二(2-乙基己基)邻苯二甲酸酯降解菌的分离和鉴定及其在污染土壤生物修复中的作用

Di-（2-ethylhexyl） phthalate（DEHP） is a high-molecular-weight phthalate ester（PAE） that has been widely used in the manufacture of polyvinylchloride and contributes to environmental pollution.The objectives of the present study were to isolate a DEHP degrader that can utilize DEHP as a carbon source and to investigate its capacity to biodegrade DEHP in both liquid culture and soil.A bacterial strain WJ4 was isolated from an intensively managed vegetable soil,which was contaminated with PAEs.The strain WJ4 was affiliated to the genus Rhodococcus and was able to remove DEHP from soil effectively.A period of only 7 d was required to degrade about 96.4%of DEHP(200 mg L^-1) in the liquid culture,and more than 55%of DEHP(1.0 g kg^-1) in the artificially contaminated soil was removed within 21 d.Furthermore,Rhodococcus sp.strain WJ4 had a strong ability to degrade DEHP without additional nutrients in liquid minimal medium culture and DEHP-contaminated soil and to degrade the homologue of DEHP in both liquid culture and soil.Strain WJ4 represents a novel tool for removing PAEs from contaminated soils and it may have great potential for application in the remediation of environmental pollution by PAEs.     

一株芽孢杆菌属的苄嘧磺隆降解菌的分离鉴定和降解研究

The objectives of this study were to isolate a bensulfuron-methyl (BSM)-degrading strain of Bacillus spp. and to evaluate its effectiveness in remediation of a BSM-contaminated soil. A BSM-degrading bacterium, strain L1, was successfully isolated in this study. Strain L1 was identified as Bacillus megaterium based on its morphological, physiological, and biochemical properties, G+C content, phylogenetic similarity of 16S rDNA, and fatty acid compositions. Two experiments were used to examine BSM degradation by strain L1. When BSM was used as a sole carbon source in a mineral salt medium, the average degradation rate of BSM by strain L1 was 12.8%, which suggested that the strain was able to utilize BSM as a sole carbon and energy source. In addition, supplement of yeast extract (200 mg L-1) significantly (P ≤ 0.01) accelerated the degradation of BSM by strain L1. Almost complete degradation (97.7%) of BSM could be achieved in 84 h with addition of yeast extract. In addition, when a sterile soil was supplemented with BSM (50 mg L-l), BSM degradation rate was 94.3% in 42 d, indicating the potential of using microbes for the remediation of BSM-contaminated soils in fields.     

Isolation and Characterization of a Bensulfuron-Methyl-Degrading Strain L1 of Bacillus

The objectives of this study were to isolate a bensulfuron-methyl (BSM)-degrading strain of Bacillus spp. and to eval-uate its effectiveness in remediation of a BSM-contaminated soil. A BSM-degrading bacterium, strain L1, was successfully isolated in this study. Strain L1 was identified as Bacillus megaterium based on its morphological, physiological, and biochemical properties, G+C content, phylogenetic similarity of 16S rDNA, and fatty acid composition. Two experiments were used to examine BSM degradation by strain L1. When BSM was used as a sole carbon source in a mineral salt medium, the average degradation rate of BSM by strain L1 was 12.8%, which suggested that the strain was able to utilize BSM as a sole carbon and energy source. Supplement of yeast extract (200 mg L-1 ) significantly (P ≤ 0.01) accelerated the degradation of BSM by strain L1. Almost complete degradation (97.7%) of BSM could be achieved in 84 h with addition of yeast extract. In addition, in a sterile soil with 50 mg L-1 BSM, BSM degradation rate by strain L1 was 94.3% in 42 d, indicating the potential of using microbes for the remediation of BSM-contaminated soils in fields.     

Effects of Bacterial-Feeding Nematode Grazing and Tea Saponin Addition on the Enhanced Bioremediation of PyreneContaminated Soil Using Polycyclic Aromatic Hydrocarbon-Degrading Bacterial Strain

As one of the most widely distributed bacterial predators in the soil, the role of bacterivorous nematodes on the enhanced bioremediation of polycyclic aromatic hydrocarbon-contaminated soils is crucial, but remains to be investigated.A microcosm-level study was conducted to examine the effects of bacterial-feeding nematode grazing and tea saponin(TS) addition on bioremediation of a pyrene-contaminated soil enhanced by the polycyclic aromatic hydrocarbon(PAH)-degrading bacterial strain Sphingobium sp.PHE9.After 180 d of incubation, the highest pyrene dissipation(71.3%) was achieved through a combination of Sphingobium sp.PHE9 inoculation with nematode and TS addition.Meanwhile, high counts of culturable PAH-degrading bacteria, soil enzyme activity, and biodiversity indices were observed under the combined treatment, implying that the microbiological function of the contaminated soil was significantly restored.Additionally, the results of Tenax~ extraction with the first-order three-compartment model indicated that rate-limiting factors varied among treatments.The lack of degrading microorganisms was the main rate-limiting factor for the treatments involving TS/nematode addition, and inadequate bioaccessible pyrene was the vital rate-limiting factor in the treatments involving Sphingobium sp.PHE9 inoculation.The proposed combined clean-up strategy proved to be a promising bioremediation technology for aged pyrene-contaminated soils.     

磷改良剂对中度和高度含碳酸盐的菜园土壤中Cd和Pb环境有效性和植物有效性的影响

The behaviour of metals mainly depends on soil p H, carbonate contents and contamination level, which should be considered for the management of contaminated soils. In this study, kitchen garden topsoils(0–25 cm) were sampled from the area around three smelters in France, with different Cd and Pb contamination levels. Effect of a phosphate amendment(a mixture of diammonium phosphate and hydroxyapatite) on the environmental availability and phytoavailability of Cd and Pb was evaluated by different chemical extractions and cultivating lettuce(Lactuca sativa L.), respectively. Changes in the distribution of Cd and Pb were found in most contaminated soils after phosphate amendment. An increase of Cd and Pb in the residual phase was highlighted in almost all carbonated contaminated soils, whereas a decrease of Pb in the exchangeable, water and acid-soluble phase was observed in most contaminated soils with the lowest carbonate contents. The concentrations of extractable Cd and Pb using calcium chloride and acetic and citric acids generally decreased after the soil amendment. Lettuces grown on amended soils were acceptable for human consumption as regard to Pb concentration. In contrast, some lettuces were unacceptable for human consumption, since the concentrations of Cd in the leaves were higher than the European legislation limit. Surprisingly, in carbonated soils with very low concentration of Cd, the Cd concentrations in lettuce reached up to the European legislation limit, making the lettuce unacceptable for human consumption.Our study highlighted the fact that the total metal concentration in soils does not always allow to predict the metal accumulation in the edible parts of vegetables in order to make a judgement about their acceptability or unacceptability for human consumption.     

我国几种土壤中铁锰结核的元素组成和地球化学特点

The objective of this research was to isolate a dichlorvos （2,2-dichlorovinyl dimethyl phosphate）-degrading strain of Ochrobactrum sp., and determine its effectiveness in remediation of a dichlorvos-contaminated soil. A dichlorvos-degrading bacterium （strain DDV-1） was successfully isolated and identified as an Ochrobactrum sp. based on its 16S rDNA sequence analysis. Strain DDV-1 was able to utilize dichlorvos as a sole carbon source, and the optimal pH and temperature for its cell growth and degradation were 7.0 and 30 ℃, respectively. Also, the growth and degradation of strain DDV-1 showed the same response to dissolved oxygen. In addition, the soil degradation test indicated that in soil spiked with 100 mg L^-1 or 500 mg L^-1 dichlorvos and inoculated with 0.5% or 1.0% （v/v） strain DDV-1, complete degradation of dichlorvos could be achieved in 24 h. The present study showed that strain DDV-1 was a fast dichlorvos-degrading bacterium in soil. However, further research will be needed to clarify the degradation pathway and the properties of the key enzymes involved in its biodegradation.     

草坪缓冲带限制斜坡上葡萄园敌草隆向地表水和地下水迁移效果的研究

Trichloroethylene (TCE), as one of the most common chlorinated organic compounds in soils and aquifers at many industrial sites, is carcinogenic and often recalcitrant in environment. TCE degradation in artificially contaminated soil samples was conducted using Fenton-like processes, i.e., by addition of excess hydrogen peroxide (H2O2 ). H 2 O 2 could directly oxidize TCE without addition of ferrous iron in contaminated soil. Under the optimal condition (H2O2 concentration of 300 mg kg 1 , pH at 5.0, and reaction time of 30 min), the removal efficiency of TCE in the soil was up to 92.3%. When the initial TCE concentration increased from 30 to 480 mg kg 1 in soil, the TCE removal rates varied from 89.2% to 86.6%; while the residual TCE in soil ranged from 2.28 to 47.57 mg kg 1 . Results from successive oxidations showed that the TCE removal rate with the TCE concentration of 180 mg kg 1 increased slightly from 91.6% to 96.2% as the number of successive oxidation cycle increased from one to four. Therefore, increasing the frequency of H2O2 oxidation was perhaps a feasible way to increase TCE removal rate for TCE-contaminated soil.     

二氯喹啉酸·苄嘧磺隆复合污染降解菌的特性研究

A bacterial strain, designated as LS, was isolated from a contaminated soil and was found to be capable of utilizing quinclorac, bensulfuronmethyl, and a mixture of the two as carbon and energy sources for growth. Strain LS was identified as Ochrobactrum sp. based on its physiological-biochemical properties, 16S rDNA sequences, and phylogenetic analysis. The extent of degradation of quinclorac and bensulfuronmethyl at initial concentrations of 1.5 and 0.1 g L^-1 was 90% and 67%, respectively, as measured by high performance liquid chromatography （HPLC）. When a herbicide mixture of 0.34 g L^-1 quinclorac and 0.02 g L^-1 bensulfuronmethyl was applied as carbon sources, quinclorac and bensulfuronmethyl were degraded at 95.7% and 67.5%, respectively. It appears that quinclorac is utilized more easily in a mixture than in a single state. The optimal temperature for growth of strain LS was 37 ℃. Strain LS grew well at pH 6 to 9 and had the highest degradation level for quinclorac and bensulfuronmethyl at an initial pH of 7 and 8, respectively. Addition of 0.25 g L^-1 yeast extract could promote the growth and extent of degradation of quinclorac and bensulfuronmethyl by strain LS. Strain LS also showed the capability to degrade other aromatic compounds such as catechol, propisochlor, 4-chloro-2-methylphenoxyacetic acid sodium （MCPA-Na） and imazethapy. The isolate LS shows a huge potential to be used in bioremediation for treating complex herbicide residues.     

Nitrogen Release from Slow-Release Fertilizers in Soils with Different Microbial Activities

Soil microbial activity is recognized as an important factor affecting nitrogen (N) release from slow-release fertilizers. However,studies on the effect of size and activity of soil microflora on fertilizer degradation have provided contrasting results. To date, no clear relationships exist between soil microbial activity and the release of N from slow-release fertilizers. Hence, the aim of this study was to better understand such relationships by determining the release of N from three slow-release fertilizers in soils with different microbial activities. Soils were amended with urea-formaldehyde (UF), isobutylidene diurea (IBDU), and crotonylidene diurea (CDU). Urea, a soluble fertilizer, was used as the control. Fertilized soil samples were placed in a leaching system, and the release of N was determined by measuring ammonium-N and nitrate-N concentrations in leachates during 90 d of incubation. Non-linear regression was used to fit N leaching rate to a first-order model. In all the treated soils, N was released in the order: urea (89%–100%) IBDU (59%–94%) UF (46%–73%) CDU (44%–56%). At the end of incubation, N released from CDU did not differ (P 0.05) among soils. On the contrary, UF and IBDU released significantly lower (P 0.05) amounts of N in the soil with higher microbial activity and lower pH.The rate constant (K_0) for UF was lower (P 0.05) in the soil with lower pH. Taken together, our results indicated that soil microbial size and microbial activity had a marginal effect on fertilizer mineralization.     

蚯蚓与黑麦草相互作用对土壤中荧蒽去除的影响

Earthworms can promote the bioremediation of contaminated soils through enhancing plant growth and microorganism development. The individual and combined effects of earthworms and ryegrass (Lolium multiflorum Lam.) on the removal of fluoranthene from a sandy-loam alluvial soil were investigated in a 70-d microcosm experiment. The experiment was set up in a complete factorial design with treatments in four replicates: without earthworms or ryegrass (control, CK), with earthworms only (E), with ryegrass only (P), and with both earthworms and ryegrass (EP). The residual fluoranthene, microbial biomass C, and polyphenol oxidase activity in the soil changed significantly (P<0.01) with time. In general, the residual concentration of fluoranthene in the soil decreased sharply from 71.8-88.7 to 31.7-37.4 mg kg 1 in 14 d, and then decreased gradually to 19.7-30.5 mg kg 1 on the 70th d. The fluoranthene concentration left in the soil was the least with both earthworms and ryegrass, compared to the other treatments at the end of the experiment. Half-life times of fluoranthene in the E, P, and EP treatments were 17.8%-36.3% smaller than that of CK. More fluoranthene was absorbed by earthworms than ryegrass. However, the total amounts of fluoranthene accumulated in both the ryegrass and earthworms were small, only accounting for 0.01%-1.20% of the lost fluoranthene. Therefore, we assumed that microbial degradation would play a dominant functional role in fluoranthene removal from soil. We found that earthworms significantly increased microbial biomass C and polyphenol oxidase activity (P<0.01) in the presence of ryegrass at the end of the experiment. Furthermore, microbial biomass C and polyphenol oxidase activity were significantly (P<0.05) and negatively related to the residual fluoranthene concentration. This implied that earthworms might promote the removal of fluoranthene from soil via stimulating microbial biomass C and polyphenol oxidase activity.     

Competitiveness of Rhizobium leguminosarum bv. phaseoli strains in relation to environmental stress and plant defense mechanisms

Summary Six Rhizobium leguminosarum bv. phaseoli strains (Ciat 151, Ciat 895, Ciat 899, CE3, H2C, Kim5s) were tested for nodule occupancy in different bean cultivars at two field sites (one fertile, one acid tropical soil) and in the greenhouse. The effects of several environmental factors such as low pH, high temperature, Al and Mn toxicity, iron deficiency, bean tannins, and bean phytoalexins were tested in vitro. Strain Kim5s was competitive under all tested conditions while strains CE3 and H2C had consistently low nodule occupancy levels. Strain Ciat 151 was superior to the other inoculant strains in the acid soil but competed poorly in the fertile soil. Strain Ciat 895 was more competitive in the fertile soil. There was a decline in nodule occupancy for all strains tested from the first trifoliate leaf stage to the pod-filling stage. No plant genotype effect on nodule occupancy was observed. There were significant (P<0.05) plant genotype and location effects, but no significant strain effect on acetylene reduction activity, plant dry weight, and nodule number. The greenhouse experiments confirmed, at least partially, the results from the field trials. In Leonard jars with an acid soil, strains Ciat 151 and Kim5s were amongst the most competitive strains. In coinoculation experiments, Kim5s was the most competitive strain, followed by Ciat 899 and Ciat 895. The competitiveness of a given strain was affected by the coinoculant strain. Tolerance in vitro to low pH, high growth temperature, Al or Mn toxicity, or Fe limitation was not related to competitiveness of the inoculum strains. The sensitivity of the strains towards bean tannins or bean phytoalexins also was not correlated with their competitiveness.     

酸性农田土壤镉污染修复钝化材料筛选研究

[目的]研究0.3 mg kg-1、1.0mg kg-1、1.5 mg kg-1三种不同镉污染水平的酸性农田土壤单一或复配添加海泡石(H)、膨润土(P)、钙镁磷肥(G)、磷矿粉(L)四种钝化剂钝化镉污染的效果.[方法]采用室内培养模拟实验,添加单一纯化剂处理于开始培养后10 d、20 d、30 d,复配添加钝化剂处理于...     

生物炭对铜矿区污染土壤微生物活性及香根草富集铜、镉、铅的影响

矿区土壤易发生重金属污染,是土地资源利用和维护的一大难题。以铜矿区污染土壤为研究对象,按质量比添加0,1%,2%,4%,10% (w/w)的生物炭,进行香根草室内盆栽试验。研究添加生物炭对土壤pH和微生物活性、香根草富集与转运重金属的影响,探明重金属形态含量与生物炭、微生物活性的相关性,旨在为生物炭与香根草联合修复矿区重金属污染土壤提供理论参考。结果表明:生物炭的添加能提高土壤pH,显著提高土壤FDA水解酶、蔗糖酶和脲酶活性,显著促进土壤基础呼吸,但对土壤微生物量碳无显著影响;生物炭的添加使香根草生物量显著增大,降低土壤Cu和Pb的有效态占比,Cd的变化与此相反;添加生物炭促进香根草对Cd和Pb的富集,降低香根草对Cu的富集,减少Cu、Cd和Pb在香根草体内的转运,因此香根草可作为Cu、Cd和Pb的稳定化植物。土壤蔗糖酶活性与香根草叶片Cu、Cd和Pb含量、有效态和残渣态Cu含量呈显著正相关,土壤基础呼吸与叶片Cu、Cd和Pb含量、有效态Cu、Pb含量呈显著负相关,而与有效态Cd含量呈显著正相关。总之,生物炭可减弱矿区土壤重金属对香根草生长的毒害作用,并促进香根草对重金属的富集,两者结合可改善铜矿区污染土壤的理化性质和微生物活性,有利于重金属污染土壤修复,改善土壤质量。     

真菌漆酶氧化蒽的影响因子及其产物毒性研究

The transformation profiles of polycyclic aromatic hydrocarbons （PAHs） by pure laccases from Trametes versicolor and Pycnoporus sanguineus, and the optimal reaction conditions （acetonitrile concentration, pH, temperature and incubation time） were determined. Anthracene was the most transformable PAH by both laccases, followed by benzo[a]pyrene, and benzo[a]anthracene. Laccase-mediator system （LMS） could not only improve the PAH oxidation but also extend the substrate types compared to laccase alone. 5e/0 or 10~ （v/v） of acetonitrile concentration, pH 4, temperature of 40 ~C, and incubation time of 24 h were most favorable for anthracene oxidation by laccase from T. versicolor or P. sanguineus. The gas chromatography-mass spectrometry analysis indicated that 9,10- anthraquinone was the main product of anthracene transformed by laccase from T. versicolor. Microtox test results showed that both anthracene and its laccase-transformation products were not acute toxic compounds, suggesting that laccase-treatment of anthracene would not increase the acute toxicity of contaminated site.     

4种改良剂对铅锌尾矿污染土壤中光叶紫花苕生长及重金属吸收特性的影响

通过盆栽试验研究了铅锌尾矿污染土壤中施用有机肥、石灰、蛭石和白云石等4种改良剂对光叶紫花苕生长发育、叶绿素及重金属Cu、Cd、Pb、Zn积累特性的影响,并分析了施用改良剂后土壤pH和有效态重金属含量的变化。结果表明,与对照相比,不同改良剂及其不同施用水平均能不同程度地提高土壤pH,显著降低土壤各重金属有效态含量,并显著抑制了Cd、Pb向光叶紫花苕地上部转移,降低了重金属在光叶紫花苕植株地上部的积累,改善了光叶紫花苕的生长和发育,光叶紫花苕株高、地上部鲜重和地下部鲜重、叶绿素含量均有不同程度增加,其中株高和地上部鲜重增加达到显著水平。4种改良剂的不同处理水平对光叶紫花苕地下部重金属含量影响均达显著水平。     

湿地松林土壤生化特性和酶活性对模拟硫沉降的响应

以亚热带湿地松人工林为研究对象,通过3种水平(对照CK:pH 6.5;低硫LS:pH 4.5;高硫HS:pH 2.5)的模拟硫沉降控制试验,分析土壤生化特性及酶活性对硫添加的响应。结果表明:(1)硫输入促进了土壤酸化,0—5 cm土层土壤pH在HS处理下显著降低,5—10 cm土层土壤pH在LS和HS处理下显著降低(P0.05);(2)硫输入对土壤有机碳库存在一定影响,土壤总有机碳(TOC)对硫输入无显著响应,但土层间的差异性显著增加(P0.05),土壤可溶性有机碳(DOC)受影响有限,5—10 cm土层微生物量碳(MBC)LS显著降低(P0.05);(3)硫输入对土壤有效氮库影响存在差异,土壤可溶性有机氮(DON)、铵态氮(NH_4~+—N)尚未表现出显著变化,土壤硝态氮(NO_3~-—N)、土壤微生物量氮(MBN)均在HS处理下显著降低,且硫输入加剧土层间的差异性(P0.05);(4)硫输入抑制了酶活性,土壤脲酶活性在HS处理下显著降低(P0.05),土壤蔗糖酶活性无显著变化,但硫输入均弱化了土层间酶活性的差异性。综合分析所有处理下的土壤生化性质和酶活性等指标发现,对硫添加响应敏感的是土壤pH和酶,土层是另外一个主要影响因子,硫添加和土层的交互作用则影响有限。采用Pearson分析得出,硫输入改变了土壤生化特性、酶活性等指标间的相关性程度。可见,酸雨对土壤酸化的影响是一个逐渐累积的过程,外源性硫添加对土壤碳氮及酶活性的影响存在一定差异,这可为硫沉降环境胁迫下森林管理提供科学依据。     

Soil pH,rhizobia, and vesicular-arbuscular mycorrhizae inoculation effects on growth and heavy metal uptake of alfalfa (Medicago sativa L.)

Summary The interaction between soil pH and inoculation with rhizobia and vesicular-arbuscular mycorrhizae (VAM) was studied in an industrially polluted soil contaminated with high levels of Zn and Cd. A silt loam soil (pH 6.7) was amended with Ca(OH)₂ or elemental S to adjust the soil pH to 4.3, 5.3, 6.0, and 7.2. Alfalfa (Medicago sativa L.) was planted in each treated soil an subsequently inoculated with Rhizobium meliloti and/or a mixed VAM spore population. Alfalfa growing in soils at a pH of 4.3 and 5.3 failed to survive as a result of soil acidity and heavy metal toxicity. At the three higher pH values, growth and foliar N and P were significantly increased by inoculation with rhizobia or VAM. The greatest increase was observed when both VAM and rhizobia were inoculated together into the soil. With a soil pH of 6.0 and 6.7, the available heavy metal concentration in the soil was high and the VAM significantly decreased heavy metal uptake from these soils. The foliar concentration of Zn was reduced from 455 to 306 g g^–1 by inoculation with VAM (pH 6.0). At the highest soil pH (7.2), however, available heavy metal concentrations were generally lower and NAM significantly increased the heavy metal uptake. The influence of VAM on heavy metal uptake thus appears to be partly a function of the available heavy metal content in the soil.     

发光酶基因标记荧光假单胞菌X16L2的发光研究

通过光光光度仪和ＡＭＰＮ法定量测定荧光假单胞菌Ｘ１６Ｌ２,在液培和土壤中的发光情况及其数量,发现Ｘ１６Ｌ２在液培和土才壤中的发光动力学曲线相似,达到稳定发光强度的时间均在加入反应底物癸醛后约７分钟。Ｘ１６Ｌ２在液培中的发光强度与生物量吴正相关。土壤中Ｘ１６Ｌ２的发光量既与活菌数有关,也与土壤条件有关,土著微生物对Ｘ１６Ｌ２的光量,土壤中Ｘ１６Ｌ２的发光量既与活菌数有关,也与土壤条件有关。土著微生物