Thermophiles in Nanosized Biocalcification: a Novel Approach for Heavy metal Remediation

Biodeposition of minerals is a prevalent occurrence in the biological realm, facilitated by various organisms such as bacteria, protists, fungi, and plants. Calcium carbonate is one such mineral that precipitates naturally as a consequence of microbial metabolic processes. This study investigates an innovative approach for carbon dioxide (CO2) sequestration by utilizing thermophilic microorganisms (bacteria and enzymes) in the conversion of CO ₂ into CaCO3 and methanol. The thermophilic bacterial strains of Bacillus licheniformis and enzymes formaldehyde dehydrogenase (FalDH) and alcohol dehydrogenase (ADH) were screened for their ability of microbial-induced carbonate precipitation (MICP). The research focuses on identifying the various optimal conditions, such as CO2 concentration, bacterial concentration, pH, time, and temperature, for CaCO3 biosynthesis. Both strains of Bacillus licheniformis found to be the most efficient in biocalcification. Notably, these microbes also redirected their great potential towards the heavy metal remediation strategy. Heavy metals are non-biodegradable, and as they persist in the environment, they accumulate and magnify in ecosystems, intensifying the harmful effects on living organisms. Thermophilic bacterial strain excellently removes Pb (II) ions from aqueous solutions of MICP with 90% efficiency, and nanosized (35.85 nm, 38.58 nm) biominerals were formed. These comparative findings provide valuable insights for optimizing bio-based carbonate production in CO2 sequestration technology.