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At least 829 records · Page 46Linked to original sources
PubMed2000

Prediction of in vivo metabolic clearance of 25 different petroleum hydrocarbons by a rat liver head-space technique.

In vitro rates of metabolism and Michaelis-Menten constants were determined for 25 different C6 to C10 hydrocarbons using rat liver slices in a vial head-space equilibration system. The rates of metabolism were compared with steady-state levels obtained in vivo in the same strains of rats after inhalation. Aromates were metabolized at a higher rate than naphthenes n-alkanes, isoalkanes and 1-alkenes. The aromates showed, in contrast to the other hydrocarbons investigated, increased metabolism with increasing number of carbon atoms up to C8 (o-xylene, the most extensively metabolized compound). The in vivo steady-state concentrations of the aromates in blood were inversely related to the in vitro efficiency of their metabolism. This explains the pattern of blood levels observed for the C6 to C10 aromates in the rat after inhalation, with o-xylene demonstrating the lowest concentration. In general, the extent of tissue metabolism of the investigated hydrocarbons might be of greater importance for their body distribution than their lipophilicity, especially for the highly metabolized compounds. The high in vitro intrinsic liver clearances found for the aromates indicate a flow-dependent metabolism of these hydrocarbons in vivo. The head-space liver slice equilibration system seems to work adequately for metabolic studies of hydrocarbons with different volatility and water solubility.

Animals↗
PubMed2003

Health of flatfish from localities in Placentia Bay, Newfoundland, contaminated with petroleum and PCBs.

This study compared the health of flatfish inhabiting two areas in Placentia Bay, Newfoundland, contaminated either with polycyclic aromatic hydrocarbons (PAHs) or polychlorinated biphenyls (PCBs) with samples from reference sites. Initially, four species of flatfish, including American plaice (Hippoglossoides platessoides), yellowtail flounder (Limanda ferruginea), gray sole (Glyptocephalus cynoglossus), and winter flounder (Pleuronectes americanus), were sampled only for external lesions from commercial catches at three offshore sites. Others, captured by scuba divers at inshore sites, were autopsied to compare external lesions, condition (K) factor, hepatosomatic index (HSI), hemoglobin and lymphocyte levels, histological changes in the liver and spleen, and two parasites, metacercariae of Cryptocotyle lingua in the skin and a digenetic trematode, Steringophorus furciger, in the digestive tract. A higher prevalence of lesions occurred in the four species of flatfish caught offshore by commercial fisherman near the oil terminal and the PCB-contaminated dockyard than at a reference site. Lesions were also more prevalent in three species of flatfish captured by scuba divers inshore near the oil terminal and were associated with significantly lower K factor and lymphocyte levels but elevated HSI values and histopathological changes in the liver and spleen than in reference samples. Winter flounder sampled at two locations near the PCB-contaminated dockyard and a PAH-polluted small boat wharf also exhibited more external lesions, liver discoloration, and lower K factor, hemoglobin, and lymphocyte but higher HSI values and hepatic and splenic hemosiderosis than in reference fish. Prevalence of C. lingua in the skin was significantly greater but S. furciger in the digestive tract lower in samples taken from the aforementioned contaminated sites than from the reference locations. These results, based on several bioindicators, suggest that the health of bottom-dwelling flatfish at three sites of this embayment was impaired by chronic exposure to sediment contaminated with PAHs or PCBs.

Animals↗
PubMed2006

Microbial community analysis of soils contaminated with lead, chromium and petroleum hydrocarbons.

The impact on the microbial community of long-term environmental exposure to metal and organic contamination was investigated. Twenty-four soil samples were collected along a transect dug in soils contaminated with road paint and paint solvents, mainly toluene. Chemical analysis along the transect revealed a range from high to low concentrations of metals (lead and chromium) and organic solvent compounds. Principal components analysis of microbial community structure based on denaturing gradient gel electrophoresis of the V3 region of the 16S rRNA gene and fatty acid methyl esters derived from phospholipids (phospholipid fatty acid analysis) showing samples with similar fingerprints also had similar contaminant concentrations. There was also a weak positive correlation between microbial biomass and the organic carbon concentration. Results indicated that microbial populations are present despite some extreme contaminant levels in this mixed-waste contaminated site. Nucleotide sequence determination of the 16S rRNA gene indicated the presence of phylogenetically diverse bacteria belonging to the alpha-, beta-, gamma-, and delta-Proteobacteria, the high and low G + C Gram-positive bacteria, green nonsulfur, OP8, and others that did not group within a described division. This indicates that soils contaminated with both heavy metals and hydrocarbons for several decades have undergone changes in community composition, but still contain a phylogenetically diverse group of bacteria (including novel phylotypes) that warrant further investigation.

Bacteria↗
PubMed1997

Petroleum hydrocarbon bioremediation: sampling and analytical techniques, in situ treatments and commercial microorganisms currently used.

The sampling and analytical methods, along with available microorganisms, used for in situ hydrocarbon bioremediation are reviewed. Each treatment method is briefly described and its advantages and limitations pertaining to potential applications are evaluated. Bioremediation provides cost-effective, contaminant- and substrate-specific treatments equally successful in reducing the concentrations of single compounds or mixtures of biodegradable materials. In situ treatments rarely yield undesirable byproducts, but precautions and preliminary baseline tests are always recommended. Sampling methods should adhere to good laboratory and field practices and usually do not require highly trained personnel. Analytical methods vary in sensitivity, cost, duration of sample analysis and personnel training required. Voucher specimens of bacterial strains used in bioremediation exist in various repositories (e.g. ATCC, DSM, etc.) or are commercially available, and are usually covered by patent rights. Each one of these strains may yield spectacular results in vitro for specific target compounds. However, the overall success of such strains in treating a wide range of contaminants in situ remains limited. The reintroduction of indigenous microorganisms isolated from the contaminated site after culturing seems to be a highly effective bioremediation method, especially when microorganism growth is supplemented by oxygen and fertilizers.

Bacteria↗
PubMed2005

Potential of preliminary test methods to predict biodegradation performance of petroleum hydrocarbons in soil.

Preliminary tests at different scales such as degradation experiments (laboratory) in shaking flasks, soil columns and lysimeters as well as in situ respiration tests (field) were performed with soil from two hydrocarbon contaminated sites. Tests have been evaluated in terms of their potential to provide information on feasibility, degradation rates and residual concentration of bioremediation in the vadose zone. Sample size, costs and duration increased with experimental scale in the order shaking flasks - soil columns - lysimeter - in situ respiration tests, only time demand of respiration tests was relatively low. First-order rate constants observed in degradation experiments exhibited significant differences between both, different experimental sizes and different soils. Rates were in line with type and history of contamination at the sites, but somewhat overestimated field rates particularly in small scale experiments. All laboratory experiments allowed an estimation of residual concentrations after remediation. In situ respiration tests were found to be an appropriate pre-testing and monitoring tool for bioventing although residual concentrations cannot be predicted from in situ respiration tests. Moreover, this method does not account for potential limitations that might hamper biodegradation in the longer term but only reflects the actual degradation potential when the test is performed.

Aerobiosis↗
PubMed2006

Biodegradation of petroleum hydrocarbons in seawater at low temperatures (0-5 degrees C) and bacterial communities associated with degradation.

In this study biodegradation of hydrocarbons in thin oil films was investigated in seawater at low temperatures, 0 and 5 degrees C. Heterotrophic (HM) or oil-degrading (ODM) microorganisms enriched at the two temperatures showed 16S rRNA sequence similarities to several bacteria of Arctic or Antarctic origin. Biodegradation experiments were conducted with a crude mineral oil immobilized as thin films on hydrophobic Fluortex adsorbents in nutrient-enriched or sterile seawater. Chemical and respirometric analysis of hydrocarbon depletion showed that naphthalene and other small aromatic hydrocarbons (HCs) were primarily biodegraded after dissolution to the water phase, while biodegradation of larger polyaromatic hydrocarbons (PAH) and C(10)-C(36) n-alkanes, including n-hexadecane, was associated primarily with the oil films. Biodegradation of PAH and n-alkanes was significant at both 0 and 5 degrees C, but was decreased for several compounds at the lower temperature. n-Hexadecane biodegradation at the two temperatures was comparable at the end of the experiments, but was delayed at 0 degree C. Investigations of bacterial communities in seawater and on adsorbents by PCR amplification of 16S rRNA gene fragments and DGGE analysis indicated that predominant bacteria in the seawater gradually adhered to the oil-coated adsorbents during biodegradation at both temperatures. Sequence analysis of most DGGE bands aligned to members of the phyla Proteobacteria (Gammaproteobacteria) or Bacteroidetes. Most sequences from experiments at 0 degree C revealed affiliations to members of Arctic or Antarctic consortia, while no such homology was detected for sequences from degradation experiment run at 5 degrees C. In conclusion, marine microbial communities from cold seawater have potentials for oil film HC degradation at temperatures < or =5 degrees C, and psychrotrophic or psychrophilic bacteria may play an important role during oil HC biodegradation in seawater close to freezing point.

Arctic Regions↗
PubMed2005

Population dynamics of cotton rats (Sigmodon hispidus) inhabiting abandoned petroleum landfarms in Oklahoma, USA.

Previous work by our group has shown bioaccumulation of contaminants and alterations in the immune system of hispid cotton rats (Sigmodon hispidus) inhabiting petrochemical waste sites (landfarms). We studied populations of cotton rats inhabiting petrochemical landfarms or uncontaminated reference sites. Cotton rat populations inhabiting abandoned landfarms experienced reduced summer population densities and lower mean monthly survival, with maximum densities 65% that of populations inhabiting non-contaminated grassland (reference) sites. Survival was lower in populations from landfarms (0.62+/-0.04) compared to reference sites (0.75+/-0.04), with differences most notable during summer months. Cotton rat populations sampled from landfarms had even sex ratios and a lower proportion of juveniles compared to populations from reference sites. No differences were observed in the weight of epididymides, testes, uteri, or ovaries, and no differences in fecundity were detected among sites.

Animals↗
PubMed2005

Changes in phosphatidylcholine molecular species in the shrimp Macrobrachium borellii in response to a water-soluble fraction of petroleum.

The effect of the water-soluble fraction (WSF) of crude oil on lipid contents, lipid classes, FA, and PC molecular species was studied in high-phospholipid (hepatopancreas) and low-phospholipid (egg) tissues of a freshwater crustacean. After a 21-d exposure to a sublethal concentration of WSF, a significant decrease in shrimp total lipids was observed, although no alterations could be detected in the hepatopancreas or egg lipid contents. TAG/phospholipid ratios increased in the hepatopancreas and decreased in the eggs, suggesting alterations either in the mobilization of TAG to phospholipid pools or in the energy balance. The FA composition of phosphoglycerides in the hepatopancreas and eggs was dominated by PUFA, whereas the n-3/n-6 ratio was not affected by WSF exposure, although there was a significant increase in hepatopancreas 18:1n-9. Analysis of the PC molecular species by HPLC-ELSD showed the presence of 15 species, with 16:0/18:1, 18:1/18:2, 16:0/20:5, and 16:1/20:5 being the major species in the hepatopancreas. The PC molecular species in the eggs showed a different pattern, dominated by 16:0/18:1 and 18:1/18:2. Of the PC molecular species, 10 contained 22:6n-3, 20:5n-3, and 20:4n-6. Small amounts of di-PUFA species were also found. Exposure to WSF altered the PC molecular species in both tissues. The four major hepatopancreas molecular species and most of the ones containing PUFA decreased. This was compensated for by an increase in 16:1/18:1 (152%) and 18:1/18:1 (50%). The two major egg PC molecular species decreased, whereas the PUFA-containing ones increased. The contrasting responses of both tissues to WSF contamination suggests the presence of different homeostatic mechanisms.

Animals↗