A study on exopolysaccharides production, biosorption, and detoxification properties of Lysinibacillus fusiformis KMNTT-10 in growth media treated with Pb 2+ ions

The growth, biosorption efficiency (%), and exopolysaccharides (EPS) production of Lysinibacillus fusiformis KMNTT-10 strain in nutrient broth containing Pb 2+ ions was investigated in this study. Further, the interaction of Pb 2+ ions with KMNTT-10 biomass and the state of the adsorbed Pb 2+ ions were studied by FTIR, SEM–EDS, and XRD analysis. Experimental results showed that the growth and biosorption efficiency of KMNTT-10 strain for Pb 2+ ions were highest at pH 6.0, 96 h incubation time, and 10 mg/L of initial Pb 2+ ions concentration. Also, the biosorption efficiency and EPS production of KMNTT-10 strain for Pb 2+ ions were dependent on their growth in nutrient broth containing Pb 2+ ions. Under nutrient broth containing 10, 50, and 100 mg/L of Pb 2+ ions, the biosorption efficiency of KMNTT-10 strain for Pb 2+ ions was 98.2, 82.9, and 68.5%, respectively, and their EPS production was 0.42, 0.36, 0.29 mg/100 mL, respectively. From this, it is apparent that bacterial growth, biosorption capacity, and EPS production are interrelated and depend on the concentration of Pb 2+ ions in nutrient broth. Characterization studies revealed that the KMNTT-10 strain exhibited a distorted cell surface when grown under Pb 2+ ions treated broth, and they adsorbed the Pb 2+ ions via an ionic interaction and transformed it into PbS form either intra/extracellularly. The present study’s results suggested that the biosorption and biotransformation potential of KMNTT-10 strain for Pb 2+ ions could be used in metal removal applications at the pilot scale.