Phytodegradation, also known as phytotransformation, is the process by which organic pollutants found in the soil or inside plant bodies are broken down by plants or microorganisms. The term “soil enzyme” refers to both extracellular and intracellular enzymes that are produced in the soil by plant roots, other biological cells, and soil microorganisms. These soil enzymes are important in the breakdown of organic matter and the recycling of nutrients. Enzymes can be either extracellular or intracellular, depending on where they are located. Moreover, that, rhizosphere is a unique soil microenvironment in which the characteristics and activities of microorganisms, plant roots, and soil interact in a coordinated way. The root-soil interface inside rhizospher is significantly influenced by rhizosphere soil, and the conversion of soil C, N, P, S, and other nutrient elements is intimately correlated with soil enzyme activity. Enzyme activities isolated from roots, other soil organisms, and the rhizosphere-soil are sensitive markers of heavy metal contamination of the soil and nutrient cycling. Because heavy metals pose serious health risks to humans once they enter the food chain, reclamation of soils tainted by heavy metals has become an environmental concern of great urgency. Many remediation strategies have been tested with differing degrees of success in dealing with this environmental concern. To reduce the amount of pollutants to acceptable levels, biological methods are considered as more effective and biocompatible. Enzyme activities isolated from roots, other microorganisms in the soil, and the rhizosphere-soil are sensitive markers of heavy metal contamination of the soil and nutrient cycling. Lead, chromium, mercury, different polymers, azo dyes, PAHs, and other inorganic and organic pollutants can all be remedied by enzymes. Different enzymes like mono- or dioxygenases, halogenases, peroxidases, phosphotriesterases, hydrolases, laccase, transferases, and oxidoreductases from various species of bacteria, fungi, algae, and plants have been used for the bioremediation of pollutants. A family of enzymes known as ligninolytic enzymes has several uses in bioremediation. The main reason for lead's toxicity is the ROS it produces. The main enzymatic antioxidants are ascorbate–glutathione cycle enzymes, peroxidase, superoxide dismutase, and catalase (Prabhakar et al., Geomicrobiol J 36:894–903, 2019). In the transcriptome experiment the profile gene expression has been studied in above ground parts and in the roots of arabidopsis plants in response to toxic ions of lead. The enzymes, whose gene expression are increased many folds with peroxidase activities, in presence of heavy metal Pb, are summarized here. These antioxidant enzymes can scavenge reactive oxygen species (ROS), when their relative gene expression level is increased as a result of lead metal toxicity (Raj and Das, Environ Chem Ecotoxicol 5:79–85, 2023). During remodeling of plant root cell wall, the uronic acid, production is increased under Pb+2 stress condtion. The carboxyl group fractions of pectins and hemicelluloses are also increased in stressed conditions such as heavy metal toxicity. During lead toxicity condition, these increased number of carboxyl groups, provides more Pb+2 metal ion binding sites in plant cell wall. Thus, metal ion chelation via COO- groups in demethylesterified pectin is made possible by the process of demethylesterification of pectin. Similarly, pectin methylesterase activity is suppressed during heavy metal contamination, but this enzyme is released when metal ions bind to pectin. One of the primary mechanisms by which plants regulate harmful substances, such as As and Cd, is vacuolar sequestration. Several transporter channel proteins are involved in the uptake of Pb+2 ions from soil through plasma membrane of root cell of arabidopsis along with Ca+2 ions. This non-selective cation transporter protein can function as passive transporter of cations between the vacuole and cytosol and plays an important role in vacuolar sequestration of heavy metal lead in arabidopsis.

Role of Enzymes in Phyto-Transformation for Degradation of Organic and Inorganic Pollutants

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发表日期：

2025年

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Anamika Basu

摘要

Phytodegradation, also known as phytotransformation, is the process by which organic pollutants found in the soil or inside plant bodies are broken down by plants or microorganisms. The term “soil enzyme” refers to both extracellular and intracellular enzymes that are produced in the soil by plant roots, other biological cells, and soil microorganisms. These soil enzymes are important in the breakdown of organic matter and the recycling of nutrients. Enzymes can be either extracellular or intracellular, depending on where they are located. Moreover, that, rhizosphere is a unique soil microenvironment in which the characteristics and activities of microorganisms, plant roots, and soil interact in a coordinated way. The root-soil interface inside rhizospher is significantly influenced by rhizosphere soil, and the conversion of soil C, N, P, S, and other nutrient elements is intimately correlated with soil enzyme activity. Enzyme activities isolated from roots, other soil organisms, and the rhizosphere-soil are sensitive markers of heavy metal contamination of the soil and nutrient cycling. Because heavy metals pose serious health risks to humans once they enter the food chain, reclamation of soils tainted by heavy metals has become an environmental concern of great urgency. Many remediation strategies have been tested with differing degrees of success in dealing with this environmental concern. To reduce the amount of pollutants to acceptable levels, biological methods are considered as more effective and biocompatible. Enzyme activities isolated from roots, other microorganisms in the soil, and the rhizosphere-soil are sensitive markers of heavy metal contamination of the soil and nutrient cycling. Lead, chromium, mercury, different polymers, azo dyes, PAHs, and other inorganic and organic pollutants can all be remedied by enzymes. Different enzymes like mono- or dioxygenases, halogenases, peroxidases, phosphotriesterases, hydrolases, laccase, transferases, and oxidoreductases from various species of bacteria, fungi, algae, and plants have been used for the bioremediation of pollutants. A family of enzymes known as ligninolytic enzymes has several uses in bioremediation. The main reason for lead's toxicity is the ROS it produces. The main enzymatic antioxidants are ascorbate–glutathione cycle enzymes, peroxidase, superoxide dismutase, and catalase (Prabhakar et al., Geomicrobiol J 36:894–903, 2019). In the transcriptome experiment the profile gene expression has been studied in above ground parts and in the roots of arabidopsis plants in response to toxic ions of lead. The enzymes, whose gene expression are increased many folds with peroxidase activities, in presence of heavy metal Pb, are summarized here. These antioxidant enzymes can scavenge reactive oxygen species (ROS), when their relative gene expression level is increased as a result of lead metal toxicity (Raj and Das, Environ Chem Ecotoxicol 5:79–85, 2023). During remodeling of plant root cell wall, the uronic acid, production is increased under Pb+2 stress condtion. The carboxyl group fractions of pectins and hemicelluloses are also increased in stressed conditions such as heavy metal toxicity. During lead toxicity condition, these increased number of carboxyl groups, provides more Pb+2 metal ion binding sites in plant cell wall. Thus, metal ion chelation via COO- groups in demethylesterified pectin is made possible by the process of demethylesterification of pectin. Similarly, pectin methylesterase activity is suppressed during heavy metal contamination, but this enzyme is released when metal ions bind to pectin. One of the primary mechanisms by which plants regulate harmful substances, such as As and Cd, is vacuolar sequestration. Several transporter channel proteins are involved in the uptake of Pb+2 ions from soil through plasma membrane of root cell of arabidopsis along with Ca+2 ions. This non-selective cation transporter protein can function as passive transporter of cations between the vacuole and cytosol and plays an important role in vacuolar sequestration of heavy metal lead in arabidopsis.