Utilization of agro-industrial waste for biosurfactant production under submerged fermentation and its synergistic application in biosorption of Pb²⁺

The biosurfactant production process was optimized using raw orange peel extract (ST reduction = 33.04 dyne cm⁻¹; biosurfactant yield = ~3.7 g L⁻¹) and the extracted metabolite was characterized in terms of its nature, and class/family. To the best of our knowledge, a first report utilizing biowaste as a sole carbon substrate for simultaneous biosurfactant production and Pb²⁺ removal under submerged fermentation by Bacillus haynesii strain E1. The results depicted the extracted biosurfactant to be of lipopeptide nature belonging to surfactin family having 50 mg L⁻¹ of CMC. The crude biosurfactant was found to be tensioactive at temperature 70 °C, 6% salt concentration, and varying pH range. The biosurfactant-producing bacterium effectively remediated Pb²⁺ (high MIC = 2200 mg L⁻¹) with a maximum adsorption capacity of 196.08 mg g⁻¹. The biosorption mechanism followed Langmuir (R² = 0.9724) and Pseudo second-order adsorption kinetics (R² = 0.9996; 200 mg L⁻¹).