Xenobiotic Biodegradation

• Microorganisms' ability to detoxify xenobiotic compounds lets them survive in toxic environments, using carbon, phosphorus, sulfur, and nitrogen
• Biotransformation is the most effective way to degrade xenobiotic compounds.
• Microorganisms' have unique genes, enzymes, and mechanisms which allows them to degrade xenobiotic materials
• Bacteria and fungi can partially or completely metabolize these substances.
• Cutting-edge methods help understand the molecular mechanisms and pathways to decontaminate xenobiotics.
• This study looks at catabolic genes, enzymes, and techniques to combat xenobiotic compounds via eco-friendly methods.
• Xenobiotic contaminants, enzymes, microorganisms, metagenomics, and sustainability are all keywords related to the study.

Introduction

• Environmental pollution by xenobiotics is a major global issue, because of industrialization and urbanization.
• Xenobiotic contaminants include azodyes, phenolics, polycyclic aromatic hydrocarbons (PAHs), halogenated compounds, personal care products (PCPs), pharmaceuticals' active compounds (PhACs), pesticides, nitroaromatic compounds, triazines, and chlorinated compounds
• Xenobiotics adversely affect the environment because they persist for a long time and biodegrade slowly, or not at all in ecosystems
• When xenobiotics enter the food chain they affect all trophic levels, and harm animal and human health.
• Public interest was sparked in the 1960s leading to the discovery of DDT (dichloro-diphenyl-trichloroethane), and methyl mercury residues in fish and wildlife.
• Pollutants are teratogenic, carcinogenic, mutagenic, and toxic to organisms which necessitates their removal from the environment
• Current physical and chemical methods to degrade xenobiotic compounds include: coagulation, filtration, adsorption, chemical precipitation, electrolysis, and ozonation.
• These methods are not always cost-effective, and due to the lack of space, complicated procedures, strict regulatory requirements, public dissatisfaction, waste disposal issues, and toxic by-products, they can be even more hazardous than original compounds
• Microbial degradation has become the most effective, environmentally safer, and cost-effective method for removing these hazardous compounds
• Bioremediation includes: destruction, eradication, immobilization, or detoxification of various chemical wastes in the environment via microorganisms.
• Bioremediation-related technologies are: phytoremediation, rhizofilteration, bioaugmentation, biostimulation, landfarming, bioreactors, and composting.
• Persistent organic pollutants (POPs) cleanup with microbial enzymes is eco-friendly, cost-effective, and inventive.
• Laws and rules have been created to address xenobiotic issues and many patents are in use in the EU and worldwide to eliminate xenobiotics from the environment
• Implementation in xenobiotic analysis can help scientists, technologists, business leaders, attorneys, policymakers, and researchers access technology updates
• Study aims to convey knowledge on catabolic genes for xenobiotic pollutants and the role of microbial enzymes in detoxification and transformation from various environments

Xenobiotic Pollution and Impact

• Xenobiotic pollution is a global problem caused by anthropogenic activities like urbanization, population expansion, and harmful compounds releasing into the environment
• Polycyclic aromatic hydrocarbons (PAHs), heavy metal ions, pesticides, fertilizers, and oil derivatives are found in soil, sediment, and water
• Scientific and technological advances during the Industrial Revolution led to over-exploitation of resources, destroying ecosystems
• The irrational use of human, veterinary drugs and pharmaceutical waste adds more environmental contamination
• Pharmaceuticals may have little acute environmental toxicity but there is a dearth of evidence about chronic or multi-generational life cycle consequences
• Xenobiotic compounds have hazardous effects on the environment, plants, animals, and humans.

Impact of Xenobiotics on Soil

• Dioxins, 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT), polychlorinated biphenyls (PCBs), chlordane, polycyclic aromatic hydrocarbons (PAHs), and nitroaromatics threaten soil ecosystems in developed nations
• Benzene, nitrobenzene, toluene, xylene, aniline, ethylbenzene, trinitrotoluene/dibenzofurans, chlorinated solvents, cosmetics, parabens, and azodyes can also be xenobiotic in soil
• Anthropogenic activities include: industrial activities, fuel combustion, military movement, use of pesticides, fertilizers, high-production agricultural practices
• Pesticides are chemicals used for crop protection and pest management and are the most widely used toxins in the environment
• Environmental factors like temperature, soil pH, and moisture impact persistent organic pollutants (POPs) in the soil.
• Soil organic matter (SOM) binds xenobiotic compounds.
• Inorganic minerals interact with xenobiotics and help with their transformation.

Impact of Xenobiotics on Water

• Diffusive and point contributions happen due to anthropogenic activities like urban industrial production, transportation, construction, and housing pollute surface and groundwater in urban areas
• Chemical substances and indicators of human activity are present in urban water systems
• In sewage treatment plants, some common xenobiotics sensors must be treated before municipal wastewater discharge into aquatic systems.
• Trace metals, xenobiotic substances, and synthetic organic chemicals are found in water bodies
• Xenobiotics enter water through: airborne particulate deposition, surface water running from roads and land surfaces, inputs from commercial and sewage effluents, fossil fuel products, and solid waste burning
• Substances reach water tables through leaching, which affects aquatic ecosystems' biological integrity.
• Xenobiotic pollutants cause oxidative stress in aquatic organisms and causes oxidative stress with reactive oxygen species and suppresses the antioxidant system.

Impact of Xenobiotics on Plants

• Xenobiotics affect plant's physiology and morphology such as photosynthetic pigments, protein and cysteine content and leaf area
• Xenobiotics cause changes in gene expression, regulation, and signal transduction in higher plants.
• Phytohormone analogs interact with plant hormone receptors and signaling pathways.
• Metals needed for plant growth, like Cu, Zn, Fe, and Mo, have effects at high concentrations.
• Non-essential metals for plant growth, such as Pb, Cd, Hg and As have adverse effects even in low concentrations.
• Xenobiotics casuse DNA damage in plants through reactive oxygen species and oxidative stress.
• Signaling pathways get deregulated in plants by influencing signaling receptors like G-Protein coupled receptors and receptor tyrosine kinase.

Impact of Xenobiotics on Marine Life

• Xenobiotics affect metabolic processes of marine animals and specifically in developing fish embryos which causes morphological and functional abnormalities and growth retardation and sometimes death.
• Dyes and paints are also xenobiotic and stop sunlight penetration and gas exchange even in the traces.
• Pesticides and herbicides leads to pollution and chemicals like organophosphorus, nitrophenols, morpholine, synthetic pyrethroids, and carbamates, are widely used chemicals that contaminate water bodies
• Insecticide such as beta-Cypermethrin is a severe threat to the life of marine life and invertebrates.

Impact of Xenobiotics on Terrestrial Animals

• Xenobiotic exposure occurs through drugs or chemicals as part of veterinarian procedures
• Their toxicity depends on the use and the the animals exposure factors
• Mechanical and chemical properties determine xenobiotic toxicity.
• Xenobiotics and metabolites induce physiological changes in animals by altering immunological functions, cardiovascular indices, or organ systems.
• Ivermectin harms some dog and mouse stains due to a lack of p-glycoprotein.
• Pazufloxacin and meloxicam cause oxidative damage in rabbits.

Impact of Xenobiotics on Human Health

• Xenobiotic assimilation has increased in recent decades in living species.
• These substances may increase allergic reactions, organism mortality, genetic alterations, immune system lowering, metabolic disorders, and disrupts ecosystems
• Ingestion, breathing, dermal contact, or other intravenous routes of exposure to xenobiotics may risk human health.
• Altered human gut microbiomes can lead to dysbiosis and lead to other undesirable issues.
• Imbalance of mutagenic metabolites lead to chronic diseases and cause DNA damage
• The toxicity of xenobiotics is different in each individual due to sensitivity and variability.
• Many chemicals have harmful and irritating effects on various human organs and systems directly and indirectly

Omics Approaches to Combat Xenobiotic Pollution

• Human activities emit xenobiotics, causing pollution and harming humans and ecosystems.
• Certain xenobiotic-degrading

Role of Microorganisms in Xenobiotic Degradation

• Biological organisms can clean up chemical contamination using processes that is known as bioremediation.
• Microbial enzymes include cytochrome P450s, laccases, cellulase, phytase, proteases, and lipases.
• These enzymes degrade aromatic hydrocarbons, dyes and halogenated compounds.

Xenobiotic Degrading Enzymes Associated with Bacteria

• Bacteria can multiply rapidly in harsh conditions and bacterial strains that digest xenobiotics suggest they evolved by accumulating genes for destruction.
• Bacterial species can biodegrade xenobiotic compounds such as DDT, lindane, PCBs, TNT and crystal violet.
• Examination of 16S rRNA and gyrB gene sequences, identified Gordonia sp.

Xenobiotic Degrading Enzymes Associated with Fungi

• Fungi are valuable in organic pollutant remediation they have unique characteristics that make them microorganisms for procedures.
• They reduce pollutant concentrations by adsorbing various contaminants by physically via is a thick cell wall composed of polymers such as cellulose and chitin.
• Fungi are involved in biofuel degrading, environmental management, food, paper, beverages, textile, etc.

Practical Use of Microorganisms in Bioremediation of Xenobiotics

• Patents are relevant to xenobiotic degradation and cover databases produced by the Canadian Intellectual Property Office, German patents, German Patent and Trademark Office, European Patents and Chinese Patents
• Many patent have been created in process patents regarding products and methods
• Due to fast growing technologies and human needs, most of the products are being designed globally and are long-shelf life

Conclusions and Future Perspective

• Omics approaches are an effective way to understand environmental toxicology and its remediation and better understanding of catabolic genes, degradative enzymes, and involved metabolic pathways.
• Molecular techniques tackle the in-depth assessment of microbial communities from gene to molecule and organism
• The omics technique has uncovered many enzymes, especially those produced by unculturable microbes and steps have discovered various biocatalysts that are organically fitted to industrial restrictions
• Resistant microbial technologies must be considered from a practical perspective; however, there is still some controversy on their field applications
• Novel genetically modified strains are needed, nanotechnology and microbe-mediated bioremediation and sustainable policies with support from policy makers.