College of Materials Science and Engineering, Chongqing University, Chongqing, 400044, China.
Institute of Environmental Science and Engineering, School of Metallurgy and Environment, Central South University, Changsha, 410083, China.
Chem Commun (Camb). 2024 Oct 22;60(85):12315-12332. doi: 10.1039/d4cc03722g.
Heavy metals are extensively discharged through various anthropogenic activities, resulting in an environmental risk on a global scale. In this case, microorganisms can survive in an extreme heavy metal-contaminated environment detoxification or resistance, playing a pivotal role in the speciation, bioavailability, and mobility of heavy metals. Therefore, studies on the mechanism for the microbial transformation of heavy metals are of great importance and can provide guidance for heavy metal bioremediation. Current research studies on the microbial transformation of heavy metals mainly focus on the single oxidation, reduction and methylation pathways. However, complex microbial transformation processes and corresponding bioremediation strategies have never been clarified, which may involve the inherent physicochemical properties of heavy metals. To uncover the underlying mechanism, we reclassified heavy metals into three categories based on their biological transformation pathways, namely, metals that can be chelated, reduced or oxidized, and methylated. Firstly, we comprehensively characterized the difference in transmembrane pathways between heavy metal cations and anions. Further, biotransformation based on chelation by low-molecular-weight organic complexes is thoroughly discussed. Moreover, the progress and knowledge gaps in the microbial redox and (de)methylation mechanisms are discussed to establish a connection linking theoretical advancements with solutions to the heavy metal contamination problem. Finally, several efficient bioremediation strategies for heavy metals and the limitations of bioremediation are proposed. This review presents a solid contribution to the design of efficient microbial remediation strategies applied in the real environment.
重金属通过各种人为活动广泛排放，对全球范围内的环境构成风险。在这种情况下，微生物能够在极端重金属污染的环境中生存并进行解毒或抵抗，在重金属的形态、生物可利用性和迁移性方面发挥着关键作用。因此，研究微生物对重金属的转化机制具有重要意义，并可为重金属的生物修复提供指导。目前，关于重金属微生物转化的研究主要集中在单一的氧化、还原和甲基化途径上。然而，复杂的微生物转化过程和相应的生物修复策略从未得到阐明，这可能涉及重金属的固有物理化学性质。为了揭示其潜在机制，我们根据生物转化途径将重金属分为三类，即可以螯合、还原或氧化以及甲基化的金属。首先，我们全面描述了重金属阳离子和阴离子跨膜途径的差异。进一步深入探讨了基于低分子量有机配合物螯合的生物转化。此外，还讨论了微生物氧化还原和（去）甲基化机制的进展和知识空白，以建立将理论进展与解决重金属污染问题的方法联系起来的联系。最后，提出了几种有效的重金属生物修复策略以及生物修复的局限性。本综述为在实际环境中设计有效的微生物修复策略提供了坚实的贡献。
