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New Strategy of Phytoremediation

#G-718


Elaboration of a New Strategy of Phytoremediation and Long-Term Protection of the Environment Polluted by Hydrocarbons

Tech Area / Field

  • ENV-RED/Remediation and Decontamination/Environment
  • BIO-REM/Bioremediation/Biotechnology
  • BIO-CHM/Biochemistry/Biotechnology

Status
8 Project completed

Registration date
10.05.2001

Completion date
02.02.2006

Senior Project Manager
Ryzhova T B

Leading Institute
Durmishidze Institute of Biochemistry and Biotechnology, Georgia, Tbilisi

Collaborators

  • University of Cambridge, UK, Cambridge\nUniversity of Pennsylvania, USA, PA, Philadelphia\nCNRS / Institut National de la Recherche Agronomique, France, Montpellier\nInstitut fur Umweltforschung, Universitat Dortmund, Germany, Dortmund\nFrontier Research Center for the Global Environment Protection, Meisei University, Japan, Tokyo

Project summary

The main goal of the present project is the elaboration of biochemical criteria for the selection of plants according to their ability to absorb and deeply degrade hydrocarbons, which is the basis of a new strategy of environmental phytoremediation and maintenance of the ecological balance.
The beginning of the XXI century is characterized by a clearly expressed tendency of enhanced contamination of the environment. As a result of chemical synthesis several million tons of chemicals are annually produced in the world. The huge amount of these chemicals is concentrated in biosphere and significantly affects the ecological balance.
Recent investigations of the molecular mechanisms of pollutant detoxification by plants and microorganisms have been intensively studied (Salt, D.E., Smith, R.D. and Raskin, J. Phytoremediation. Annu. Rev. Plant Physiol. Plant Mol. Biol. 1998, 49, 643-668). Phytoremediation, based on plants’ ability to absorb and transform a wide spectrum of organic toxicants, including aliphatic and aromatic hydrocarbons of natural gas and oil, is a cost-effective and advanced ecotechnology (Glass, D.J. Current Market Trends in Phytoremediation. International Journal of Phytoremediation, 1999, 1, 1-8). In contrast to existing technologies of environment purification, phytoremediation provides considerable remediation, ensuring maintenance of the natural ecological balance (Korte, F., Kvesitadze G., et al., Review: Organic toxicants and plants. Ecotoxicology and Environmental Safety. 2000, 47, 1-26). One of the main advantages of phytoremediation, as a wide scale industrial technology, consists in the following: as a result of deep enzymatic degradation to CO2 or cell regular metabolites, all carbon atoms of the pollutants participate in carbon natural circulation.
The efficiency of technologies based on plants’ phytoremediational characteristics is defined by a plant’s ability to degrade toxicant molecule to carbon dioxide. Such potential is characteristic for plants with a full set of enzymes, participating in the processes of toxicant oxidative degradation.
By coordinated action of oxidative enzymes, the degradation of the carbon skeleton of a toxicant to standard cell metabolites is achieved. These enzymes – cytochrom P450-containing monooxygenase, peroxidase and phenoloxidase are those marker proteins, which mainly determine a plant’s detoxificational potential.
For the last 40 years, the Durmishidze Institute of Biochemistry and Biotechnology, Academy of Sciences of Georgia, has studied molecular mechanisms of detoxification of organic pollutants, particularly: aliphatic, aromatic, including polycyclic aromatic carcinogenic hydrocarbons, pesticides of different classes, nitrogen-containing organic compounds, etc, by plants.
Over 130 publications were devoted to the investigation of this problem. Proteins, the primary products of coding loci of genomous DNA, define peculiarities of metabolism in plants. They are reliable criteria for evaluation of the functional significance of genes responsible for their synthesis. Therefore, exposure of direct products of plant growth genes, expressible at definite conditions – proteins in the electrophoretic spectra, functionally linked with the hydrocarbons’ oxidative degradational potential, allows fast and reliable selection of the most promising plants for phytoremediation purposes. At the same time the results of these investigations could be successfully used for recombinant DNA manipulations, for the creation of new plant varieties with increased ecological potential.
Project realization will advance basic understanding of the transformation and detoxification of organic xenobiotics in plants.
Expected results
· To reveal the plant varieties, which actively absorb and degrade hydrocarbons to carbon dioxide or standard cell intermediates.
· To elucidate molecular mechanisms of hydrocarbon degradation in higher plants, consisting of consecutive enzymatic oxidative reactions for hydrocarbons of different chemical structure and to state the toxicity of formed intermediates.
· To determine the protein spectra of plants characterized by increased or slightly expressed ability of hydrocarbon degradation. To state the existence of proteins – markers, responsible for deep metabolic transformation of hydrocarbons.
· To work out biochemical criteria for the fast selection of plants for phytoremediational purposes, according to their ability to conduct deep degradation of hydrocarbons.
· To elaborate a new strategy of phytoremediation, consisting of purposeful selection of plants on the basis of biochemical criteria.
The practical significance of these results consists in the use of the elaborated method of plant selection for their successful application in phytoremediation technologies.
Meeting ISTC goals
According to the goals and objectives of the ISTC, 57% of so-called “weapons scientists” will participate in realization of this peaceful project - fundamental/applied research in environmental protection.
Practical implementation
The project has national as well as international significance. The experimental results of the project will facilitate the solution of a problem connected with the danger of environmental pollution in Georgia with hydrocarbons at realization of the international projects: Baku-Tbilisi-Ceyhan Main Export Oil Pipeline, Supsa Oil Terminal. The project will contribute to ecological security of the Eurasian Transport Corridor (TRASECA).
Taking into account that territories around gas and oil-pipelines, highways and railroads, and proving grounds all over the world are contaminated by the same pollutants, it is obvious that the new strategy of phytoremediation could be successfully used in other countries worldwide.The implementation of the project envisages the execution of the following tasks:
1. To reveal plants, capable of actively absorbing gaseous (C1-C4) and liquid (C5-C8) alkanes and aromatic hydrocarbons (benzene, toluene, benzo[a]pyrene, naphtalene).
2. To state pathways of hydrocarbon oxidative degradation to carbon dioxide or regular endogenous compounds.
3. To establish activities and possibilities of induction of oxidative enzymes – cytochrom P450-dependent monooxygenase, peroxidase and polyphenoloxidase in plants with deep degradation ability of hydrocarbons.
4. To investigate the effect of different concentrations of hydrocarbons on metabolic and energetic processes and the ultrastructural organization of a plant cell.
5. On the basis of conducted investigations, to reveal proteins, as a markers of plants characterized by high potential to conduct deep metabolic transformation of hydrocarbons.

The study of plants’ ability to absorb and degrade hydrocarbons will be carried out by the method of radioactive indication using radioactive preparations labeled by carbon 14C. This well approved method allows most precise determination of the degree of hydrocarbon absorption, and the depth of degradation of the carbon skeleton.

The hydrocarbon transformation will be carried out by the methods of thin-layer, gas-liquid and high performance liquid (HPLC) chromatography, IR and UV spectroscopy.


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