Pentachlorophenol
2,4,5-Trichlorophenoxyacetic Acid
Herbicides
Desulfitobacterium
Dioxins
Biodegradation, Environmental
Fungicides, Industrial
Cyclodextrins
Water Purification
Water Pollutants, Chemical
Decolorization and detoxification of extraction-stage effluent from chlorine bleaching of kraft pulp by Rhizopus oryzae. (1/308)
Rhizopus oryzae, a zygomycete, was found to decolorize, dechlorinate, and detoxify bleach plant effluent at lower cosubstrate concentrations than the basidiomycetes previously investigated. With glucose at 1 g/liter, this fungus removed 92 to 95% of the color, 50% of the chemical oxygen demand, 72% of the adsorbable organic halide, and 37% of the extractable organic halide in 24 h at temperatures of 25 to 45 degrees C and a pH of 3 to 5. Even without added cosubstrate the fungus removed up to 78% of the color. Monomeric chlorinated aromatic compounds were removed almost completely, and toxicity to zebra fish was eliminated. The fungal mycelium could be immobilized in polyurethane foam and used repeatedly to treat batches of effluent. The residue after treatment was not further improved by exposure to fresh R. oryzae mycelium. (+info)Initial reactions in the biodegradation of 1-chloro-4-nitrobenzene by a newly isolated bacterium, strain LW1. (2/308)
Bacterial strain LW1, which belongs to the family Comamonadaceae, utilizes 1-chloro-4-nitrobenzene (1C4NB) as a sole source of carbon, nitrogen, and energy. Suspensions of 1C4NB-grown cells removed 1C4NB from culture fluids, and there was a concomitant release of ammonia and chloride. Under anaerobic conditions LW1 transformed 1C4NB into a product which was identified as 2-amino-5-chlorophenol by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry. This transformation indicated that there was partial reduction of the nitro group to the hydroxylamino substituent, followed by Bamberger rearrangement. In the presence of oxygen but in the absence of NAD, fast transformation of 2-amino-5-chlorophenol into a transiently stable yellow product was observed with resting cells and cell extracts. This compound exhibited an absorption maximum at 395 nm and was further converted to a dead-end product with maxima at 226 and 272 nm. The compound formed was subsequently identified by 1H and 13C NMR spectroscopy and mass spectrometry as 5-chloropicolinic acid. In contrast, when NAD was added in the presence of oxygen, only minor amounts of 5-chloropicolinic acid were formed, and a new product, which exhibited an absorption maximum at 306 nm, accumulated. (+info)Superficial buffer barrier and preferentially directed release of Ca2+ in canine airway smooth muscle. (3/308)
We examined cytosolic concentration of Ca2+ ([Ca2+]i) in canine airway smooth muscle using fura 2 fluorimetry (global changes in [Ca2+]i), membrane currents (subsarcolemmal [Ca2+]i), and contractions (deep cytosolic [Ca2+]i). Acetylcholine (10(-4) M) elicited fluorimetric, electrophysiological, and mechanical responses. Caffeine (5 mM), ryanodine (0.1-30 microM), and 4-chloro-3-ethylphenol (0.1-0.3 mM), all of which trigger Ca2+-induced Ca2+ release, evoked Ca2+ transients and membrane currents but not contractions. The sarcoplasmic reticulum (SR) Ca2+-pump inhibitor cyclopiazonic acid (CPA; 10 microM) evoked Ca2+ transients and contractions but not membrane currents. Caffeine occluded the response to CPA, whereas CPA occluded the response to acetylcholine. Finally, KCl contractions were augmented by CPA, ryanodine, or saturation of the SR and reduced when SR filling state was decreased before exposure to KCl. We conclude that 1) the SR forms a superficial buffer barrier dividing the cytosol into functionally distinct compartments in which [Ca2+]i is regulated independently; 2) Ca2+-induced Ca2+ release is preferentially directed toward the sarcolemma; and 3) there is no evidence for multiple, pharmacologically distinct Ca2+ pools. (+info)Earthworm egg capsules as vectors for the environmental introduction of biodegradative bacteria. (4/308)
Earthworm egg capsules (cocoons) may acquire bacteria from the environment in which they are produced. We found that Ralstonia eutropha (pJP4) can be recovered from Eisenia fetida cocoons formed in soil inoculated with this bacterium. Plasmid pJP4 contains the genes necessary for 2,4-dichlorophenoxyacetic acid (2,4-D) and 2, 4-dichlorophenol (2,4-DCP) degradation. In this study we determined that the presence of R. eutropha (pJP4) within the developing earthworm cocoon can influence the degradation and toxicity of 2,4-D and 2,4-DCP, respectively. The addition of cocoons containing R. eutropha (pJP4) at either low or high densities (10(2) or 10(5) CFU per cocoon, respectively) initiated degradation of 2,4-D in nonsterile soil microcosms. Loss of 2,4-D was observed within the first week of incubation, and respiking the soil with 2,4-D showed depletion within 24 h. Microbial analysis of the soil revealed the presence of approximately 10(4) CFU R. eutropha (pJP4) g-1 of soil. The toxicity of 2,4-DCP to developing earthworms was tested by using cocoons with or without R. eutropha (pJP4). Results showed that cocoons containing R. eutropha (pJP4) were able to tolerate higher levels of 2,4-DCP. Our results indicate that the biodegradation of 2, 4-DCP by R. eutropha (pJP4) within the cocoons may be the mechanism contributing to toxicity reduction. These results suggest that the microbiota may influence the survival of developing earthworms exposed to toxic chemicals. In addition, cocoons can be used as inoculants for the introduction into the environment of beneficial bacteria, such as strains with biodegradative capabilities. (+info)Heat-induced expression and chemically induced expression of the Escherichia coli stress protein HtpG are affected by the growth environment. (5/308)
Differences in expression of the Escherichia coli stress protein HtpG were found following exposure of exponentially growing cells to heat or chemical shock when cells were grown under different environmental conditions. With an htpG::lacZ reporter system, htpG expression increased in cells grown in a complex medium (Luria-Bertani [LB] broth) following a temperature shock at 45 degrees C. In contrast, no HtpG overexpression was detected in cells grown in a glucose minimal medium, despite a decrease in the growth rate. Similarly, in pyruvate-grown cells there was no heat shock induction of HtpG expression, eliminating the possibility that repression of HtpG in glucose-grown E. coli was due to catabolite repression. When 5 mM phenol was used as a chemical stress agent for cells growing in LB broth, expression of HtpG increased. However, when LB-grown cells were subjected to stress with 10 mM phenol and when both 5 and 10 mM phenol were added to glucose-grown cultures, repression of htpG expression was observed. 2-Chlorophenol stress resulted in overexpression of HtpG when cells were grown in complex medium but repression of HtpG synthesis when cells were grown in glucose. No induction of htpG expression was seen with 2, 4-dichlorophenol in cells grown with either complex medium or glucose. The results suggest that, when a large pool of amino acids and proteins is available, as in complex medium, a much stronger stress response is observed. In contrast, when cells are grown in a simple glucose mineral medium, htpG expression either is unaffected or is even repressed by imposition of a stress condition. The results demonstrate the importance of considering differences in growth environment in order to better understand the nature of the response to an imposed stress condition. (+info)Fraction of electrons consumed in electron acceptor reduction and hydrogen thresholds as indicators of halorespiratory physiology. (6/308)
Measurements of the hydrogen consumption threshold and the tracking of electrons transferred to the chlorinated electron acceptor (f(e)) reliably detected chlororespiratory physiology in both mixed cultures and pure cultures capable of using tetrachloroethene, cis-1, 2-dichloroethene, vinyl chloride, 2-chlorophenol, 3-chlorobenzoate, 3-chloro-4-hydroxybenzoate, or 1,2-dichloropropane as an electron acceptor. Hydrogen was consumed to significantly lower threshold concentrations of less than 0.4 ppmv compared with the values obtained for the same cultures without a chlorinated compound as an electron acceptor. The f(e) values ranged from 0.63 to 0.7, values which are in good agreement with theoretical calculations based on the thermodynamics of reductive dechlorination as the terminal electron-accepting process. In contrast, a mixed methanogenic culture that cometabolized 3-chlorophenol exhibited a significantly lower f(e) value, 0.012. (+info)Biodegradation of pentachlorophenol in a continuous anaerobic reactor augmented with Desulfitobacterium frappieri PCP-1. (7/308)
In this work, a strain of anaerobic pentachlorophenol (PCP) degrader, Desulfitobacterium frappieri PCP-1, was used to augment a mixed bacterial community of an anaerobic upflow sludge bed reactor degrading PCP. To estimate the efficiency of augmentation, the population of PCP-1 in the reactor was enumerated by a competitive PCR technique. The PCP-1 strain appeared to compete well with other microorganisms of the mixed bacterial community, with its population increasing from 10(6) to 10(10) cells/g of volatile suspended solids within a period of 70 days. Proliferation of strain PCP-1 allowed for a substantial increase of the volumetric PCP load from 5 to 80 mg/liter of reaction volume/day. A PCP removal efficiency of 99% and a dechlorination efficiency of not less than 90.5% were observed throughout the experiment, with 3-Cl-phenol and phenol being observable dechlorination intermediates. (+info)Reductive dehalogenation and conversion of 2-chlorophenol to 3-chlorobenzoate in a methanogenic sediment community: implications for predicting the environmental fate of chlorinated pollutants. (8/308)
Biotransformation of 2-chlorophenol by a methanogenic sediment community resulted in the transient accumulation of phenol and benzoate. 3-Chlorobenzoate was a more persistent product of 2-chlorophenol metabolism. The anaerobic biotransformation of phenol to benzoate presumably occurred via para-carboxylation and dehydroxylation reactions, which may also explain the observed conversion of 2-chlorophenol to 3-chlorobenzoate. (+info)Chlorophenols are a group of chemical compounds that consist of a phenol ring substituted with one or more chlorine atoms. They are widely used as pesticides, disinfectants, and preservatives. Some common examples of chlorophenols include pentachlorophenol, trichlorophenol, and dichlorophenol.
Chlorophenols can be harmful to human health and the environment. They have been linked to a variety of adverse health effects, including skin and eye irritation, respiratory problems, damage to the liver and kidneys, and an increased risk of cancer. Exposure to chlorophenols can occur through contact with contaminated soil, water, or air, as well as through ingestion or absorption through the skin.
It is important to handle chlorophenols with care and to follow proper safety precautions when using them. If you are concerned about exposure to chlorophenols, it is recommended that you speak with a healthcare professional for further guidance.
Pentachlorophenol is not primarily a medical term, but rather a chemical compound with some uses and applications in the medical field. Medically, it's important to understand what pentachlorophenol is due to its potential health implications.
Pentachlorophenol (PCP) is an organochlorine compound that has been widely used as a pesticide, wood preservative, and disinfectant. Its chemical formula is C6HCl5O. It is a white crystalline solid with a distinct, somewhat unpleasant odor. In the environment, pentachlorophenol can be found in soil, water, and air as well as in various organisms, including humans.
Pentachlorophenol has been associated with several potential health risks. It is classified as a probable human carcinogen by the International Agency for Research on Cancer (IARC) and as a possible human carcinogen by the United States Environmental Protection Agency (EPA). Exposure to pentachlorophenol can occur through inhalation, skin contact, or ingestion. Potential health effects include irritation of the skin, eyes, and respiratory tract; damage to the liver and kidneys; neurological issues; and reproductive problems.
In a medical context, pentachlorophenol might be relevant in cases where individuals have been exposed to this compound through occupational or environmental sources. Medical professionals may need to assess potential health risks, diagnose related health issues, and provide appropriate treatment.
2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) is a synthetic auxin, or plant growth regulator, that has been used as an herbicide. It was a component of Agent Orange, which was used as a defoliant during the Vietnam War. 2,4,5-T has been banned in many countries due to concerns about its toxicity and potential health effects.
It is important to note that exposure to 2,4,5-T has been linked to various health issues, including developmental and reproductive problems, as well as an increased risk of cancer. It is classified as a possible human carcinogen by the International Agency for Research on Cancer (IARC).
It's also important to note that 2,4,5-T is not used in medical field, it's mainly used as herbicide and defoliant.
2-Methyl-4-chlorophenoxyacetic acid is a synthetic auxin, which is a type of plant hormone. It is often used as a herbicide to control broadleaf weeds in crops such as corn and wheat. It works by causing uncontrolled growth in the targeted plants, ultimately leading to their death. It is important to note that this compound is not typically used in human medicine.
Glycolates are a type of chemical compound that contain the group COOCH2, which is derived from glycolic acid. In a medical context, glycolates are often used in dental and medical materials as they can be biodegradable and biocompatible. For example, they may be used in controlled-release drug delivery systems or in bone cement. However, it's important to note that some glycolate compounds can also be toxic if ingested or otherwise introduced into the body in large amounts.
Herbicides are a type of pesticide used to control or kill unwanted plants, also known as weeds. They work by interfering with the growth processes of the plant, such as inhibiting photosynthesis, disrupting cell division, or preventing the plant from producing certain essential proteins.
Herbicides can be classified based on their mode of action, chemical composition, and the timing of their application. Some herbicides are selective, meaning they target specific types of weeds while leaving crops unharmed, while others are non-selective and will kill any plant they come into contact with.
It's important to use herbicides responsibly and according to the manufacturer's instructions, as they can have negative impacts on the environment and human health if not used properly.
'Desulfitobacterium' is a genus of anaerobic, gram-positive bacteria that are capable of dehalogenating and reducing chlorinated organic compounds. These organisms play a significant role in the bioremediation of contaminated environments, as they can transform harmful pollutants into less toxic forms. The name 'Desulfitobacterium' is derived from the Latin words "de," meaning "from," "sulfur," referring to the sulfur-containing compounds these bacteria use for energy, and "bacterium," meaning "rod" or "staff."
Some notable species within this genus include:
* Desulfitobacterium dehalogenans: This species is well-known for its ability to reductively dechlorinate a wide range of chlorinated organic compounds, including polychlorinated biphenyls (PCBs) and trichloroethylene (TCE).
* Desulfitobacterium hafniense: This species is capable of reducing various halogenated compounds, such as tetrachloroethene (PCE), TCE, and polychlorinated phenols. It can also use nitrate, sulfate, or metal ions as electron acceptors for energy metabolism.
* Desulfitobacterium frappieri: This species is known to dechlorinate chlorinated ethenes, such as PCE and TCE, and can also reduce iron(III) and manganese(IV) compounds.
These bacteria are typically found in anaerobic environments, such as soil, groundwater, sediments, and the gastrointestinal tracts of animals. They play a crucial role in maintaining the balance of these ecosystems by breaking down complex organic compounds and contributing to nutrient cycling.
Dioxins are a group of chemically-related compounds that are primarily formed as unintended byproducts of various industrial, commercial, and domestic processes. They include polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and certain polychlorinated biphenyls (PCBs). Dioxins are highly persistent environmental pollutants that accumulate in the food chain, particularly in animal fat. Exposure to dioxins can cause a variety of adverse health effects, including developmental and reproductive problems, immune system damage, hormonal disruption, and cancer. The most toxic form of dioxin is 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD).
Chlorobenzoates are a group of chemical compounds that consist of a benzene ring substituted with one or more chlorine atoms and a carboxylate group. They are derivatives of benzoic acid, where one or more hydrogen atoms on the benzene ring have been replaced by chlorine atoms.
Chlorobenzoates can be found in various industrial applications, such as solvents, plasticizers, and pesticides. Some chlorobenzoates also have medical uses, for example, as antimicrobial agents or as intermediates in the synthesis of pharmaceuticals.
However, some chlorobenzoates can be toxic and harmful to the environment, so their use is regulated in many countries. It's important to handle and dispose of these substances properly to minimize potential health and environmental risks.
Environmental biodegradation is the breakdown of materials, especially man-made substances such as plastics and industrial chemicals, by microorganisms such as bacteria and fungi in order to use them as a source of energy or nutrients. This process occurs naturally in the environment and helps to break down organic matter into simpler compounds that can be more easily absorbed and assimilated by living organisms.
Biodegradation in the environment is influenced by various factors, including the chemical composition of the substance being degraded, the environmental conditions (such as temperature, moisture, and pH), and the type and abundance of microorganisms present. Some substances are more easily biodegraded than others, and some may even be resistant to biodegradation altogether.
Biodegradation is an important process for maintaining the health and balance of ecosystems, as it helps to prevent the accumulation of harmful substances in the environment. However, some man-made substances, such as certain types of plastics and industrial chemicals, may persist in the environment for long periods of time due to their resistance to biodegradation, leading to negative impacts on wildlife and ecosystems.
In recent years, there has been increasing interest in developing biodegradable materials that can break down more easily in the environment as a way to reduce waste and minimize environmental harm. These efforts have led to the development of various biodegradable plastics, coatings, and other materials that are designed to degrade under specific environmental conditions.
Industrial fungicides are antimicrobial agents used to prevent, destroy, or inhibit the growth of fungi and their spores in industrial settings. These can include uses in manufacturing processes, packaging materials, textiles, paints, and other industrial products. They work by interfering with the cellular structure or metabolic processes of fungi, thereby preventing their growth or reproduction. Examples of industrial fungicides include:
* Sodium hypochlorite (bleach)
* Formaldehyde
* Glutaraldehyde
* Quaternary ammonium compounds
* Peracetic acid
* Chlorhexidine
* Iodophors
It's important to note that some of these fungicides can be harmful or toxic to humans and other organisms, so they must be used with caution and in accordance with safety guidelines.
Cyclodextrins are cyclic, oligosaccharide structures made up of 6-8 glucose units joined together in a ring by alpha-1,4 glycosidic bonds. They have a hydrophilic outer surface and a hydrophobic central cavity, which makes them useful for forming inclusion complexes with various hydrophobic guest molecules. This property allows cyclodextrins to improve the solubility, stability, and bioavailability of drugs, and they are used in pharmaceutical formulations as excipients. Additionally, cyclodextrins have applications in food, cosmetic, and chemical industries.
Water purification is the process of removing or reducing contaminants in water to make it safe and suitable for specific uses, such as drinking, cooking, irrigation, or medical purposes. This is typically achieved through physical, chemical, or biological methods, or a combination thereof. The goal is to eliminate or reduce harmful substances like bacteria, viruses, parasites, heavy metals, pesticides, and other pollutants that can cause illness or negatively impact human health, aquatic life, or the environment.
The specific purification methods used may vary depending on the nature of the contaminants and the desired level of purity for the intended use. Common techniques include filtration (using various types of filters like activated carbon, ceramic, or reverse osmosis), disinfection (using chemicals like chlorine or UV light to kill microorganisms), sedimentation (allowing particles to settle and be removed), and distillation (heating water to create steam, which is then condensed back into pure water).
Chemical water pollutants refer to harmful chemicals or substances that contaminate bodies of water, making them unsafe for human use and harmful to aquatic life. These pollutants can come from various sources, including industrial and agricultural runoff, sewage and wastewater, oil spills, and improper disposal of hazardous materials.
Examples of chemical water pollutants include heavy metals (such as lead, mercury, and cadmium), pesticides and herbicides, volatile organic compounds (VOCs), polychlorinated biphenyls (PCBs), and petroleum products. These chemicals can have toxic effects on aquatic organisms, disrupt ecosystems, and pose risks to human health through exposure or consumption.
Regulations and standards are in place to monitor and limit the levels of chemical pollutants in water sources, with the aim of protecting public health and the environment.
Beta-cyclodextrins are cyclic, oligosaccharide structures made up of 6-8 glucose units linked by α-1,4 glycosidic bonds. They have a hydrophilic outer surface and a hydrophobic central cavity, making them useful for forming inclusion complexes with various hydrophobic molecules in aqueous solutions. This property is exploited in pharmaceutical applications to improve drug solubility, stability, and bioavailability. Additionally, beta-cyclodextrins can be chemically modified to enhance their properties and expand their uses.
Chlorophenol - Wikipedia
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