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1.
Isomers of 1,2,3,4,5,6-hexachlorocyclohexane (HCH) were some of the most widely used pesticides. Despite reduction in their production and use, HCH isomers present a serious environmental hazard. In this study, two bacterial isolates (LIN-1 and LIN-3) that can grow on gamma-HCH as a sole source of carbon and energy were isolated from an enrichment culture. In liquid cultures of LIN-1 and LIN-3, 25.0 and 45.5% removal of gamma-HCH, respectively, were achieved in 2 weeks. LIN-3 was identified as Pandoraea sp. by 16S rRNA gene sequence analysis (99% identity). Pandoraea sp. substantially degraded both gamma- and alpha-HCH isomers at concentrations of 10-200 mg L(-1) in liquid cultures. After 8 weeks of incubation in liquid culture, 89.9 and 93.3% of the gamma- and alpha-HCH isomers declined, respectively, at an initial concentration of 150 mg L(-1). In soil slurry cultures of Pandoraea sp., simulating a soil slurry phase bioremediation treatment, substantial decreases in the levels of the HCH isomers were observed at concentrations of 50-200 mg L(-1). After 9 weeks, 59.6 and 53.3% biodegradations of gamma- and alpha-HCH isomers, respectively, were achieved at 150 mg L(-1). Using two 23-mer oligonucloetide primers targeting the 330 bp region of the 16S rRNA gene of Pandoraea sp., an approximately 330 bp PCR product was successfully amplified from DNA templates prepared from bacterial colonies and soil slurry culture. This system provides a direct and rapid PCR-based molecular tool for tracking Pandoraea sp. strain LIN-3 in water and soils. These results have implied implications for the treatment of soils and water contaminated with HCH isomers.  相似文献   

2.
This study was conducted to monitor the biodegradation of alpha-, beta-, gamma-, and delta-hexachlorocyclohexane (HCH) isomers in liquid culture by a Pandoraea species and determine the influence of pH and temperature on the biodegradation of alpha- and gamma-HCH in liquid as well as in soil slurry cultures. The Pandoraea species degraded 79.4% delta-HCH and 34.3% gamma-HCH in liquid culture at 4 weeks of incubation. alpha- and beta-HCH exhibited almost identical rates (41.6 and 42.4%, respectively) of degradation. The highest degradation of alpha- and gamma-HCH (67.1 and 60.2%, respectively) was observed at an initial pH of 8.0 in liquid; 58.4 and 51.7% rates of degradation of alpha- and gamma-HCH, respectively, at an initial pH of 9.0 were found in soil slurry cultures. An incubation temperature of 30 degrees C was optimum for effective degradation of alpha- and gamma-HCH isomers (62.5 and 57.7%, respectively) in liquid culture, and 54.3 and 51.9% rates of degradation of alpha- and gamma-HCH isomers, respectively, were found in a soil slurry. Increasing the soil/water ratio decreased the extent of degradation of both HCH isomers. Degradation of HCH isomers occurred concomitant with bacterial growth. Byproducts of growth from Pandoraea species significantly decreased the pH of the liquid and the soil slurry during the growth on HCH isomers. The results of this study suggest that this bacterial strain may effectively be used for remediating polluted sites and water contaminated with different HCH isomers over a range of environmental conditions.  相似文献   

3.
This study assesses the role of the blue-green algal species present in the soil in the dissipation of endosulfan and its metabolites in the soil environment. Two Anabaena species, Anabaena sp. PCC 7120 and Anabaena flos-aquae, were used in this study. Anabaena sp. PCC 7120 produced three principal biotransformation compounds, chiefly endosulfan diol (endodiol), and minor amounts of endosulfan hydroxyether and endosulfan lactone. Trace amounts of endosulfan sulfate were detected. In comparison, the biotransformation of endosulfan by Anabaena flos-aquae yielded mainly endodiol with minor amounts of endosulfan sulfate. An unknown compound was produced up to 70% from endosulfan spiked in the medium inoculated by A. flos-aquae after 8 days of incubation. Therefore, the endosulfan fate was dependent on the species. Within 1 day of incubation, two Anabaena species produced low amounts of beta-endosulfan after application of alpha-endosulfan. These results suggest the presence of isomerase in the Anabaena species. Further studies using a fermentor to control the medium pH at 7.2 to minimize chemical hydrolysis of endosulfan revealed a major production of endodiol with minor amounts of endosulfan sulfate and the unknown compound. These results showed that the production of the unknown compound might be dependent on the alkaline pH in the medium and that the production of endodiol by A. flos-aquae might be biologically controlled. This study showed that two algal species could contribute in the detoxification pathways of endosulfan in the soil environment.  相似文献   

4.
The dissipation and persistence of endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin 3-oxide) applied to field-grown tomato (Lycopersicon esculentum) were studied at a vegetable-growing location in Ghana. Plant tissue samples and cropped soil collected at 2 h-14 days and 8 h-112 days, respectively, after application, were analyzed by gas chromatography-electron capture detection (63Ni) to determine the content and dissipation rate of endosulfan isomers (alpha- and beta-endosulfan) and the major metabolite, endosulfan sulfate. After two foliar applications of commercial endosulfan at 500 g of active ingredient/hectare, the first-order reaction kinetic was confirmed to describe the dissipation of endosulfan residues in tomato foliage and cropped soil. However, functions that best fit the experimental data were the biphasic process for foliage and the monophasic process for cropped soil. Calculated DT 50 and DT 90 values for endosulfan residues in cropped soil were not significantly (p<0.05) different for each of the two isomers.  相似文献   

5.
Endosulfan, an endocrine disrupting chemical, is a widely used cyclodiene organochlorine pesticide worldwide, and it blocks neuronal GABA(A)-gated chloride channels in mammals and aquatic organisms. Endosulfan and its metabolites, such as endosulfan sulfate, are persistent in environments and are considered as toxic chemicals. For bioremediation of endosulfan, in this study, an attempt was made to isolate an endosulfan and endosulfan sulfate degrading bacterium from endosulfan-polluted agricultural soil. Through repetitive enrichment and successive subculture using endosulfan or endosulfan sulfate as the sole carbon source, a bacterium KS-2P was isolated. The KS-2P was identified as Pseudomonas sp. on the basis of the results of a 16S rDNA sequencing analysis and MIDI test. The degradation ratios for endosulfan or endosulfan sulfate in minimal medium containing endosulfan (23.5 microg mL(-1)) or endosulfan sulfate (21 microg mL(-1)) were 52% and 71%, respectively. Our results suggest that Pseudomonas sp. KS-2P has potential as a biocatalyst for endosulfan bioremediation.  相似文献   

6.
土壤中酚的微生物降解试验研究   总被引:1,自引:0,他引:1  
杨军  朱琨  黄涛 《土壤通报》2006,37(1):130-133
为研究微生物对土壤中酚污染的净化能力,培养分离出了一株能有效降解酚的芽孢杆菌,并通过土柱试验研究了其降解特性和影响因素。结果表明,该芽孢杆菌在温度为16℃~30℃时,对浓度为50~500mg L-1范围内的酚污染(相当于10~l00μg g-1的土壤酚含量)降解率高达96.1%以上,且对pH值适应范围较大。  相似文献   

7.
The processing factors (pesticide concentration found in olive oil/pesticide concentration found in olives) of azinphos methyl, chlorpyrifos, lambda-cyhalothrin, deltamethrin, diazinon, dimethoate, endosulfan, and fenthion were determined in olive oil production process in various laboratory-scale olive oil extractions based on three- or two-phase centrifugation systems in comparison with samples collected during olive oil extractions in conventional olive mills located at different olive oil production areas in Greece. Pesticide analyses were performed using a multiresidue method developed in our laboratory for the determination of different insecticides and herbicides in olive oil by solid-phase extraction techniques coupled to gas chromatography detection (electron capture detection and nitrogen phosphorus detection), optimized, and validated for olive fruits sample preparation. Processing factors were found to vary among the different pesticides studied. Water addition in the oil extraction procedure (as in a three-phase centrifugation system) was found to decrease the processing factors of dimethoate, alpha-endosulfan, diazinon, and chlorpyrifos, whereas those of fenthion, azinphos methyl, beta-endosulfan, lambda-cyhalothrin, and deltamethrin residues were not affected. The water content of olives processed was found to proportionally affect pesticide processing factors. Fenthion sulfoxide and endosulfan sulfate were the major metabolites of fenthion and endosulfan, respectively, that were detected in laboratory-produced olive oils, but only the concentration of fenthion sulfoxide was found to increase with the increase of water addition in the olive oil extraction process.  相似文献   

8.
Stoichiometric and kinetic values of phenolics against DPPH (2,2-diphenyl-1-picrylhydrazyl) were determined for Andean purple corn (Zea mays L.) and red sweetpotato (Ipomoea batatas). Both crops had higher antioxidant capacity and antiradical kinetics than blueberries and higher or similar anthocyanin and phenolic contents. The second-order rate constant (k(2)) was 1.56, 1.12, 0.57, and 0.26 (mg antiradical/mL)(-1) s(-1) for red sweetpotato, Trolox, purple corn, and blueberry, respectively. On the molar basis of active hydroxyl groups, k(2)' showed the same order as for k(2). Corn cob and sweetpotato endodermis contributed the most in phenolic compounds and antioxidant capacity. Both crops studied can be considered as excellent novel sources of natural antioxidants for the functional food and dietary supplement markets.  相似文献   

9.
Dimethyl dicarbonate (DMDC) was added to grape must and to synthetic media and results showed that, at 20 degrees C, 150 mg.L(-)(1) DMDC completely inhibited the fermentation of a grape must that was previously inoculated with 10(6) cells.mL(-)(1) Saccharomyces bayanus and Saccharomyces uvarum. Brettanomyces intermedius, Candida guilliermondii, Hansenula jadinii, Hansenula petersonii, Kloeckera apiculata, Pichia membranaefaciens, and Saccharomyces cerevisiae were inhibited by 250 mg.L(-)(1). Candida valida was inhibited in the presence of 350 mg.L(-)(1), whereas Hanseniaspora osmophila, Saccharomycodes ludwigii, Schizosaccharomyces pombe, and Zygosaccharomyces bailii required 400 mg.L(-)(1). Delay of fermentation (but not inhibition) was noted in the presence of 400 mg.L(-)(1) for the following cultures: Brettanomyces anomalus, Hanseniaspora uvarum, Metschnikowia pulcherrima, Schizosaccharomyces japonicus, Torulaspora delbrueckii, and Zygosaccharomyces florentinus. Acetobacter aceti and Lactobacillus sp. were completely inhibited using 1000 and 500 mg.L(-)(1) DMDC, respectively. The fermentation of a grape must inoculated with 10(6) cells.mL(-)(1) of different wine yeasts was delayed for 4 days after the prior addition of 200 mg.L(-)(1) of DMDC; 200 mg.L(-)(1) DMDC did not show any residual inhibitory effect after 12 h, nor did 300 mg.L(-)(1) 24 h after the addition. In cellar experiments, indigenously contaminated grape musts (with and without skins) showed a delay in fermentation of 48 h after the addition of only 50 mg.L(-)(1) DMDC. The possibility of using DMDC (as pure grade as commercially available) in grape must as a disinfectant for the decontamination of musts indigenously contaminated with wild yeast should be considered seriously, despite its apparent low solubility in water.  相似文献   

10.
This aim of the study is to investigate a halophilic bacterium Hortaea sp. B15, isolated from petroleum-contaminated soil for biodegradation of phenanthrene. Hortaea sp. B15 has the ability to completely degrade phenanthrene (100 mg/L) under salinity 10% within 1-week incubation. The metabolitic product of phenanthrene was identified and assayed by using ultraviolet-visible spectrophotometer and mass spectral analysis. Result revealed that Hortaea sp. B15 metabolized phenanthrene to form 9,10-phenanthrene quinone, salicylic acid, and gentisic acid. Hortaea sp. B15 has an efficient utilization of phenanthrene in high-saline liquid medium. All the results indicated that the fungus has a promising application for the study of high-molecular-weight PAH biodegradation and contaminated saline-alkali soil bioremediation.  相似文献   

11.
The browning of glucose-fructose-glycine mixtures involves parallel glucose-glycine and fructose-glycine reactions, which share a common intermediate, the immediate precursor of melanoidins in the kinetic model. At pH 5.5, 55 degrees C glucose is converted into this intermediate in a two step process where k(1) = (7.8 +/- 1.1) x 10(-)(4) mol L(-)(1) h(-)(1) and k(2) = (1.84 +/- 0.31) x 10(-)(3) h(-)(1) according to established kinetics, whereas fructose is converted into this intermediate in a single step where k(4) = 5.32 x 10(-)(5)()()mol L(-)(1) h(-)(1). The intermediate is converted to melanoidins in a single rate limiting process where k(mix) = 0.0177 h(-)(1) and the molar extinction coefficient (based on the concentration of sugar converted) of the melanoidins so formed is 1073 +/- 4 mol(-)(1) L cm(-)(1). Whereas the value of k(mix) is the same when the individual sugars undergo browning, the value of the molar extinction coefficient is similar to that for melanoidins from the glucose-glycine reaction (955 +/- 45 mol(-)(1) L cm(-)(1)) but it is approximately double the value for melanoidins from the fructose-glycine reaction (478 +/- 18 mol(-)(1) L cm(-)(1)). This is the reason that the effects of glucose and fructose on the rate of browning are synergistic.  相似文献   

12.
We enzymatically modified rice starch to produce highly branched amylopectin and amylose and analyzed the resulting structural changes. To prepare the highly branched amylopectin cluster (HBAPC), we first treated waxy rice starch with Thermus scotoductus alpha-glucanotransferase (TSalphaGT), followed by treatment with Bacillus stearothermophilus maltogenic amylase (BSMA). Highly branched amylose (HBA) was prepared by incubating amylose with Bacillus subtilis 168 branching enzyme (BBE) and subsequently treating it with BSMA. The molecular weight of TSalphaGT-treated waxy rice starch was reduced from 8.9 x 10(8) to 1.2 x 10(5) Da, indicating that the alpha-1,4 glucosidic linkage of the segment between amylopectin clusters was hydrolyzed. Analysis of the amylopectin cluster side chains revealed that a rearrangement in the side-chain length distribution occurred. Furthermore, HBAPC and HBA were found to contain significant numbers of branched maltooligosaccharide side chains. In short, amylopectin molecules of waxy rice starch were hydrolyzed into amylopectin clusters by TSalphaGT in the enzymatic modification process, and then further branched by transglycosylation using BSMA. HBAPC and HBA showed higher water solubility and stability against retrogradation than amylopectin clusters or branched amylose. The hydrolysis rates of HBAPC and HBA by glucoamylase and alpha-amylase greatly decreased. The k cat/ K m value of glucoamylase acting on the amylopectin cluster was 45.94 s(-1)(mg/mL)(-1) and that for glucoamylase acting on HBAPC was 11.10 s(-1)(mg/mL)(-1), indicating that HBAPC was 4-fold less susceptible to glucoamylase. The k cat/ K m value for HBA was 15.90 s(-1)(mg/mL)(-1), or about three times less than that for branched amylose. The k cat/ K m values of porcine pancreatic alpha-amylase for HBAPC and HBA were 496 and 588 s(-1)(mg/mL)(-1), respectively, indicating that HBA and HBAPC are less susceptible to hydrolysis by glucoamylase and alpha-amylase. HBAPC and HBA show potential as novel glucan polymers with low digestibility and high water solubility.  相似文献   

13.
The oxidation kinetics and mechanisms of diazinon, an organophosphorus pesticide, by aqueous chlorine were studied under different conditions. The oxidation is of first order with respect to both diazinon and chlorine. The oxidation rate is found to increase with decreasing pH. The second-order rate constants at pH 9. 5, 10.0, 10.5, and 11.0 are determined to be 1.6, 0.64, 0.43, and 0. 32 M(-)(1) s(-)(1), respectively. Based on the rate constants at different temperatures, the activation energy is calculated to be 30 kJ/mol at pH 10.0 with a chlorine-to-diazinon ratio of 11:1, 33 kJ/mol at pH 11.0 with a 11:1 ratio, and 36 kJ/mol at pH 11.0 with a 5:1 ratio, respectively. Diazoxon is identified as the oxidation product by GC-MS. Ion chromatography analysis shows an increase of sulfate concentration as the reaction proceeds, indicating that sulfur is being oxidized to sulfate. This study indicates that oxidation by aqueous chlorine can significantly affect the fate of diazinon in the environment.  相似文献   

14.
Methomyl, an extremely toxic pesticide, is widely used in agriculture. A strain named mdw-1 capable of degrading methomyl rapidly was successfully isolated from activated sludge in this study. It could utilize methomyl as the sole carbon or nitrogen source. The optimal temperature and medium pH for its growth and methomyl biodegradation were 30-C and 7.0, respectively. It was identified as a Paracoccus sp. according to its morphological features, physiological and biochemical characteristics, and phylogenetic analysis based on the sequence of 16S rDNA. Gas chromatography-mass spectrometry (GC-MS) analysis showed that methomyl could be completely transformed to S-methyl-N-hydroxythioacetamidate in 10 h of incubation with the isolate mdw-1.  相似文献   

15.
The role of algae in the persistence, transformation, and bioremediation of two endocrine disrupting chemicals, alpha-endosulfan (a cyclodiene insecticide) and its oxidation product endosulfan sulfate, in soil (incubated under light or in darkness) and a liquid medium was examined. Incubation of soil under light dramatically decreased the persistence of alpha-endosulfan and enhanced its transformation to endosulfan sulfate, over that of dark-incubated soil samples, under both nonflooded and flooded conditions. This enhanced degradation of soil-applied alpha-endosulfan was associated with profuse growth of indigenous phototrophic organisms such as algae in soil incubated under light. Inoculation of soil with green algae, Chlorococcum sp. or Scenedesmus sp., further enhanced the degradation of alpha-endosulfan. The role of algae in alpha-endosulfan degradation was convincingly demonstrated when these algae degraded alpha-endosulfan to endosulfan sulfate, the major metabolite, and endosulfan ether, a minor metabolite, in a defined liquid medium. When a high density of the algal inoculum was used, both metabolites appeared to undergo further degradation as evident from their accumulation only in small amounts and the appearance of an endosulfan-derived aldehyde. Interestingly, beta-endosulfan was detected during degradation of alpha-endosulfan by high density algal cultures. These algae were also capable of degrading endosulfan sulfate but to a lesser extent than alpha-endosulfan. Evidence suggested that both alpha-endosulfan and endosulfan sulfate were immediately sorbed by the algae from the medium, which then effected their degradation. Biosorption, coupled with their biotransformation ability, especially at a high inoculum density, makes algae effective candidates for remediation of alpha-endosulfan-polluted environments.  相似文献   

16.
This paper investigates the potential use of composted cotton gin trash (CCGT) as a pesticide sorption medium in remediation of contaminated tailwater. CCGT was found to contain a large organic matter fraction (25.22%). Sorption of endosulfan sulfate and diuron, using the batch equilibrium method, was rapid but not limited for the range of applied concentrations, with diuron failing to reach equilibrium after two days. The partition K d and organic carbon partition K(OC) coefficients determined diuron ( Kd = 78; K(OC) = 526) and endosulfan sulfate ( Kd = 1500; K(OC) = 10,111) to reside in the solid phase. Limited desorption of diuron and higher range concentrations of endosulfan sulfate (50-100 microg L(-1)) were quantified. Sorption and desorption resulted from hydrophobic and hydrophilic interactions with the humic components of the compost. CCGT was concluded to have a superior sorption capacity to other sorbents reported in the literature, an assessment that requires field substantiation.  相似文献   

17.
Phlorin (3,5-dihydroxyphenyl beta-D-glucopyranoside), an orange peel marker, has been searched in 45 species and varieties of Citrus. The phlorin content was determined by high-pressure liquid chromatography in juices and aqueous peel extracts of these different fruits. The phlorin content in C. reticulata peel extract varies from 0 to 1012 mg L(-)(1) with a mean of 162 mg L(-)(1). On the contrary, phlorin was not found in mandarin and clementine juices except for mandarin "Commune" and "Beauty" (33 and 30 mg L(-)(1), respectively). In the 14 species of oranges and varieties, phlorin was detected in juices and peel extracts with a mean of 22 and 492 mg L(-)(1), respectively, while for grapefruits, means were 108 mg L(-)(1) in juices and 982 mg L(-)(1) for peel extracts. Tangors and tangelos which are hybrids (C. reticulata x C. sinensis and C. reticulata x C. paradisi, respectively) are characterized by the systematic presence of phlorin in peels (mean: 406 and 659 mg L(-)(1), respectively) while in juices its presence could be variable (0-73 mg L(-)(1)). These heterogeneity and values may be explained by the genetic variability of these hybrids and the phlorin content of their parentage group.  相似文献   

18.
This research is a continuation of a study on the behavior of hydrophobic organic compounds in the environment and describes the simultaneous abiotic degradation and sorption of pirimiphos-methyl (O-2-diethylamino-6-methylpyrimidin-4-yl O,O-dimethylphosphorothioate) under controlled conditions in soil/water slurries. A microfiltration-HPLC technique was employed to follow these processes in two well-characterized soils from the Middle Belt region of Nigeria. Rapid sorption of the pesticide occurs during the first 10 min of equilibration and accounted for 37% of the original pirimiphos-methyl in the Rhodic Kandiustalf soil and for 41% of the original concentration in Aquic Ustropept soil. Subsequent slow processes were followed during the remaining 30 days of the experiment. During this time, first-order rate constants for disappearance from solution of pirimiphos-methyl were found to have values of 6.1 x 10(-)(7) and 9.8 x 10(-)(7) s(-)(1) for the Rhodic and Aquic soils, respectively. Similarly, rate constants for production of the product, pyrimidinol, were calculated to be 6.0 x 10(-)(7) and 9.4 x 10(-)(7) s(-)(1) for the Rhodic and Aquic soils, respectively, giving pesticide degradation half-lives of 13 and 8.5 days. Disappearance of the pesticide is discussed in terms of a scheme involving both sorptive uptake by the soil and degradation by hydrolysis in the presence of the soil matrix. The labile sorption capacities for pirimiphos-methyl in the Rhodic and Aquic soils were found to be 0.75 and 0.90 micromol g(-)(1), respectively.  相似文献   

19.
PAHs生物降解程度受多种因素影响。通过筛选驯化PAHs降解菌,研究混合菌对土壤中菲、芘、苯并(a)蒽、苯并(b)荧蒽、苯并(k)荧蒽、茚并(1,2,3-cd)芘的生物降解性能,并考察污染时间对土壤中PAHs降解效果的影响。结果表明,筛选的混合菌具有很强的PAHs降解能力,缩短了PAHs生物降解的半衰期,且PAHs起始降解速率较快,之后趋于平缓。27d内土壤中的菲、芘、苯并(a)蒽、苯并(b)荧蒽、苯并(k)荧蒽、茚并(1,2,3-cd)芘的平均降解率分别为98.14%、89.97%、88.47%、63.55%、65.24%、60.49%,其中菲在5d之内的降解率高于93%。污染210d的土壤中各PAHs的起始降解速率高于污染50d的土壤,因此污染时间越长,PAHs生物降解的停滞期越短。  相似文献   

20.
Low molecular weight carbohydrates in pine nuts from Pinus pinea L. (n = 7) have been studied by gas chromatography-mass spectrometry as their trimethylsilyl oximes. Besides previously reported components, such as glucose, fructose, sucrose, and raffinose, several soluble carbohydrates have been identified for the first time in this product, including saccharides (galactose, maltose, and planteose) and cyclitols (pinitol, galactinol, galactopinitol A1, fagopyritol B1, and other glycosyl-inositols). Most abundant cyclitols were chiro-inositol, fagopyritol B1, and pinitol, with concentrations ranging from 126.7 to 222.1 mg (100 g)(-1), 94.2 to 177.1 mg (100 g)(-1), and 51.2 to 282.8 mg (100 g)(-1), respectively.  相似文献   

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