Mechanisms of Bacterial Resistance to Heavy Metals: A Mini Review

Because of rising levels of heavy metal pollution in the environment, microbial resistance to heavy metals has become an increasing concern. Heavy metal resistance in bacteria is typically achieved through a combination of passive and active mechanisms, including heavy metal sequestration, efflux, or transformation within the microbial cell. During the efflux mechanism, a membrane protein's energy-dependent ion efflux from the cell is necessary for heavy metal removal. Understanding the physicochemical parameters of the environment, structure and diversity of microbial communities, nature and concentration of heavy metals is critical for developing effective strategies for the remediation of heavy metal-contaminated sites. Many microbes play a significant part on functioning ecosystem more especially in the biogeochemical cycling of heavy metals by removing the metals from the environment. As, Pb, Cd, and Hg are among heavy metals that are associated with the most common ecologically hazardous metals that can be toxic to microbes and still nature has evolved few groups of microbes that were found to resist the effect of heavy metals while thriving within their ecosystem such as Pseudomonas sp., Escherichia coli and Serratia marcescens that can resist Hg. Pseudomonas putida, Cupriavidus necator, Exiguobacterium sp., Bacillus aquimaris, Bacillus cereus and Alcaligenes sp. can also resist Cu, Cd, Pb, Cr and Ni. The exposure of local and regional soil with heavy metal pollution due to smelting causes which poses major environmental issues that is currently on rise in human ecosystem. Therefore, studying the mechanisms of bacterial resistance to heavy metal is critical for developing strategies to reduce the environmental impact of heavy metal pollution.