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1.
Soil samples from an agricultural field contaminated with 10 ppm 14C-benz( a)anthracene in glass tubes were brought into contact with cultures of wood-rotting fungi, precultivated on wheat straw substrate.
Forty-five strains of white-rot fungi and four brown-rot fungi were tested for their ability to colonize the soil and to mineralize 14C-benz( a)anthracene to 14CO 2 within a 20-week incubation time. Twenty-two white-rot fungi and all brown-rot fungi were unable to colonize the soil. Twenty-three
strains of white-rot fungi, all belonging to the genus Pleurotus, colonized the soil. During the experiment the noncolonizing fungi and their substrate disintegrated more and more to a nonstructured
pulp from which water diffused into the soil. The same phenomenon was observed in the control which contained only straw without
fungus and contaminated soil. In samples with colonizing fungi the substrate as well as the mycelia in the soil remained visibly
unchanged during the entire experiment. Surprisingly, most samples with fungi not colonizing the soil and the control without
fungus liberated between 40 and 58 % of the applied radioactivity as 14CO 2 whereas the samples with the colonizing fungi respired only 15–25 % as 14CO 2. This was 3–5 times more 14CO 2 than that liberated from the control (4.9 %) which contained only contaminated soil without straw and fungus. A similar result
was obtained with selected colonizing and noncolonizing fungi and soil contaminated with 10 ppm 14C-pyrene. However, in pure culture studies in which 14C-pyrene was added to the straw substrate, Pleurotus sp. (P2), as a representative of the colonizing fungi, mineralized 40.3 % of the added radioactivity to 14CO 2. The noncolonizing fungi Dichomitus squalens and Flammulina velutipes liberated only 17.2 or 1.7 %, respectively, as 14CO 2. These results lead to the hypothesis that the native soil microflora stimulated by the formed products of straw lysis is
responsible for high degradation rates found with noncolonizing fungi. 相似文献
2.
The objectives of this work were to isolate the microorganisms responsible for a previously observed degradation of polycyclic
aromatic hydrocarbons (PAH) in soil and to test a method for cleaning a PAH-contaminated soil. An efficient PAH degrader was
isolated from an agricultural soil and designated as Mycobacterium LP1. In liquid culture, it degraded phenanthrene (58%), pyrene (24%), anthracene (21%) and benzo( a)pyrene (10%) present in mixture (initial concentration 50 μg ml −1 each) and phenanthrene (92%) and pyrene (94%) as sole carbon sources after 14 days of incubation at 30°C. In soil, Mycobacterium LP1 mineralised 14C-phenanthrene (45%) and 14C-pyrene (65%) after 10 days. The good ability of this Mycobacterium was combined with the benzo( a)pyrene oxidation effect obtained by 1% w/w rapeseed oil in a sequential treatment of a PAH-spiked soil (total PAH concentration
200 mg kg −1). The first step was incubation with the bacterium for 12 days and the second step was the addition of the rapeseed oil after
this time and a further incubation of 22 days. Phenanthrene (99%), pyrene (95%) and anthracene (99%) were mainly degraded
in the first 12 days and a total of 85% of benzo( a)pyrene was transformed during the whole process. The feasibility of the method is discussed. 相似文献
3.
Pleurotus sp. was grown in liquid medium and on a solid straw substrate, and activities of laccase and manganese-dependent peroxidase
(MnP) were recorded. The activities were the highest in a rich, glucose corn-steep liquid medium. In straw cultures, laccase
activity was about ten times lower. Under solid state conditions, MnP production was the highest during days 20–40, when laccase
activity already had declined. In straw cultures, mineralization of 14C-pyrene was measured as release of 14CO 2. The highest rates of pyrene mineralization occurred during days 20–45, i.e. the period of high MnP activities, suggesting a role of this enzyme in PAH degradation. Within 60d, 24% of pyrene was mineralized. 相似文献
4.
Nineteen filamentous fungi, isolated from estuarine sediments in Brazil, were screened for degradation of polycyclic aromatic hydrocarbons (PAH). The fungal isolates were incubated with pyrene. The cultures were extracted and metabolites in the extracts were detected by high performance liquid chromatography (HPLC) and u.v. spectral analyses. Six fungi were selected for further studies using [4,5,9,10- 14C]pyrene. Cyclothyrium sp., Penicillium simplicissimum, Psilocybe sp., and a sterile mycelium demonstrated the ability to transform pyrene. Cyclothyrium sp. was the most efficient fungus, transforming 48% of pyrene to pyrene trans-4,5-dihydrodiol, pyrene-1,6-quinone, pyrene-1,8-quinone and 1-hydroxypyrene. This fungus was also evaluated with a synthetic mixture of PAH. After 192 h of incubation, Cyclothyrium sp. was able to degrade simultaneously 70, 74, 59 and 38% of phenanthrene, pyrene, anthracene and benzo[a]pyrene, respectively. 相似文献
5.
The effect of soil microorganisms on mineralization of 14C-labelled pyrene by white-rot fungi in solid-state fermentation was investigated. Two strains of white-rot fungi, Dichomitus squalens and a Pleurotus sp., were tested. The fungi were incubated on milled wheat straw contaminated with [ 14C]pyrene for 15 weeks. CO 2 and 14CO 2 liberated from the cultures were determined weekly. To study the effect of soil microorganisms on respiration and [ 14C]pyrene mineralization in different periods of fungal development, the fungal substrate was covered with soil at different
times of incubation (after 0, 1, 3, 5, 7, 9 or 11 weeks). The two fungi showed contrasting ecological behaviour in competition
with the soil microflora. Pleurotus sp. was highly resistant to microbial attack and had the ability to penetrate the soil. D. squalens was less competitive and did not colonize the soil. The resistance of the fungus was dependent on the duration of fungal
preincubation. Mineralization of [ 14C]pyrene by mixed cultures of D. squalens and soil microorganisms was higher than by the fungus or the soil microflora alone when soil was added after 3 weeks of incubation
or later. With Pleurotus sp., the mineralization of [ 14C]pyrene was enhanced by the soil microflora irrespective of the time of soil application. With D. squalens, which in pure culture mineralized less [ 14C]pyrene than did Pleurotus sp., the increase of [ 14C]pyrene mineralization caused by soil application was higher than with Pleurotus sp.
Received: 8 March 1996 / Received revision: 1 July 1996 / Accepted: 8 July 1996 相似文献
6.
At present, there is little information on the optimization of the degradation of polycyclic aromatic hydrocarbons (PAH)
by deuteromycete filamentous fungi, a reaction catalyzed by cytochrome P450 monooxygenases. We utilized response-surface methodology to determine the optimal growth conditions for the oxidation
of the PAH pyrene by Penicillium janthinellum SFU403, with respect to the variables glucose concentration, nitrate concentration and bioconversion time. Models were derived
for the relationship between the variables tested and the level of the pyrene oxidation products, 1-pyrenol (1-PY) and pyrenequinones
(PQ). Production of 1-PY and PQ were optimized by the same glucose and nitrate concentrations: 2.5% glucose and 1.5% sodium
nitrate. The optimized 1-PY and PQ bioconversion times were 71 h and 73 h respectively. These conditions improved the yield
of 1-PY by fivefold and PQ were more than 100-fold higher than the baseline levels obtained in this study. The optimized PQ
yield represented 95% of the initial pyrene, thus the total optimised pyrene bioconversion to 1-PY and PQ was approximately
100%. Concentrations of glucose exceeding 4.0% repressed pyrene hydroxylation. Pyrene hydroxylation occurred almost exclusively
during the deceleration phase of culture growth.
Received: 20 July 1998 / Received revision: 7 December 1998 / Accepted: 10 January 1999 相似文献
7.
The ability of the white-rot fungus Phanerochaete chrysosporium (INA-12) to degrade various polynuclear aromatic hydrocarbons (PAH) was investigated. Under static, non-nitrogen-limiting conditions, P. chrysosporium mineralized both phenanthrene and benzo[ a]pyrene. Total mineralization, based on radioactive tracing, was limited to 1.8%–3% for phenanthrene and benzo[ a]pyrene respectively. In both cases the pattern of mineralization did not correlate temporally with the production of lignin peroxidase activity. Sorption of radiolabelled material to the biomass was very significant with 22% and 40% of the total radioactivity being sorbed for benzo[ a]pyrene and phenanthrene respectively. A number of models were examined to predict the sorption isotherms, the best performance being obtained with a three-parameter empirical model. It is apparent that lignin peroxidase is not necessarily involved in the biodegradation of all PAH and that a significant factor in PAH biodegradation and/or disappearance in cultures with the intact fungus may be attributed to sorption phenomena. 相似文献
8.
The degradation of eight unlabeled highly condensed polycyclic aromatic hydrocarbons (PAH) and the mineralization of three
14C-labeled PAH by the white-rot fungus Pleurotus sp. Florida was investigated. Three concentrations containing 50, 250 or 1250 μg each unlabeled PAH/5 g straw were added
to sterile sea sand. Selected treatments were added subsequently with 14C-labeled pyrene, benzo[ a]anthracene or benzo[ a]pyrene. The PAH-loaded sea sand was then mixed into straw substrate and incubated. The disappearance of the unlabeled four-to
six-ring PAH: pyrene, benzo[ a]anthracene, chrysene, benzo[ b]fluoranthene, benzo[ k]fluoranthene, benzo[ a]pyrene, dibenz[ a, h]anthracene and benzo[ ghi]perylene, was determined by high-performance liquid chromatography. After 15 weeks of incubation, the recoveries were less
than 25% for initial amounts of 50 μg (controls above 85%). The recoveries of unlabeled PAH increased in the inoculated samples
with increasing concentrations applied. No correlation could be determined between the number of condensed rings of the PAH
and the recoveries of added PAH. Pleurotus sp. Florida mineralized 53% [ 14C]pyrene, 25% [ 14C]benzo[ a]anthracene and 39% [ 14C]benzo[ a]pyrene to 14CO 2 in the presence of eight unlabeled PAH (50 μg applied) within 15 weeks. During the course of cultivation, Pleurotus sp. Florida degraded more than 40% of the wheat straw substrate. Variation of the initial concentration of PAH did not influence
the extent of degradation of the organic matter.
Received: 16 December 1996 / Received revision: 17 March 1997 / Accepted: 22 March 1997 相似文献
9.
Benzo[ e]pyrene is a pentacyclic aromatic hydrocarbon, which, unlike its structural isomer benzo[ a]pyrene, is not a potent carcinogen or mutagen. The metabolism of benzo[ e]pyrene was studied using the filamentous fungus Cunninghamella elegans ATCC 36112. C. elegans metabolized 65% of the [9, 10, 11, 12- 3H]benzo[ e]pyrene and unlabeled benzo[ e]pyrene added to Sabouraud dextrose broth cultures after 120 h of incubation. Three major metabolites of benzo[ e]pyrene were separated by reversed-phase high-performance liquid chromatography. These metabolites were identified by 1H and 13C NMR, UV-visible, and mass spectral analyses as 3-benzo[ e]pyrenylsulfate, 10-hydroxy-3-benzo[ e]pyrenyl sulfate, and benzo[ e]pyrene 3- O-β-glucopyranoside.
Received: 7 September 1995/Received revision: 14 November 1995/Accepted: 11 December 1995 相似文献
10.
The incorporation of 14C-methanol, 14C-formaldehyde, 14C-formate and 14C-bicarbonate into a methanol-utilizing yeast, Candida N–16, was examined by paper-chromato-graphy and radioautography. At the earliest time period examined, the highest percentage of radioactivity fixed from 14C-methanol or 14C-formaIdehyde into methanol-grown cells was found in fructose phosphate. The percentage distribution of radioactivity in fructose phosphate decreased as time elapsed. The radioactivity fixed from these compounds into glucose-grown cells was negligible compared with that fixed into methanol-grown cells. The incorporation of 14C-formate into methanol-grown cells was extremely low. The highest percentage of radioactivity fixed for short time incubation was found in serine. The incorporation pattern of glucose-grown cells was similar to that of methanol-grown cells. At the earliest time period, over 70% of radioactivity fixed from 14C-bicarbonate into methanol- or glucose-grown cells was found in aspartate. These results suggest that in Candida N–16 methanol is specifically assimilated by a route with hexose phosphate as a primary stable intermediate. 相似文献
11.
Binding of benzo(a)pyrene (B(a)P) to nuclei isolated from rat liver was investigated. After incubation with 14C-B(a)P, the nuclei were subfractionated into an envelope fraction, two chromatin fractions and a matrix fraction. About 50% of the B(a)P that entered the nuclei was associated with the matrix fraction. Covalently bound B(a)P in the matrix fraction also exceeded that in the chromatin fractions. The radioactivity of 14C-B(a)P attained by the matrix DNA was 3–5 times higher than that attained by the chromatin DNAs. These findings suggest that the nuclear matrix is a major intranuclear binding site of B(a)P. 相似文献
12.
The possibility of lysine formation from α,ε-diaminopimelate (DAP), acetate, aspartate or α-aminoadipate (AAA) in rumen ciliates was examined. DAP-1,7- 14C added to the medium was decarboxylated and converted to radioactive lysine in great amounts and radioactive pipecolate in small amounts by rumen ciliates. Difference of the ability to form lysine from DAP between genus Entodinium and Diplodinium was not observed. With sodium acetate-U- 14C, amino acids fraction of the supernatant fluid of the incubation medium and ciliates contained only 0.56 and 0.59% of the total radioactivity, respectively. In the case of l-aspartate-U- 14C, 95.1% of the radioactivity of the supernatant fluid desalted and 62.2% of the radioactivity incorporated into ciliates (1.5% of the total radioactivity) remained as aspartate. Autoradiograms revealed the negligible spots of lysine in ciliates in both cases. AAA-6- 14C remained almost unchanged, even after incubation with rumen ciliates. 相似文献
13.
Summary The binding of radioactivity from 14C-penicillin G labelled in the acyl side chain to Proteus mirabilis D 52 was examined.Under the conditions of the binding assay about 90% of the cells lost their viability upon saturation with radioactivity from 14C-penicillin G which required 18 g penicillin G/mg dry weight of cells and an incubation time of 2 h at 37° C.Examination of 6-aminopenicillanic acid showed that this compound, in contrast to grampositive bacteria, has little effect on the binding of radioactivity from 14C-penicillin G to P. mirabilis D 52. In contrast to 6-aminopenicillanic acid, inhibition of binding of radioactivity from 14C-penicillin G to P. mirabilis D 52 is obtained with phenacetylglycine, a compound considered as structural analogue of the acyl side chain in penicillin G. In addition, this compound interferes with a basic property of penicillin G in that in its presence formation of sphaeroplasts is prevented. A reaction, specific for gramnegative bacteria, is proposed in which the acyl side chain of penicillin G is transfered to a cellular component. 相似文献
14.
The metabolic fate of the non-physiological synthetic dipeptide, sarcosyl-[2- 14C]glycine, was investigated in normal young rats in vivo and in vitro compared to that of seryl-[2- 14C]glycine as a typical example of common physiological dipeptides. The radioactive dipeptides were synthesized from sarcosine or L-serine and [2- 14C]glycine in our laboratory. When radioactive sarcosylglycine was given intraperitoneally, about 30% of the dose was excreted in the urine, and more than 90% of the urinary radioactivity was present in the sarcosylglycine fraction. The recovery of radioactivity in the the expired carbon dioxide and body protein was 8 and 50% of the dose, respectively, during a 24-h period. When the labeled serylglycine was given, the recovery of radioactivity in the urine was 8% of the dose, and 15% in the expired carbon dioxide. In slices of the kidney, liver and small intestine from normal rats, serylglycine was rapidly and almost completely hydrolyzed, and a large amount of free glycine was released. However, sarcosylglycine was hardly hydrolyzed to the corresponding amino acids in the liver and small intestine, and only slightly in the kidney. These results suggest that a considerable amount of sarcosylglycine given intraperitoneally was rapidly excreted into the urine of normal young rats, reflecting less sensitivity to hydrolysis by tissue peptidase(s) when compared to serylglycine. 相似文献
15.
Summary Extensive biodegradation of [ 14C]-2,4,5-trichlorophenoxyacetic acid ([ 14C]-2,4,5-T) by the white rot fungus Phanerochaete chrysosporium was demonstrated in nutrient nitrogen-limited aqueous cultures and in [ 14C]-2,4,5-T-contaminated soil inoculated with this fungus and supplemented with ground corn cobs. After incubation of [ 14C]-2,4,5-T with aqueous cultures of the fungus for 30 days, 62.0%±2.0% of the [ 14C]-2,4,5-T initially present was degraded to 14CO 2. Mass balance analysis demonstrated that water soluble metabolites were formed during degradation, and HPLC and thin layer chromatography (TLC) of methylene chloride-extractable material revealed the presence of polar and non-polar [ 14C]-2,4,5-T metabolites. It was also shown that only 5% of the [ 14C]-2,4,5-T initially present in cultures remained as undegraded [ 14C]-2,4,5-T. In incubations composed of [ 14C]-2,4,5-T-contaminated soil, ground corn cobs, and 40% (w/w) water, 32.5%±3.6% of the [ 14C]-2,4,5-T initially present was converted to 14CO 2 after 30 days of incubation. These results suggest that it may be possible to develop practical systems based on the use of this fungus to detoxify 2,4,5-T-contaminated water and soil. 相似文献
16.
Studies were conducted to determine the fate of 14C-maleic hydrazide injected into the stem xylem of 1-year-old silver maple ( Acer saccharinum L.) and American sycamore ( Platanus occidentalis L.) seedlings. Maleic hydrazide was found to translocate to all parts of the plant within 1 day after treatment. The autoradiographs indicated that the radioactivity was accumulated in meristematic regions of the leaves. A significant amount (over 15% of the applied 14C) was exuded out of the roots into the nutrient solution after 30 days. The 14C in the nutrient solution was in the form of unchanged maleic hydrazide, whereas in plant tissue a metabolite possibly a conjugate with sugar was formed. With the passage of time, the amount of metabolite seemed to increase in proportion to that of maleic hydrazide. Approximately 30% of the applied 14C was unextractable with methanol after 30 days. 相似文献
17.
The white rot fungus, Pleurotus ostreatus, metabolized four soil adsorbed polycyclic aromatic hydrocarbons: 50% of pyrene (0.1 mg g –1 dry soil), 68% of anthracene and 63% of phenanthrene were mineralized after 21 d. Biodegradation was increased to 75%, 80% and 75%, respectively of the initial concentration when 0.15% Tween 40 was added. Biodegradation of pyrene in the presence of surfactant and H 2O 2 (1.0 mM) was 90%. Benz[a]pyrene was also oxidized by Pleurotus ostreatus but it is not mineralized. 相似文献
18.
The fate of orally administered [ 14C]cephalothin has been studied in the rat. This antibiotic undergoes degradation in the gut followed by the subsequent absorption of a portion of the degradation products. About 50% of the administered radioactivity appears in the urine as a mixture of thienylacetylglycine, thienylacetamidoethanol and an unidentified polar metabolite. Evidence is presented indicating that thienylacetamidoethanol arises by the enzymic reduction of a metabolic intermediate, thienylacetamidoacetaldehyde. The metabolic fate of cephalothin is very similar to that of cephaloram reported earlier. The fate of [ 14C]cephaloridine and 7-phenoxy[1- 14C]acetamidocephalosporin was also investigated. In addition to the expected metabolites, about 5% of the cephaloridine dose is absorbed unchanged. With 7-phenoxy[1- 14C]acetamidocephalosporin, 15% of the dose is recovered in urine as deacetyl-7-phenoxy[1- 14C]acetamidocephalosporin. 相似文献
19.
Summary The superiority of polyacrylic acid used as a buffer at 0.25% (w/v) during biodegradation of high molecular weight 14C -labeled lignosulfonates (LS) by the white rot fungus Sporotrichum pulverulentum is demonstrated. Compared to 2,2-dimethylsuccinate (DMS) the release of 14CO 2 from the LS occurs earlier, does not show the levelling-off symptom and reaches higher levels. Changes in pH values of the medium cannot be correlated with the stimulating effects of polyacrylic acid on the ligninolytic activity of the fungus. It seems that interaction between LS and also of dehydropolymers of coniferyl alcohol (DHP) with the polymeric buffer increases the accessibility to the fungus. 相似文献
20.
Summary The distribution of radioactivity in ethanol-water-soluble compounds after short periods of photosynthetic incorporation of 14CO 2 is consistent with the operation of the photosynthetic carbon reduction (PCR) cycle in the fresh water diatom Navicula pelliculosa. Incorporation of 14CO 2 for extended time periods established the presence of the intermediates of the PCR and tricarboxylic acid (TCA) cycles, amino acids, and organic acids; free sugars were not observed. The main labelled soluble carbohydrate was a glucan. Hydrolysis of the radioactive insoluble material indicated the presence of carbohydrates containing several distinct sugars, and proteins with the usual amino-acid composition. During silicon starvation of exponentially growing cultures, rates of incorporation of both 32P
i
and 14CO 2 decreased. Incorporation into the lipid increased, with a corresponding decrease into protein and carbohydrate. Reintroduction of Si to staryed cells led to an increased rate of incorporation of both isotopes, and transient changes in the radioactivity in most metabolic intermediates investigated. After 30 min the radioactivity in all PCR cycle intermediates, except phosphoglyceric acid, had increased by about 300%. The radioactivity of citrate and -keto-glutarate increased, whereas that of other TCA-cycle intermediates decreased. An initial decrease in the levels of glutamate, aspartate and glutamine was apparently reversed by cleavage of glutamate-aspartate peptides, as radioactivity of other amino acids increased. Incorporation into the soluble glucan and into protein increased markedly although the rate of incorporation into insoluble carbohydrates remained constant. 相似文献
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