Mechanistic action of lead removal by the native isolate Bacillus amyloliquefaciens ON261680.1

Abstract

Lead (Pb) is one of the substantial hazard pollutants that cause soil pollution. Bioremediation is an eco-friendly and cost-effective technique that provides a convenient solution for lead removal. In the present study, lead resistant bacterial strains were isolated from industrial effluents contaminated soil with lead minimum inhibitory concentrations reached 15000 ppm. The most resistant isolate was identified by 16S rRNA sequencing as Bacillus amyloliquefaciens ON261680.1. Taguchi statistical design was applied to optimize the environmental and nutritional factors that lead to maximum lead removal. The optimized conditions for the highest lead removal of lead concentration, incubation temperature, incubation time, peptone, yeast, beef extract, NaCl concentrations, pH, inoculum size and inoculum age were 10000 ppm, 30 °C, 96 hrs incubation, 0.5 g, 0.5 g, 1.5 g, 6 g, 9, 15 mL and 48 hrs old culture, respectively. The most significant factors (p < 0.05) were incubation time, pH, lead concentration, and incubation temperature. Mechanistic action was investigated through employing Fourier transform infrared spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM). It was revealed that Bacillus amyloliquefaciens ON261680.1 removed the lead pollutant through bio-adsorption, deposition and complexation on the cell surface. The present study may pave the way to use Bacillus amyloliquefaciens ON261680.1 as an efficient bioremediation tool.