Microbial detoxification of heavy metals in wastewater: Mechanisms, current perspectives and emerging bioremediation strategies

The rapid expansion of industrial activities and their consequent discharge into the environment is causing severe threats to ecosystems and public health. Toxic heavy metals such as cadmium, arsenic, copper, chromium, lead, cobalt, and others are of particular concern. It has become a long-term challenge to treat such wastes polluted with these persisting contaminants. They bioaccumulate in food chains and therefore possess harmful effects. Microorganisms serve as effective biological tools for heavy metal removal and detoxification from water and wastewater. The role of microbes in biotransformation of heavy metals into lesser toxic forms has been explored in this review. Bacterial-mediated mechanisms such as biosorption, bioleaching, bioaccumulation, bioprecipitation, and biotransformation involved in the detoxification of heavy metals have been discussed. Biotechnological implication of metal-contaminated waste has been highlighted with reference to use of bioreactor technology, nanobiotechnology, genomics, heavy metal accumulating plants, and mechanism of metal removal and tolerance in microbes. Understanding these processes further contributes to the development of approaches which are effective yet sustainable in remediating wastewaters contaminated with heavy metals. • Bacterial mechanisms for detoxification of heavy metals in wastewater matrices. • Summarizes recent advances in microbial remediation strategies. • Integrates data on bacterial strains, removal efficiencies and pathways. • Identifies research gaps and future directions for sustainable remediation.