Abstract

Industrial effluents containing heavy metals pose significant environmental and health risks. Traditional remediation methods are often expensive and generate secondary pollutants. In recent years, bioremediation techniques utilizing microorganisms have gained attention for their potential to remove or transform heavy metals from contaminated environments. This article explores the microbial factors involved in the bioremediation of heavy metals from industrial effluents. Microorganisms with inherent metal tolerance mechanisms can survive in high metal concentrations. Metalbinding proteins, such as metallothioneins, sequester heavy metals, preventing their toxic effects. Metal-accumulating microorganisms adsorb and immobilize heavy metals within their biomass, removing them from effluents. Microbes also transform heavy metals into less toxic or more easily removable forms. Bioprecipitation involves the precipitation of heavy metals as insoluble compounds. Microbial-produced extracellular polymeric substances facilitate the formation of metal precipitates, reducing their solubility and mobility.

Biomineralization refers to microbial-induced formation of metal-containing minerals. Certain bacteria generate sulphides that react with heavy metal ions, forming stable and less toxic metal sulphide minerals. Microbial redox reactions involve the transfer of electrons between microorganisms and heavy metals, transforming toxic metals into less harmful forms. Synergistic interactions among microbial communities enhance bioremediation efficiency. Metabolic cooperation involves the exchange of metabolites, supporting the growth and metal tolerance of other microorganisms. Quorum sensing enables coordinated gene expression for heavy metal resistance or transformation. Biofilm formation enhances resistance to toxic substances and increases metal accumulation capacity.