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At least 19 recordsLinked to original sources
PubMed1997

High-performance liquid chromatographic analysis of a linear alkylbenzenesulfonate and its environmental biodegradation metabolites.

A simple and fast method is described for determining a linear alkylbenzenesulfonate (LAS) and its potential sulfonated and unsulfonated metabolites in natural waters. This method includes extraction of 60 ml of water with an octadecyl-bonded silica (C18) mini-column and analysis of the extract by high-performance liquid chromatography. A reversed-phase column with a 0.008 M potassium phosphate buffer (pH 2.2)-acetonitrile gradient as the mobile phase provides the separation. A UV detector, set at 215 nm, is employed.

Alkylation↗
PubMed1995

Organic halogens in the environment: studies of environmental biodegradability and human exposure.

Organic halogens from chlorobleaching of kraft pulp were not as biorecalcitrant as has been assumed. Fifty percent were removed during biotreatment of wastewater, and 50% of the remaining organohalogens faded in fresh water ecosystems in 200 to 400 days. Molecular size seemed not to hinder biodegradation up to sizes of approximately 2000 daltons. Anoxic biodegradation was of prime importance for halomineralization of pulp bleaching organohalogens but could also lead to toxic metabolites such as vinyl chloride from tri- and tetrachloroethene in anoxic soil. Indigenous soil microbes were unable to clean old organohalogen pollution but had converted chlorophenols into polymeric substances, chlorohumus, which were found bioaccumulable by earthworms in spite of the large (up to 5000 g/mole) molecular sizes. Because of the danger of formation of toxic metabolites, the biochemistry of the xenobiotic degradation must be elucidated before active bioremediation is practiced on polluted soil or water. Groundwater pollution by chlorophenols led to increased disease among the exposed population in one well-studied case. Two further cases of potential environmental health impact are described.

Biodegradation, Environmental↗
PubMed1987

Naphthalene biodegradation in environmental microcosms: estimates of degradation rates and characterization of metabolites.

Naphthalene biodegradation was investigated in microcosms containing sediment and water collected from three ecosystems which varied in past exposure to anthropogenic and petrogenic chemicals. Mineralization half-lives for naphthalene in microcosms ranged from 2.4 weeks in sediment chronically exposed to petroleum hydrocarbons to 4.4 weeks in sediment from a pristine environment. Microbiological analysis of sediments indicated that hydrocarbon-utilizing microbial populations also varied among ecosystems and were 5 to 12 times greater in sediment after chronic petrogenic chemical exposure than in sediment from an uncontaminated ecosystem. Sediment from an ecosystem exposed to agricultural chemicals had a mineralization half-life of 3.2 weeks for naphthalene and showed about a 30-fold increase in heterotrophic bacterial populations in comparison to uncontaminated sediments, but only a 2- to 3-fold increase in hydrocarbon-degrading bacteria. Analysis of organic solvent-extractable residues from the microcosms by high-pressure liquid chromatography detected polar metabolites which accounted for 1 to 3% of the total radioactivity. Purification of these residues by thin-layer chromatography and further analysis by gas chromatography-mass spectrometry indicated that cis-1,2-dihydroxy-1,2-dihydronaphthalene, 1-naphthol, salicylic acid, and catechol were metabolites of naphthalene. These results provide useful estimates for the rates of naphthalene mineralization in different natural ecosystems and on the degradative pathway for microbial metabolism of naphthalene in freshwater and estuarine environments.

Biodegradation, Environmental↗
PubMed2003

Environmental persistence of chemicals and their carcinogenic risks to humans.

A "chemical population"-based investigation of xenobiotics (i.e. a sample of 10,000 chemicals representative of agents in commerce, industry, and the environment, both synthetic and natural) that have the potential for ecotoxicity because of their persistence in the environment and their potential association with carcinogenic risks to humans was undertaken. The analyses revealed a statistically significant association between resistance to environmental biodegradation and the prevalence of chemical with the potential to induce systemic toxicity and cancer. On the other hand, there was no association between biopersistence and the potential for inducing toxicities unrelated to carcinogenesis, e.g. allergic contact dermatitis in humans and sensory irritation in mice.

Biodegradation, Environmental↗
PubMed2002

Mechanism of aerobic transformation of carbon tetrachloride by poplar cells.

The biochemical mechanism of carbon tetrachloride transformation by poplar cells was investigated using an axenic poplar cell culture. After one-day incubations of poplar cells under aerobic conditions, about 1.5% of dosed carbon tetrachloride was transformed to carbon dioxide, about 0.001% to chloroform and about 3% of the carbon was bound to insoluble poplar cellular materials. The production of carbon dioxide increased under aerobic conditions while the formation of chloroform and cell binding of carbon tetrachloride-carbon was enhanced under anaerobic conditions. Both carbon dioxide production and cell binding were significantly inhibited by a general inhibitor of cytochrome P-450 activity (carbon monoxide) and by specific P-450 2E1 inhibitors (chlorzoxazone, isoniazid, 4-methylpyrazole and 1-phenylimidazole). However, no inhibitory effects were observed when the cells were incubated in the presence of lignin peroxidase inhibitors (NaVO3 and 3-amino-1,2,4-triazole). These results suggest that an enzyme similar to mammalian cytochrome P450-2E1 is involved in the metabolism of carbon tetrachloride by poplar cells. This study demonstrates an environmental biodegradative process for carbon tetrachloride that operates under aerobic conditions.

Aerobiosis↗
PubMedDate not supplied

Phenylmercuric acetate biodegradation by environmental strains of Pseudomonas species.

Organomercurial pollution occurring in the Rhine river in 1986 led us to study the possibility of depollution by mercury-resistant environmental aquatic strains. Four species of Pseudomonas were investigated for their ability to biotransform phenylmercuric acetate (PMA). Such biological depollution was demonstrated to be due to an enzymatic activity in whole cells and in cell-free extracts from Pseudomonas fluorescens and other Pseudomonas species. PMA biotransformation was followed by high-performance liquid chromatography. Some of those bacteria growing between 4 and 41 degrees C probably represent a natural means of organomercurial depollution, which acts slowly in interaction with other organisms and non-organic porous surfaces.

Biodegradation, Environmental↗
PubMed1999

Earthworm egg capsules as vectors for the environmental introduction of biodegradative bacteria.

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.

2,4-Dichlorophenoxyacetic Acid↗
PubMed2003

Effects of carbon substrate enrichment and DOC concentration on biodegradation of PAHs in soil.

AIMS: Two common reasons to explain slow environmental biodegradation of polycyclic aromatic hydrocarbons (PAHs), namely lack of appropriate carbon sources for microbial growth and limited bioavailability of PAHs, were tested in a laboratory bioassay using a creosote-contaminated soil. METHODS AND RESULTS: The soil, containing a total of 8 mg g-1 of 16 PAHs, was sieved and incubated in bottles for 45 days. The first explanation was tested by enrichment with the analogue anthracene and the non-analogue myristic acid, and both failed to stimulate degradation of all PAHs except anthracene. The second explanation was tested by addition of different concentrations of dissolved organic carbon (DOC), with effects depending on the DOC concentration and the molecular size of the PAH. The degradation was enhanced from 10 to 35% for 12 PAHs when the soil was saturated. The degraded amounts of individual PAHs were proportional to their concentration in the soil. CONCLUSIONS: The slow in situ degradation of PAHs was enhanced by more than three times by adding water as a solvent. Addition of DOC facilitated the degradation of four- to six-ring PAHs. SIGNIFICANCE AND IMPACT OF STUDY: Bioremediation of PAH-contaminated sites may be facilitated by creating water-saturated conditions but retarded by addition of other carbon substrates, such as analogue compounds.

Biodegradation, Environmental↗
PubMed2005

[Environmental stimuli-sensitive biodegradable drug delivery systems].

Environmental stimuli-sensitive biodegradable drug delivery systems are drawing more and more attentions because of their advantages such as smart properties, high efficiency and easy-to-handle properties. On the basis of a large quantity of references on this topic, a review has been made on the developments of the thermosensitive and pH-sensitive intelligent polymeric systems for drug delivery.

Biocompatible Materials↗
PubMed1993

Toxicological assessment of biodegraded pentachlorophenol: Microtox and fish embryos.

A Gram-negative bacterium, Pseudomonas sp. strain SR3, was isolated from soil at a former wood treatment plant in north central Florida. The ability of this bacterium to degrade pentachlorophenol (PCP) was confirmed by growing cells in a basal salts medium in which PCP was the only source of carbon and energy. Degradation from a measured concentration of 39-40 micrograms PCP/ml to 0.0006 micrograms PCP/ml was observed within 120 h of incubation in the presence of PCP-induced cells of Pseudomonas sp. strain SR3. The initial cell density in these cultures was 6 x 10(6) cfu/ml. Microtox 5 min EC50 toxicity tests revealed that aqueous solutions of PCP, measured concentrations 39-40 micrograms/ml were toxic but that final biodegraded samples, 0.0006 micrograms PCP/ml were nontoxic. However, bioassays with embryonic inland silversides, Menidia beryllina, showed that the biodegraded samples were embryotoxic or teratogenic. Water containing added PCP at concentrations up to 30 times higher than measured in the final biodegraded samples was less toxic/teratogenic. These results indicate that while biodegradation of PCP was nearly complete, intermediate metabolites of the degradation process or undegraded impurities in PCP were toxic or teratogenic. Thus, the M. beryllina bioassay allows extremely sensitive assessment of toxicity associated with biodegraded environmental pollutants and may be a useful criterion for determining whether bioremediated water or soil is safe for discharge back into the environment.

Abnormalities, Drug-Induced↗
PubMed2005

Biodegradation characteristics of environmental endocrine disruptor di-n-butyl phthalate.

OBJECTIVE: The biodegradation characteristics of di-n-butyl phthalate (DBP), an environmental endocrine disruptor, were studied by the method of dominant bacteria and immobilized microorganisms. METHODS: Taking DBP as the only carbon source to acclimatize the collected activated sludge, the concentration of DBP increased progressively in the process of acclimatization. Plate streaking was used to separate 1 strain of the degradation dominant bacteria after acclimatization. Better conditions to degrade DBP by the bacterium could be obtained through orthogonal experiments and the bacterium was identified. Then the acclimated activated sludge was made to immobilize the microorganism using polyvinyl alcohol as entrapment agent. The immobilized microorganism degraded DBP at different conditions. RESULTS: The appropriate conditions to degrade DBP by the dominant bacteria were: degradation time, 32 h; DBP concentration, 200 mg/L; rate of shaking incubator, 100 r/min; pH, 7 and temperature, 30 degrees C. DBP could be degraded by more than 95% under such conditions. The bacteria were identified as Pseudomonas. The proliferated immobilized microorganisms degraded DBP more effectively and more adapted to temperature and pH than the free acclimated activated sludge. CONCLUSION: One strain of DBP degradation dominant bacteria was separated from the acclimatized activated sludge. It could grow with DBP as the only carbon source and energy, and degraded DBP effectively. After having been immobilized and proliferated, the dominant bacteria could keep a higher biological activity and degrade DBP more effectively than activated sludge.

Biodegradation, Environmental↗
PubMed2006

Characterisation of biodegradation capacities of environmental microflorae for diesel oil by comprehensive two-dimensional gas chromatography.

In contaminated soils, efficiency of natural attenuation or engineered bioremediation largely depends on biodegradation capacities of the local microflorae. In the present study, the biodegradation capacities of various microflorae towards diesel oil were determined in laboratory conditions. Microflorae were collected from 9 contaminated and 10 uncontaminated soil samples and were compared to urban wastewater activated sludge. The recalcitrance of hydrocarbons in tests was characterised using both gas chromatography (GC) and comprehensive two-dimensional gas chromatography (GCxGC). The microflorae from contaminated soils were found to exhibit higher degradation capacities than those from uncontaminated soil and activated sludge. In cultures inoculated by contaminated-soil microflorae, 80% of diesel oil on an average was consumed over 4-week incubation compared to only 64% in uncontaminated soil and 60% in activated sludge cultures. As shown by GC, n-alkanes of diesel oil were totally utilised by each microflora but differentiated degradation extents were observed for cyclic and branched hydrocarbons. The enhanced degradation capacities of impacted-soil microflorae resulted probably from an adaptation to the hydrocarbon contaminants but a similar adaptation was noted in uncontaminated soils when conifer trees might have released natural hydrocarbons. GCxGC showed that a contaminated-soil microflora removed all aromatics and all branched alkanes containing less than C(15). The most recalcitrant compounds were the branched and cyclic alkanes with 15-23 atoms of carbon.

Alkanes↗
PubMed1981

Use of a fractional factorial design to evaluate interactions of environmental factors affecting biodegradation rates.

For investigation of main and interactive effects of six experimentally controlled environmental factors on phenol biodegradation in a shake-flask system, a largely neglected statistical procedure was applied. A major benefit resulting from the application of the orthogonal, fractional factorial design is that the number of experiments necessary to evaluate multifactor interactions is limited. In our investigation, the required number of experiments was reduced to 81 from the 324 necessary with conventional factorial designs; information was sacrificed for only 3 of 15 possible two-factor interactions. Six experimentally controlled factors were investigated at two or three treatment levels each; the six factors were (1) amount of phenol substrate, (2) amount of bacterial inoculum, (3) filtration of inoculum, (4) type of basal salts medium, (5) initial pH of basal salts medium, and (6) flask closure. Significant main effects were found for factors 1, 2, and 4; whereas significant interactive effects were found only for factor 2 with factor 3 and for factor 2 with factor 5. Our results suggest that the application of these statistical designs will greatly reduce the number of experiments necessary to evaluate multifactor effects on degradation rates during optimization of both hazard screening systems and waste treatment systems.

Journal Article↗
PubMed2006

Insecticidal, antifeedant and oviposition deterrent effects of the essential oil and individual compounds from leaves of Chloroxylon swietenia DC.

Essential oil from the leaves of Chloroxylon swietenia DC. was obtained by hydrodistillation and cold extraction, and the chemical composition was determined by gas chromatography and gas chromatography-mass spectrometry. The major identified components were limonene, geijerene, pregeijerene, germacrene D and trans-beta-ocimene. Laboratory bioassays of the essential oil and four constituents of essential oil isolates were evaluated for insecticidal, antifeedant and oviposition deterrent effects on tobacco cutworm, Spodoptera litura (F.). Toxicity was determined by topical application of the isolates at varying concentrations. Pure oil, geijerene and pregeijerene were found to be more toxic, with LD50 values of 28.6, 35.4 and 40.7 microg per larva respectively. Maximum feeding deterrence was noted for geijerene and pregeijerene, with DC(50) values of 82.5 and 95.1 microg cm(-2) respectively. Furthermore, pure oil, geijerene and pregeijerene displayed oviposition deterrence, even at low concentrations. These results indicate that these natural products may lead to useful, biodegradable, environmentally safe insect control agents.

Animals↗
PubMedDate not supplied

Microbial degradation of poly(amino acid)s.

Natural poly(amino acid)s are a group of poly(ionic) molecules (ionomers) with various biological functions and putative technical applications and play, therefore, an important role both in nature and in human life. Because of their biocompatibility and their synthesis from renewable resources, poly(amino acid)s may be employed for many different purposes covering a broad spectrum of medical, pharmaceutical, and personal care applications as well as the domains of agriculture and of environmental applications. Biodegradability is one important advantage of naturally occurring poly(amino acid)s over many synthetic polymers. The intention of this review is to give an overview about the enzyme systems catalyzing the initial steps in poly(amino acid) degradation. The focus is on the naturally occurring poly(amino acid)s cyanophycin, poly(epsilon-L-lysine) and poly(gamma-glutamic acid); but biodegradation of structurally related synthetic polyamides such as poly(aspartic acid) and nylons, which are known from various technical applications, is also included.

Amino Acids↗