Bioremediation of Heavy Metals by Metagenomic Approaches

Abstract

AbstractDeposition of heavy metals and other contaminating materials in the environment is a ceaseless and inescapable process. Bioaccumulation of heavy metals is extremely harmful to all domains of life. While dealing with heavy metal pollutions, microbes, especially Proteobacteria and Actinobacteria, acclimatize and adapt themselves to contaminated sites through different metabolic activities. Microbial bioremediation through biosorption, bioaccumulation, solubilization, immobilization, transformation, etc. is an innovative, sustainable, cost-effective, and efficient approach for reducing heavy metal toxicity. Since traditional culturable approaches have limitations, metagenomic approaches help uncover the microbes, associated genes, and their functions in heavy metal bioremediation. Rapid improvements in molecular techniques, such as high-throughput DNA sequencing, amplification, cloning, microarrays, and other “-omic” tools, have shown promise in revealing the metabolic diversity and nutrient versatility of microbes living in contaminated environments. Study site selection, sample collection and nucleic acid extraction, genome enrichment, and metagenomic library construction are the key steps in metagenomic research. Starting with a complete understanding of metagenomic screening, several function-based techniques including phenotype-based screening, substrate-induced gene expression (SIGEX), and metabolite-regulated expression (METREX) are used to discover new classes of genes. Bioinformatic tools like MEGAN, CAMERA, MG-RAST, and IMG/M play a variety of roles in the field of metagenomic bioremediation data analysis. Although new findings overcome major difficulties in microbial community analysis, still many activities lack adequate screening methods and have poor expression systems for metagenomes. In spite of these limitations, we could carry out our metagenomic research to evaluate microbial community composition in polluted areas to select effective microbes that can help in heavy metal remediation and to determine how to apply them to enhance the nature-friendly elimination processes.KeywordsBioremediationSustainableHeavy metalsMetagenomicsBioinformaticsMicrobial communityMEGAN