Metals and Extremophilic Bacteria in Mining Environments: A Systematic Review

Industrial activities have contributed substantially to the global economy but have also resulted in the release of hazardous substances into the environment. This systematic review aimed to identify extremophilic or extremotolerant bacteria capable of surviving high metal concentrations and actively remediating elevated levels of Cd, Cr, Cu, Fe, Pb, and Zn. Following the PRISMA guidelines, a qualitative systematic review was conducted in the Web of Science and Scopus databases for studies published between 2000 and 2025 (last search: 5 January 2026). The synthesized dataset revealed distinct ecological and functional roles across different taxonomic levels. At the family level, Carnobacteriaceae, Cyclobacteriaceae, and Erythrobacteraceae were predominantly associated with high metal tolerance ("exposed" profiles) in alkaline environments. Conversely, at the genus level, Acidithiobacillus, Phenobacterium, Microbulbifer, and Roseobacter demonstrated high active remediation capacities in acidic settings through bioleaching, precipitation, or biosorption. Species such as Bacillus subtilis and Acidithiobacillus ferrooxidans exhibit a dual profile combining environmental tolerance and high bioremediation performance. These findings highlight methodologically heterogeneous studies, necessitating standardized experimental validation prior to large-scale technological deployment.