Bioremediation is a process used to treat contaminated media, including water, soil and subsurface material, by altering environmental conditions to stimulate growth of microorganisms and degrade the target pollutants. Cases where bioremediation is commonly seen is oil spills, soils contaminated with acidic mining drainage, underground pipe leaks, and crime scene cleanups. These toxic compounds are metabolized by enzymes present in microorganisms. Most bioremediation processes involve oxidation-reduction reactions where either an electron acceptor is added to stimulate oxidation of a reduced pollutant or an electron donor is added to reduce oxidized pollutants. Bioremediation is used to reduce the impact of byproducts created from anthropogenic activities, such as industrialization and agricultural processes. In many cases, bioremediation is less expensive and more sustainable than other remediation alternatives. Other remediation techniques include, thermal desorption, vitrification, air stripping, bioleaching, rhizofiltration, and soil washing. Biological treatment, bioremediation, is a similar approach used to treat wastes including wastewater, industrial waste and solid waste. The end goal of bioremediation is to remove or reduce harmful compounds to improve soil and water quality.
Reductive dechlorination is Chemical reaction of chlorinated organic compounds with reductants. The reaction breaks C-Cl bonds, and releases chloride ions. Many modalities have been implemented, depending on the application. Reductive dechlorination is often applied to remediation of chlorinated pesticides or dry cleaning solvents. It is also used occasionally in the synthesis of organic compounds, e.g. as pharmaceuticals.
Biological augmentation is the addition of archaea or bacterial cultures required to speed up the rate of degradation of a contaminant. Organisms that originate from contaminated areas may already be able to break down waste, but perhaps inefficiently and slowly.
Geobacter is a genus of Proteobacteria. Geobacter species are anaerobic respiration bacterial species which have capabilities that make them useful in bioremediation. Geobacter was found to be the first organism with the ability to oxidize organic compounds and metals, including iron, radioactive metals, and petroleum compounds into environmentally benign carbon dioxide while using iron oxide or other available metals as electron acceptors. Geobacter species are also found to be able to respire upon a graphite electrode. They have been found in anaerobic conditions in soils and aquatic sediment.
Cometabolism is defined as the simultaneous degradation of two compounds, in which the degradation of the second compound depends on the presence of the first compound. This is in contrast to simultaneous catabolism, where each substrate is catabolized concomitantly by different enzymes. Cometabolism occurs when an enzyme produced by an organism to catalyze the degradation of its growth-substrate to derive energy and carbon from it is also capable of degrading additional compounds. The fortuitous degradation of these additional compounds does not support the growth of the bacteria, and some of these compounds can even be toxic in certain concentrations to the bacteria.
Dehalococcoides is a genus of bacteria within class Dehalococcoidia that obtain energy via the oxidation of hydrogen and subsequent reductive dehalogenation of halogenated organic compounds in a mode of anaerobic respiration called organohalide respiration. They are well known for their great potential to remediate halogenated ethenes and aromatics. They are the only bacteria known to transform highly chlorinated dioxins, PCBs. In addition, they are the only known bacteria to transform tetrachloroethene to ethene.
Microbial biodegradation is the use of bioremediation and biotransformation methods to harness the naturally occurring ability of microbial xenobiotic metabolism to degrade, transform or accumulate environmental pollutants, including hydrocarbons, polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), heterocyclic compounds, pharmaceutical substances, radionuclides and metals.
In enzymology, a tetrachloroethene reductive dehalogenase is an enzyme that catalyzes the chemical reaction. This is a member of reductive dehalogenase enzyme family.
A dehalogenase is a type of enzyme that catalyzes the removal of a halogen atom from a substrate.
In situ chemical reduction (ISCR) is a new type of environmental remediation technique used for soil and/or groundwater remediation to reduce the concentrations of targeted environmental contaminants to acceptable levels. It is the mirror process of In Situ Chemical Oxidation (ISCO). ISCR is usually applied in the environment by injecting chemically reductive additives in liquid form into the contaminated area or placing a solid medium of chemical reductants in the path of a contaminant plume. It can be used to remediate a variety of organic compounds, including some that are resistant to natural degradation.
Zerovalent iron (ZVI) is jargon that describes forms of iron metal used for Groundwater remediation. ZVI serves as a reducing agent.
Dehalococcoides is a class of Chloroflexi, a phylum of Bacteria. It is also known as the DHC group.
Dehalobacter restrictus is a species of bacteria in the phylum Firmicutes. It is strictly anaerobic and reductively dechlorinates tetra- and trichloroethene. It does not form spores; it is a small, gram-positive rod with one lateral flagellum. PER-K23 is its type strain.
Desulfitobacterium dehalogenans is a species of bacteria. They are facultative organohalide respiring bacteria capable of reductively dechlorinating chlorophenolic compounds and tetrachloroethene. They are anaerobic, motile, Gram-positive and rod-shaped bacteria capable of utilizing a wide range of electron donors and acceptors. The type strain JW/IU-DCT, DSM 9161, NCBi taxonomy ID 756499.
Desulfitobacterium hafniense is a species of gram positive bacteria, its type strain is DCB-2T..
Desulfuromonas michiganensis is a species of tetrachloroethene-reducing, acetate-oxidizing anaerobic bacteria.
Dehalogenimonas lykanthroporepellens is an anaerobic, Gram-negative bacteria in the phylum Chloroflexi isolated from a Superfund site in Baton Rouge, Louisiana. It is useful in bioremediation for its ability to reductively dehalogenate chlorinated alkanes.
Adsorbable Organic Halides (AOX) is a measure of the organic halogen load at a sampling site such as soil from a land fill, water, or sewage waste. The procedure measures chlorine, bromine, and iodine as equivalent halogens, but does not measure fluorine levels in the sample.
Reductive dehaholagenses (EC 1.97.1.8) are a group of enzymes utilized in organohalide respiring bacteria. These enzymes are mostly attached to the periplasmic side of the cytoplasmic membrane and play a central role in energy-conserving respiratory process for organohalide respiring bacteria by reducing organohalides. During such reductive dehalogenation reaction, organohalides are used as terminal electron acceptors. They catalyze the following general reactions:
Sam Hay is a chemist from New Zealand and a Reader in the Department of Chemistry at The University of Manchester. His research in general is based on computational chemistry and theoretical chemistry, specifically on the areas of In silico Enzymology, quantum mechanics roles in biological processes, kinetic modelling of complex reactions and high pressure spectroscopy.
