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Margaret E. Elmes MB BS PhD J. Clarkson PhD J. Gwyn Jones PhD 《Environmental geochemistry and health》1983,5(2-3):85-87
The zinc content of intestinal epithelial cells in human jejunum and ileum has been measured using X-ray microanalysis. The range of values was wide, the highest being found in stem cells and enterocytes. Significant differences were found in jejunum from gastric carcinoma patients and ileum from Crohn's disease patients compared with patients with non malignant, non inflammatory disease. 相似文献
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Vivas A Vörös I Biró B Campos E Barea JM Azcón R 《Environmental pollution (Barking, Essex : 1987)》2003,126(2):179-189
The effect of inoculation with indigenous naturally occurring microorganisms (an arbuscular mycorrhizal (AM) fungus and rhizosphere bacteria) isolated from a Cd polluted soil was assayed on Trifolium repens growing in soil contaminated with a range of Cd. One of the bacterial isolate showed a marked PGPR effect and was identified as a Brevibacillus sp. Mycorrhizal colonization also enhanced Trifolium growth and N, P, Zn and Ni content and the dually inoculated (AM fungus plus Brevibacillus sp.) plants achieved further growth and nutrition and less Cd concentration, particularly at the highest Cd level. Increasing Cd level in the soil decreased Zn and Pb shoot accumulation. Coinoculation of Brevibacillus sp. and AM fungus increased shoot biomass over single mycorrhizal plants by 18% (at 13.6 mg Cd kg(-1)), 26% (at 33.0 mg Cd kg(-1)) and 35% (at 85.1 mg Cd (kg(1)). In contrast, Cd transfer from soil to plants was substantially reduced and at the highest Cd level Brevibacillus sp. lowered this value by 37.5% in AM plants. Increasing Cd level highly reduced plant mycorrhization and nodulation. Strong positive effect of the bacterium on inocula, are important in plant Cd tolerance and development in Cd polluted soils. 相似文献
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Moreno B Vivas A Nogales R Macci C Masciandaro G Benitez E 《Environmental science and pollution research international》2009,16(3):253-264
Background, aim, and scope In this work, the potential for using olive-mill solid waste as an organic amendment for biochemical and biological restoration
of a trichloroethylene-contaminated soil, which has previously been stabilized through vermicomposting processes, has been
explored.
Materials and methods Trichloroethylene-contaminated water was pumped into soil columns with a layer of vermicompost at 10-cm depth (biobarrier
system). The impacts of the trichloroethylene on the microbial community were evaluated by determining: (1) the overall microbial
activity (estimated as dehydrogenase activity) and enzyme activities related to the main nutrient cycles (β-glucosidase, o-diphenoloxidase, phosphatase, urease, and arylsulphatase activities). In addition, isoelectric focusing of the soil extracellular
humic-β-glucosidase complexes was performed to study the enzymatically active humic matter related to the soil carbon cycle.
(2) The soil bacterial diversity and the molecular mechanisms for the bacterial resistance to organic solvents were also determined.
For this, polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) was used to detect changes in bacterial
community structure and PCR-single-strand conformational polymorphism (SSCP) was developed and optimised for detection and
discrimination of the resistance-nodulation-division (RND) genes amplified from the contaminated soils.
Results Vermicompost reduced, with respect to the unamended soil, about 30% of the trichloroethylene leaching during the first month
of the experiment. Trichloroethylene had a marked negative effect on soil dehydrogenase, β-glucosidase, urease, phosphatase,
and arylsulphatase activities. Nevertheless, the vermicompost tended to avoid this toxic effect. Vermicompost also displays
stable humic-β-glucosidase complexes that increased the extracellular activity related to C-cycle in the contaminated soils.
The isoelectric focusing technique showed a more biochemically active humic matter in the soil sampled under the vermicompost.
The behaviour of the three main phyla of bacteria isolated from the DGGE bands was quite different. Bands corresponding to
Actinobacteria disappeared, whereas those affiliated with Proteobacteria remained after the trichloroethylene contamination. The disappeared Actinobacteria became visible in the soil amended with the vermicompost. Bands corresponding to Bacteriodetes appeared only in columns of contaminated soils. In this study, six types of RND proteins were detected by PCR-SSCP in the
natural soil, three in the trichloroethylene-contaminated soil and 7/5 in trichloroethylene-contaminated soil above/below
the vermicompost in the biobarrier columns. Trichloroethylene tended to reduce or eliminate all the clones detected in the
uncontaminated soil, whereas new efflux pumps appeared in the biobarrier columns.
Discussion Although enzymes incorporated into the humic substances of vermicomposted olive wastes are quite stable, trichloroethylene
also inhibited the background levels of the soil extracellular β-glucosidase activity in the amended soils. The decrease was
less severe in the biobarrier system, but in any case, no relation was found between the levels of trichloroethylene in soil
and extracellular β-glucosidase activity, or between the latter and the quantity of humic carbon in soils. The isoelectric
focusing technique was carried out in the humic fraction to determine whether the loss of activity occurred in overall extracellular
β-glucosidase or in that linked to stable humic substances (humic–enzyme complexes). The contaminated soils showed the lower
enzyme activities, whereas contaminated and amended soils presented greater quantity of focalised (and therefore stable) humic
carbon and spectra heterogeneity: very different bands with higher enzyme activities. No clear relationship between trichloroethylene
concentration in soil and diversity of the bacterial population was noted. Similar patterns could be found when the community
structures of bacteria and microbial activity were considered. Since the use of the dehydrogenase assay has been recognised
as a useful indicator of the overall measure of the intensity of microbial metabolism, these results could be attributed to
PCR-DGGE methodology, since the method reveals the presence of dominant populations regardless of their metabolic state. Trichloroethylene
maintained or even increased the number of clones with the DNA encoding for RND proteins, except for the contaminated soil
located above the vermicompost. However, the main effect of trichloroethylene was to modify the structure of the community
in contaminated soils, considering the type of efflux pumps encoded by the DNA extracted from soil bacteria.
Conclusions Trichloroethylene inhibited specific functions in soil and had a clear influence on the structure of the autochthonous bacterial
community. The organic matter released by the vermicomposted olive waste tended to avoid the toxic effect of the contaminant.
Trichloroethylene also inhibited the background levels of the soil extracellular β-glucosidase activity, even when vermicompost
was present. In this case, the effect of the vermicompost was to provide and/or to stimulate the humic-β-glucosidase complexes
located in the soil humic fraction >104, increasing the resistance of the enzyme to the inhibition. The bacterial community from the soil presented significantly
different mechanisms to resistance to solvents (RND proteins) under trichloroethylene conditions. The effect of the vermicompost
was to induce these mechanisms in the autochthonous bacterial community and/or incorporated new bacterial species, able to
grow in a trichloroethylene-contaminated ambient. Coupled biochemical and molecular methodologies are therefore helpful approaches
in assessing the effect of an organic amendment on the biochemical and biological restoration of a trichloroethylene-contaminated
soil.
Recommendations and perspectives Since the main biochemical and biological effects of the organic amendment on the contaminated soil seem to be the incorporation
of biochemically active humic matter, as well as new bacterial species able to grow in a trichloroethylene-contaminated ambient,
isoelectric focusing and PCR-SSCP methodologies should be considered as parts of an integrated approach to determine the success
of a restoration scheme. 相似文献
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Vivas A Moreno B del Val C Macci C Masciandaro G Benitez E 《Journal of environmental monitoring : JEM》2008,10(11):1287-1296
The aim of this study was to characterize soils contaminated by different levels of heavy metals and hydrocarbons (Madonna Dell'Acqua, Pisa, Italy). The soils were chemically and biochemically analysed by measuring the standard chemical properties and some enzyme activities related to microbial activity (dehydrogenase activity) and the soil carbon cycle (total and extracellular beta-glucosidase activities). The metabolic capacities of soil microorganisms to degrade hydrocarbons through catechol 2,3-dioxygenase were also described. The microbial diversity of contaminated and uncontaminated soils was estimated by denaturing gradient gel electrophoresis (DGGE) of amplified 16S rDNA sequences. The PCR/single-strand conformation polymorphism (PCR/SSCP) method was used to estimate the genetic diversity of PAH-degrading genes in both contaminated and uncontaminated soils. A greater bacterial diversity and lower catechol 2,3-dioxygenase activity was detected in unpolluted soils. The complexity of the microbial community (Shannon and Simpson indices) as well as the dehydrogenase soil activity negatively correlated with contamination levels. The greatest PAH-degrading gene diversity and the most intense catechol 2,3-dioxygenase activity were found in the soils with the highest levels of hydrocarbons. Heavy metals and hydrocarbon pollution has caused a genetic and metabolic alteration in microbial communities, corresponding to a reduction in microbial activity. A multi-technique approach combining traditional biochemical methods with molecular-based techniques, along with some methodological improvements, may represent an important tool to expand our knowledge of the role of microbial diversity in contaminated soil. 相似文献
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The interaction between two autochthonous microorganisms (Brevibacillus brevis and Glomus mosseae) isolated from Cd amended soil increased plant growth, arbuscular mycorrhizal (AM) colonization and physiological characteristics of the AM infection (measured as SDH or ALP activities). The enhanced plant Cd tolerance after coinoculation with native microorganisms seemed to be a consequence of increased P and K acquisition and, simultaneously, of decreased concentration of Cd, Cr, Mn, Cu, Mo, Fe and Ni in plant tissue. Autochthonous microbial strains were more efficient for nutrient uptake, to immobilize metals and decrease their translocation to the shoot than reference G. mosseae (with or without bacteria). Indole acetic acid produced by B. brevis may be related to its ability for improving root growth, nodule production and AM fungal intra and extraradical development. Dehydrogenase, phosphatase and beta-glucosidase activities, indicative of microbial metabolism and soil fertility, were maximized by the coinoculation of autochthonous microorganisms in cadmium polluted conditions. As a consequence, the use of native microorganisms may result very efficient in bioremediation. 相似文献
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Twenty populatios of Littorina angulifera, inhabiting islands composed of the mangrove tree Rhizophora mangle, were assayed at an esterase locus to determine whether genetic differentiation was associated with distance between populations. It was predicted, on the basis of larval dispersal in this species, that genetic differentiation between populations on islands separated by long distances should be greater than those on islands located near each other. A chi0square test of homogeneity revealed significant differences in esterase gene frequencies among the 20 island populations. However, there was no association of distance between islands and genetic heterogeneity. In addition, a cline in gene frequency was found to be assiciated with latitude. Factors responsible for the observed pattern of heterogeneity at the esterase locus are discussed. 相似文献
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Two bacterial strains isolated from a Zn-polluted soil enhance plant growth and mycorrhizal efficiency under Zn-toxicity 总被引:1,自引:0,他引:1
In this study we investigated the interactions among plant, rhizosphere microorganisms and Zn pollution. We tested the influence of two bacterial strains isolated from a Zn-polluted soil on plant growth and on the symbiotic efficiency of native arbuscular mycorrhizal fungi (AMF) under Zn toxicity. The two bacterial strains exhibited Zn tolerance when cultivated under increasing Zn levels in the medium. However, strain B-I showed a higher Zn tolerance than strain B-II at the two highest Zn levels in the medium (75 and 100 mg l(-1) Zn). Molecular identification placed the strain B-I within the genus Brevibacillus. Our results showed that bacterial strain B-I consistently enhanced plant growth, N and P accumulation, as well as nodule number and mycorrhizal infection which demonstrated its plant-growth promoting (PGP) activity. This strain B-I has been shown to produce IAA (3.95 microg ml) and to accumulate 5.6% of Zn from the growing medium. The enhanced growth and nutrition of plants dually inoculated with the AMF and bacterium B-I was observed at three Zn levels assayed. This effect can be related to the stimulation of symbiotic structures (nodules and AMF colonization) and a decreased Zn concentration in plant tissues. The amount of Zn acquired per root weight unit was reduced by each one of these bacterial strains or AMF and particularly by the mixed bacterium-AMF inocula. These mechanisms explain the alleviation of Zn toxicity by selected microorganisms and indicate that metal-adapted bacteria and AMF play a key role enhancing plant growth under soil Zn contamination. 相似文献
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