Isolation and Characterization of a New Bacillus licheniformis Strain for Bioleaching Heavy Metals

ntroduction: Increased usage and improper management of electronic wastes results in immense environmental pollution. Although conventional techniques are well known for removing heavy metals from the environment, their high cost and severe environmental consequences indicates urgent requirement of cost-effective methods of heavy metals uptake. Bioaccumulation can be considered as an alternative to the traditional methods in terms of their cost effectiveness and maximum recovery of the metal ions. Materials and Methods: This study deals with the isolation of heavy metals tolerant Gram-positive bacterial strain, Bacillus licheniformis JAJ3 and its application in bioaccumulation of copper, lead and nickel and bioleaching of heavy metals from electronic waste. For this purpose, 16S rRNA sequencing was performed to identify the bacterial strain. The accumulation study was carried out in liquid medium and analyzed using atomic absorption spectroscopy (AAS). Bioleaching activity was checked using one-step procedure. For bioleaching studies of heavy metals, printed circuit boards (PCBs) were used as a source of electronic wastes. Scanning electron microscopy and energy dispersive spectroscopy were used to record the changes before and after experimental procedures. Results: The organism was able to accumulate 98.6% copper, 64.6% lead and 57.3% nickel. The bioaccumulation reaction followed pseudo second order kinetics model (R2 value 0.92, 0.92, 0.99 for copper, lead and nickel bioaccumulation respectively). Efficient bioleaching activity was shown by the strain. Conclusions: The experimental analyses confirmed that the strain is efficient in bioleaching heavy metals from electronic wastes and thus can be used in the management of electronic wastes.