Investigation on the Removal of Heavy Metals by Mineral forming bacterial strains isolated from Qatari soils

Heavy metals pollution poses a threat to the environment and human health across the world due to their toxicity, bioaccumulation, lengthy persistence, and bio magnification in the food supply chain. Bio-removal of heavy metals via immobilization through biomineralization by bacteria approach has gotten a lot of interest in recent years. Extracellular polymeric substances (EPS) produced by microbial cells have been evidenced for mediating mineral formation. In this study, the mineral formation and the production of Extracellular Polymeric Substances by Qatari endogenies bacterial strains was investigated. It was observed that in the presence of Cd and Zn, mineral formation was inhibited due to possible competition between these divalent ions and Ca and Mg. However, minerals were formed in the MD1 and in MD1 supplemented with Cu and Ni. The FTIR analysis confirmed various alterations of FTIR peaks indicating possible interactions between the heavy metals and the functional groups of the EPS produced by the studied strains. The EPS produced by the studied strain exhibited variable removal efficiencies (%) of heavy metals. The lowest heavy metal removal efficiency of 0.13% was obtained with Cu by the EPS produced by the mineral forming strain Virgibacillus sp. DF2141. Interestingly, the maximum heavy metal removal efficiency of 31.69% of Zn was achieved the EPS produced by the non-minerals forming strain Virgibacillus halodenitrificans Z4D1. This studly would shed light on the biomineralization process in soils contaminated with heavy metals.