Degradation of Xenobiotic Pollutants: An Environmentally Sustainable Approach

Abstract

The ability of microorganisms to detoxify xenobiotic compounds allows them to thrive in a toxic environment using carbon, phosphorus, sulfur, and nitrogen from the available sources. Biotransformation is the most effective and useful metabolic process to degrade xenobiotic compounds. Microorganisms have an exceptional ability due to particular genes, enzymes, and degradative mechanisms. Microorganisms such as bacteria and fungi have unique properties that enable them to partially or completely metabolize the xenobiotic substances in various ecosystems.There are many cutting-edge approaches available to understand the molecular mechanism of degradative processes and pathways to decontaminate or change the core structure of xenobiotics in nature. These methods examine microorganisms, their metabolic machinery, novel proteins, and catabolic genes. This article addresses recent advances and current trends to characterize the catabolic genes, enzymes and the techniques involved in combating the threat of xenobiotic compounds using an eco-friendly approach.

Keywords: enzymes; metagenomics; microorganisms; sustainability; xenobiotics.

Figure 1

Hazardous effects are caused by direct or indirect exposure of xenobiotic compounds on the environment, plants, animals and human health. Xenobiotics impose ecotoxicological effects on soil organisms, reduce microbial activity, and change the soil’s physico-chemical properties. Releasing xenobiotic compounds to aquatic systems (fresh and marine water) causes eutrophication and severe threats to faunal diversity, including deformities and developmental disorders. In addition, continuous exposure to xenobiotics adversely affects the immune, reproductive and nervous systems and sometimes causes various cancers.

Figure 2

Distinct features of multi-omics technologies in the transformation of xenobiotic compounds. Genomics and metagenomics identify detoxifying enzymes from the whole genome or metagenome sequencing data. RNA seq or transcriptomics data indicate up- and down-regulated genes in response to xenobiotic exposure. Proteomics techniques help to compare the changes in protein profile in the presence and absence of toxic compounds.

Figure 3

Workflow of Metabolomics. The first step of the metabolomics workflow is compound detection; by employing mass spectrometry, NMR, FTIR, etc. The second step is data pre-processing, which aims to improve the signal-to-noise ratio and quality of spectra by noise reduction, baseline correction, peak detection and integration. The third step is data processing through data normalization to reduce technical bias through various software such as MZmine, XCMS, Progenesis QI, etc. The fourth step is a statistical analysis to detect the expressed metabolite, followed by the fifth step, which is function analysis that interconnects metabolites to biological pathways. The final step is integrating metabolomics data to omics data (omics data integration) to understand the mechanism of action.

Figure 4

Microbial enzymes in xenobiotic management. This figure summarizes a few representative enzymes and their corresponding microbial sources involved in xenobiotic detoxification.