红树林细菌Rhodococcus ruber1K降解邻苯二甲酸二丁酯的研究

A di-n-butyl phthalate (DBP)degrading bacterium Rhodococcus ruber was isolated from mangrove soil,and its degrading characteristics were studied.The results showed that the bacterium could grow well on the substrate with DBP as the sole source of carbon and energy,and the DBP of 50 mg稬^-1 could be completely degraded after 48 h.Under aerobic condition,the tentative pathway proposed for DBP degradation was through monoester initially,then phthalic acid,and finally CO₂ and H₂O.     

A direct competitive enzyme-linked immunosorbent assay by antibody coated for diethyl phthalate analysis

A direct competitive enzyme-linked immunosorbent assay (ELISA) has been developed for detection of diethyl phthalate (DEP). Protein-hapten conjugate was synthesized to produce polyclonal antibodies against DEP. Experimental parameters were optimized, including immunoreaction conditions, the dilution ratio of horseradish peroxidase (HRP)-antigen conjugate, time of the antibody coated, effect of pH, and ionic strength. The limit of detection was 0.096 ng/ml, and the linear range was 0.1-3500 ng/ml with a regression coefficient (R²) of 0.9957. Recoveries were between 96.4 and 106.2%. The cross-reactivities of the anti-DEP antibody to six structurally related phthalate esters were less than 9%. The method was successfully applied to the determination of DEP in tap water, river water (Yangtze River), and leachate from plastic drinking bottles. This immunoassay was highly specific, sensitive, rapid, simple, and suitable for DEP monitoring. The results obtained were compared with those obtained using the high-performance liquid chromatography method.     

Biodegradation of dimethyl phthalate by an entomopathogenic nematode symbiont Xenorhabdus indica strain KB-3

Dimethyl phthalate (DMP) a common environmental pollutant is well known for its endocrine disrupting activities. Wide spread use of the plastics and pesticides in agriculture have resulted in DMP pollution in soils. An endosymbiotic bacteria Xenorhabdus indica isolated from entomopathogenic nematode Steinernema thermophilum was investigated for biodegradation of DMP. Biodegradation experiment was conducted for 12 days in minimal salt medium supplemented with beef extract. Quantification of residual DMP by High performance liquid chromatography (HPLC) revealed that maximum degradation (98.75%) occurred at 9th day of incubation along with higher esterase activity (46.94 IU/ml) and growth of bacteria (263.75 μg/ml). The efficacy of purified esterase for degradation of DMP was also investigated. It was observed that enzyme alone transform more than 25.6% of DMP into mono-methyl phthalate (MMP) and phthalic acid (PA) within 24 h, which confirms its role in degradation of DMP. Activity of carboxyl esterase enzyme was also positively correlated (r = 0.88) with biodegradation of DMP. Xenorhabdus completely mineralized the DMP as the two intermediates mono-methyl phthalate (MMP) and phthalic acid were not detected after the incubation period of 12 days. The results suggest that the X. indica was highly efficient in degrading DMP and can be employed for bioremediation of contaminated sites.     

Heat shock protein synthesis is induced by diethyl phthalate but not by di(2-ethylhexyl) phthalate in radish (Raphanus sativus)

The toxicity and effects on protein synthesis of the phthalate esters diethyl phthalate (DEP) and di(2-ethylhexyl) phthalate (DEHP) was studied in radish seedlings (Raphanus sativus cv. Kööpenhaminan tori). Phthalate esters are a class of commercially important compounds used mainly as plasticizers in high molecular-weight polymers such as many plastics. They can enter soil through various routes and can affect plant growth and development. First the effect of DEP and DEHP on the growth of radish seedlings was determined in an aqueous medium. It was found that DEP, but not DEHP, caused retardation of growth in radish. A further investigation on protein synthesis during DEP-stress was executed by in vivo protein labeling combined with two-dimensional gel electrophoresis (2D-PAGE). For comparisons with known stress-induced proteins a similar experiment was done with heat shock, and the induced heat shock proteins (HSPs) were compared with those of DEP-stress. The results showed that certain HSPs can be used as an indicator of DEP-stress, although the synthesis of most HSPs was not affected by DEP. DEP also elicited the synthesis of numerous proteins found only in DEP-treated roots. The toxic effect of phthalate esters and the roles of the induced proteins are discussed.     

Biodegradation of diethyl phthalate by an organic-solvent-tolerant Bacillus subtilis strain 3C3 and effect of phthalate ester coexistence

The contamination and distribution of phthalate esters - synthetic compounds widely used in plastic product production, including food and medical packaging - has raised safety concerns due to their endocrine-disrupting activity and mandated to be treated. Bacillus subtilis strain 3C3, isolated as an organic-solvent-tolerant bacterium, was capable of utilizing diethyl phthalate as a sole carbon source. Biodegradation of diethyl phthalate occurred constitutively without lag period, and its kinetics followed a first-order model. The biodegradability was significantly enhanced with the supplementation of yeast extract as a co-metabolic substrate. In the presence of Tween-80 as a solubilizing agent, cells rapidly degrade a range of short-chain phthalate esters at high concentrations (up to 1000 mg l⁻¹ for diethyl phthalate). The biodegradation of short-chain phthalates in the binary, ternary and quaternary substrate system revealed that the coexistence of other short-chain phthalates had no significant influence on the biodegradation of diethyl phthalate, and vice versa. These results substantiated that B. subtilis strain 3C3 has potential application as a bioaugmented bacterial culture for bioremediation of phthalates.     

An ultrasensitive gold nanoparticles improved real-time immuno-PCR assay for detecting diethyl phthalate in foodstuff samples

A specific polyclonal antibody targeting diethyl phthalate (DEP) with the higher antibody titer at 1:120,000 has been obtained, and an ultrasensitive and high-throughput direct competitive gold nanoparticles improved real-time immuno-PCR (GNP–rt–IPCR) technique has been developed for detecting DEP in foodstuff samples. Under optimal conditions, a rather low linearity is achieved within a range of 4 pg L⁻¹ to 40 ng L⁻¹, and the limit of detection (LOD) is 1.06 pg L⁻¹. Otherwise, the GNP–rt–IPCR technique is highly selective, with low cross-reactivity values for DEP analogs (<5%). Finally, the concentrations of DEP in foodstuff samples by the GNP–rt–IPCR method range from 0.48 to 41.88 μg kg⁻¹. Satisfactory recoveries (88.39–112.79%) and coefficient of variation values (8.38–12.77%) are obtained. The consistency between the results obtained from GNP–rt–IPCR and gas chromatography–mass spectrometry (GC–MS) is 98.3%, which further proves that GNP–rt–IPCR is an accurate, reliable, rapid, ultrasensitive, and high-throughput method for batch determination of trace amounts of DEP in foodstuff samples.     

Biodegradation of dimethyl phthalate with high removal rates in a packed-bed reactor

Biological treatment of a dimethyl phthalate (DMP)-containing waste stream was evaluated in packed-bed bioreactors using an acclimated mixed bacterial culture. The passive immobilization start-up strategy was successful in the development of a stable biofilm on the packing material in the reactor. Nutrient supplementation significantly improved the removal efficiency. High removal rates with 100% efficiencies of DMP removal were achieved up to the phthalate-loading rate of 560 g/m³ h.     

Diethyl phthalate degradation by the freeze-dried,entrapped Bacillus subtilis strain 3C3

Microbial degradation is the key treatment for diethyl phthalate (DEP) of which the efficacy is subdued by substrate toxicity. DEP-degrading Bacillus subtilis strain 3C3 adopted cell size alteration as one of the adaptive mechanisms in response to DEP stress at high concentrations. Nevertheless, to enhance cell tolerance in the protected environment and to facilitate practical treatment operation, cell entrapment was optimized with the entrapment yield at 89 ± 1% in a modified minimal salt medium-containing alginate matrix and the freeze-dried, entrapped cells were then formulated. Among several compounds tested, incorporation of sucrose proved to be beneficial as a cryoprotectant sustaining cell biodegradation efficiency (97%) and viability (≥90%) during freeze drying, storage under a vacuum condition at low temperatures, rehydration and as an additional matrix filler to reinforce the bead structure. The effective DEP treatment of the formulated, entrapped cells was demonstrated in a packed bed continuous system in which 70% DEP removal at hydraulic retention time (HRT) of 30 min was occurred and was enhanced up to 90% when HRT was increased to 60 min. The work demonstrates an effective preparation and a potential application of the formulated entrapped DEP-degrading cells for DEP treatment.     

Biodegradation of wheat stubbles by soil micro-organisms and role of the products on soil fertility

Summary Soil microorganisms caused considerable degradation of wheat stubbles under laboratory conditions. Mixtures of different organisms proved to be more efficient than individual organisms in degrading lignin, holocellulose and nitrogenous substances which constitute the major components in stubble. Lignin and holocellulose content in fresh stubble was about 25% and 60% of dry weight respectively. Degradation of these compounds caused an increase in simpler components like soluble carbohydrates. Degradation of nitrogenous substances (represented by 0.7% total nitrogen in fresh stubbes) caused accretion in the soluble nitrogen of the degraded product. In most cases, these products proved to be important in improving fertility of the soil thereby causing significant promotion of growth of crops like maize and rice.     

Biodegradation of N-Methylpyrrolidone by Paracoccus sp. NMD-4 and its degradation pathway

N-Methylpyrrolidone (NMP), a kind of nitrogen-containing heterocyclic pollutant, is widely used in chemical industry. Microbial degradation is an important environmental fate process in soil and water, however, the microbial metabolic mechanism is still unknown. Strain NMD-4, capable of utilizing NMP as the sole source of carbon and nitrogen, was isolated from the activated sludge of a pesticide plant in Jiangsu, China, and identified as Paracoccus sp. based on its physiological–biochemical properties, as well as 16S rRNA gene sequence analysis. The degradation characteristic of NMP by strain NMD-4 was studied in a liquid culture, and the metabolic pathway of NMP by the strain was investigated. Two metabolites, 1-methyl-2,5-pyrrolidinedione and succinic acid, were detected and identified by liquid chromatography-mass spectrometry analysis, and a plausible microbial degradation pathway of NMP was proposed by the first time.     

Biodegradation of oily sludge in Kuwait soil

Soil microorganisms were not inhibited by mixing oily sludge in soil up to 8.7% (w/w) oil (15% sludge). Adding NH ₄ ⁺ and phosphate increased microbial activity. Microbial activity was also affected by seasonal variation. Thermotolerant microorganisms were more predominant during the summer. After 29 months, 72%, 84%, and 83% of the soil was degraded in fertilized soils dosed with 2.9, 5.8 and 8.7% oil, respectively.     

Hydrolysis of diethyl diferulates by a tannase from Aspergillus oryzae

Diferulic acid forms cross-links in naturally occurring plant cell wall polymers such as arabinoxylans and pectins. We have used model ethyl esterified substrates to find enzymes able to break these cross-links. A tannase from Aspergillus oryzae exhibited esterase activity on several synthetic ethyl esterified diferulates. The efficiency of this esterase activity on most diferulates is low compared to that of a cinnamoyl esterase, FAEA, from Aspergillus niger. Of the diferulate substrates assayed, tannase was most efficient at hydrolysing the first ester bond of the 5–5- type of dimer. Importantly and unlike the cinnamoyl esterase, tannase from A. oryzae is able to hydrolyse both ester bonds from the 8–5-benzofuran dimer, thus forming the corresponding free acid product. These results suggest that tannases may contribute to plant cell wall degradation by cleaving some of the cross-links existing between cell wall polymers.     

Metabolism of butyl benzyl phthalate by Gordonia sp. strain MTCC 4818

The microbial degradative characteristics of butyl benzyl phthalate (BBP) were investigated by the Gordonia sp. strain MTCC 4818 isolated from creosote-contaminated soil. The test organism can utilize a number of phthalate esters as sole sources of carbon and energy, where BBP was totally degraded within 4 days under shake culture conditions. High performance liquid chromatography profile of the metabolites isolated from spent culture indicated the accumulation of two major products apart from phthalic acid (PA), which were characterized by gas chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy as mono-n-butyl phthalate (MBuP) and monobenzyl phthalate (MBzP). Neither of the metabolites, MBuP, MBzP or PA, supported growth of the test organism, while in resting cell transformation, the monoesters were hydrolyzed to PA to a very minor extent, which was found to be a dead-end product in the degradation process. On the other hand, the test organism grew well on benzyl alcohol and butanol, the hydrolyzed products of BBP. The esterase(s) was found to be inducible in nature and can hydrolyze in vitro the seven different phthalate diesters tested to their corresponding monoesters irrespective of their support to the growth of the test organism.     

Behavior of dimethyl phthalate (DMP) in simulated landfill bioreactors with different operation modes

The behavior of dimethyl phthalate (DMP) from municipal solid waste (MSW) in the leachate and refuse of two simulated landfill bioreactors was compared. In one reactor, the leachate was circulated between a landfill and a methanogenic reactor, while the other reactor was operated using direct recirculation of the leachate. The results revealed that the original concentration of DMP in the refuse was approximately 3.3 μg g⁻¹, and the concentration decreased greatly during decomposition of the waste in both reactors. The major loss of DMP from the landfill occurred in an active methanogenic environment in the later period, while the environment was acidic due to a high concentration of chemical oxygen demand (COD), volatile fatty acids (VFA), and contained a large volume of biologically degradable material (BDM) during the early stage. In addition, a high correlation was found between the residual DMP concentrations and the BDM of the refuse in both systems. Circulating the leachate between the landfill and a methanogenic reactor resulted in an increase in the biodegradability of MSW and the degree of waste stabilization. Furthermore, the removal of DMP was enhanced 14% in the landfill that was operated in conjunction with the methanogenic reactor when compared to the landfill in which there was direct leachate recirculation.     

Responses of soil microbial community and enzymes during plant-assisted biodegradation of di-(2-ethylhexyl) phthalate and pyrene

Abstract

A pot experiment was conducted to explore the plant-assisted degradation efficiency of di-(2-ethylhexyl) phthalate (DEHP) and pyrene. Three plant species: Ceylon spinach, sunflower, and leaf mustard were cultivated in co-contaminated soils under three contamination levels: control (T0), 20?mg kg^?1 (T20), and 50?mg kg^?1 (T50). The results showed that a higher DEHP and pyrene degradation efficiency was observed evidently in planted cases, increasing from 42 to 53–59% (T0), 61 to 65–76% (T20) and 52 to 68–78% (T50) for DEHP, and from 22 to 30–49% (T0), 58 to 62–72% (T20), and 54 to 57–70% (T50) for pyrene. Under T20 contamination level, soil phospholipid fatty-acid analysis depicted the increased microbial biomass in rhizosphere, especially the arbuscular mycorrhizal fungus that is effective for the degradation of organic pollutants. The study also revealed that the activities of dehydrogenase, acid phosphomonoesterase, urease, and phenol oxidase negatively correlated with pollutant concentration. In general, the removal rate of DEHP and pyrene was highest in the soil planted with leaf mustard for each contamination level considered. For soils at T20 level, sunflower and leaf mustard appeared as interesting phytoremediation plants due to the improved removal rates of organic pollutants and the soil microbial activity.     

Biodegradation of p-toluenesulphonamide by a Pseudomonas sp.

A bacterium capable of utilising p-toluenesulphonamide was isolated from activated sludge. The isolated strain designated PTSA was identified as a Pseudomonas sp. using chemotaxonomic and genetic studies. Pseudomonas PTSA grew on p-toluenesulphonamide in a chemostat with approximately 90% release of sulphate and 80% release of ammonium. The isolate was also able to grow on 4-carboxybenzenesulphonamide and 3,4-dihydroxybenzoate but did not grow on p-toluenesulphonate. The transient appearance of 4-hydroxymethylbenzenesulphonamide and 4-carboxybenzenesulphonamide during p-toluenesulphonamide degradation proves oxidation of the methyl group is the initial attack in the biodegradation pathway. Both metabolites of p-toluenesulphonamide degradation were identified by high-performance liquid chromatography-mass spectrometry. 4-Carboxybenzenesulphonamide is probably converted into 3,4-dihydroxybenzoate and amidosulphurous acid. The latter is a chemically unstable compound in aqueous solutions and immediately converted into sulphite and ammonium. Both sulphite and ammonium were formed during degradation of 4-carboxybenzenesulphonamide.     

Biodegradation of a dilute waste oil emulsion applied to soil

Summary The use of land treatment for disposal of a dilute waste oil emulsion generated by an aluminum rolling industry was investigated. Major components of the waste, identified by gas chromatography and mass spectrometry, were linear and branched (C₁₂–C₂₅) and fatty acid emulsifiers (primarily, isomers of oleic acid). Hexadecane and pristane were readily biodegraded in vitro when added to soil collected from the waste disposal site. Hydrocarbons and fatty acids extracted from the waste were similarly, biodegraded, however, the rate of decomposition may have depended on the history of waste applications to soil collected from the land treatment site. The apparent half-life of resolvable waste hydrocarbons and fatty acids was 9.5 days in soil which had received waste applications averaging 25.4l m^–2 wk^–1. In contrast, soil receiving either 50.8l m^–2 wk^–1 or no waste application during summer 1987 apparent exhibited half-lives of 28.1 and 60.3 days, respectively. Waste components were restricted to the upper 48 cm of the soil cores collected from the disposal site. Core samples also provided evidence for biodegradation of hydrocarbons and fatty acids as well as an accumulation of other compounds not readily resolvable by gas chromatographyPublished with the approval of the Director of the West Virginia University Agriculture and Forestry Experiment Station as Scientific Article # 2122.     

土壤中乙草胺的微生物降解及其对防除稗草持效性的影响

采用气相色谱法和生物测定法,研究了土壤中乙草胺的微生物降解及其对防除稗草持效性的影响.结果表明,在同样的湿度和温度条件下,当添加到土壤中的乙草胺浓度为125、25和5.0 mg·kg^-1时,相同浓度的乙草胺在非灭菌土壤中的半衰期显著短于灭菌土壤,说明土壤微生物对乙草胺有明显的降解作用.三大主要菌群分离培养物降解实验与上述结果一致.生物测定结果表明,乙草胺在非灭菌土壤中防除稗草的持效期显著短于灭菌土壤,微生物的存在缩短了乙草胺在土壤中的滞留时间,从而降低了乙草胺防除稗草的持效性.