylene blue dye by <i>Salvinia molesta</i> D. Mitch

Methylene blue, a cationic dye as a pollutant is discharged from industrial effluent into aquatic bodies. The dye is biomagnified through the food chain and is detrimental to the sustainability of aquatic flora. Despite of number of physico-chemical techniques of dye removal, the use of aquatic flora for bio-adsorption is encouraged. Thus, we used <i>Salvinia molesta</i> D. Mitch in bio-reduction of methylene blue on concentrations of 0, 10, 20, and 30 mg L^-1 through 5 days with biosorption kinetics. The dye removal was concentration-dependent, maximized at 2 days with 30 mg L^-1 which altered the relative growth rate (44%) of plants. Biosorption recorded 71% capacity at optimum pH (8.0), 24 h reducing major bond energies of amide, hydroxyl groups, etc. Bioaccumulation of dye changed potassium content (446%) under maximum dye concentration modifying tissues for dye sequestration. Reactive oxygen species were altered on dye reduction by oxidase (33%) with redox homeostasis by enzymes. Plants altered the metabolism with over accumulation of polyamines (51%), abscisic acids (448%), and phosphoenolpyruvate carboxylase (83%) on dye reduction. Thus, this study is rationalized with a sustainable approach where aquatic ecosystems can be decontaminated from dye toxicity with the exercise of bioresources like <i>Salvinia molesta</i> D. Mitch as herein.