ABSTRACT

Mercury pollution, resulting from the combustion of fossil fuels and various industrial activities, has significant ecological consequences, affecting both aquatic and terrestrial ecosystems. The process of biosorption, where microorganisms selectively absorb and adsorb solutes onto their cell surfaces, plays a crucial role in mercury removal from the environment. Bacteria, algae, fungi, yeasts, and biofilms are the primary microbial candidates involved in biosorption. Bioaccumulation in microorganisms is another essential phenomenon for mercury detoxification. Microbes gradually accumulate mercury within their cells through uptake and storage processes, with intracellular sequestration occurring through the interactions with various cellular components. Bioprecipitation facilitates the removal of mercury ions from solution by forming insoluble metal compounds through microbial-mediated precipitation processes. Bioleaching plays a key role in transforming mercury forms in the environment by solubilizing heavy metals from solid matrices, making them available for subsequent microbial processes. Biovolatilization is a nonmetabolic process that converts toxic inorganic contaminants into less toxic organic and volatile compounds, reducing the risk of mercury accumulation in food chains and subsequent human exposure. Mercuric reductase and organomercurial lyase are enzymatic systems involved in mercury detoxification, with mercuric reductase reducing mercury ions to their elemental form and organomercurial lyase cleaving carbon-mercury bonds in organic mercury compounds. Microorganisms regulate genetic expression to optimize detoxification processes based on environmental mercury concentrations. Horizontal gene transfer enables the dissemination of mercury resistance genes among bacteria, contributing to their adaptation to diverse environments. Understanding these mechanisms offers opportunities for bioremediation strategies, harnessing microbial capabilities to address environmental pollution challenges.