菲污染土壤的微生物修复机制

菲(Phenanthrene)是存在于煤焦油中,含三个苯环的稠环芳烃。除了具有"三致"作用外,菲稳定的化学结构和高辛醇-水分配系数等特性,使其具备较强的抗降解能力,易在环境中富集,破坏土壤微生态结构,降低农作物品质,威胁人类健康。而且随着化石燃料的长期大量使用,受菲污染的土地面积也急速增加,给人类的健康及生产活动带来极大的威胁。因此,有效清除土壤中菲及其他多环芳烃污染物,净化环境,具有重要的现实意义。微生物降解作为治理菲污染的方法之一,具有高效、低成本、环境友好的特点,受到研究者的高度重视。本文从菲降解菌的种类、降解机理、分子机制、影响修复等因素及微生物与植物联合修复五个方面进行综述,为进一步利用环境微生物,开发高效菲降解菌,治理菲污染提供参考。     

Comparison of Photocatalytic Oxidation and Ozonation in Degrading of Polycyclic Aromatic Hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs) are hazardous pollutants. Photocatalytic oxidation (PCO) was used to degrade individual PAHs dissolved in aqueous solution and results were compared to those used for ozonation treatment of PAHs in aqueous phase and adsorbed on soil reported previously. Both PCO and ozonation showed high effectiveness and efficiency in degrading PAHs within only minutes of time. Ozonation showed higher performance in the degradation of PAHs in aqueous solution than in soil, whereas the treatment efficiency of PCO was higher than that of ozonation in degrading PAHs in aqueous solution. Both methods have advantages over each other but they have their own limitation(s) in practical application.     

Pyrene and Phenanthrene Influence on Soil Microbial Populations

Two studies were conducted to evaluate microbial populations in polycyclic aromatic hydrocarbon-contaminated soil. Captina silt loam was freshly exposed to (1) 0 or 2000?mg pyrene/kg and sampled after 10- and 61-wk incubation and (2) 0 or 505?mg pyrene + 445?mg phenanthrene/kg and sampled after a 21-wk incubation. Microbial numbers were determined by plate-count techniques. Isolated bacteria, selected degraders, and wholesoil extracts were analyzed by fatty acid methyl ester analysis (FAME). In the pyrene experiment, pyrene did not affect total bacterial or fungal numbers, but pyrene degraders increased from undetectable levels to 7.09 log₁₀ degraders/g in the contaminated soil. The FAME analysis of bacterial isolates detected no pyrene effect, but wholesoil FAME indicated an increase in the contaminated soil of a fatty acid characteristic of protozoa and a major fatty acid detected in isolated degraders. In the pyrene + phenanthrene experiment, the contaminants had no impact on bacterial, fungal, or actinomycete numbers but increased degrader numbers. No effect of pyrene + phenanthrene was detected by isolate FAME, but whole-soil FAME indicated an effect similar to that in the pyrene experiment. The results indicate that pyrene, although not impacting microbial numbers, may have altered the soil microbial composition and that Captina silt loam can develop an effective degrader population under tested conditions.     

Degradation of straight-chain aliphatic and high-molecular-weight polycyclic aromatic hydrocarbons by a strain of Mycobacterium austroafricanum

AIMS: Our goal was to characterize a newly isolated strain of Mycobacterium austroafricanum, obtained from manufactured gas plant (MGP) site soil and designated GTI-23, with respect to its ability to degrade polycyclic aromatic hydrocarbons (PAHs). METHODS AND RESULTS: GTI-23 is capable of growth on phenanthrene, fluoranthene, or pyrene as a sole source of carbon and energy; it also extensively mineralizes the latter two in liquid culture and is capable of extensive degradation of fluorene and benzo[a]pyrene, although this does not lead in either of these cases to mineralization. Supplementation of benzo[a]pyrene-containing cultures with phenanthrene had no significant effect on benzo[a]pyrene degradation; however, this process was substantially inhibited by the addition of pyrene. Extensive and rapid mineralization of pyrene by GTI-23 was also observed in pyrene-amended soil. CONCLUSIONS: Strain GTI-23 shows considerable ability to mineralize a range of polycyclic aromatic hydrocarbons, both in liquid and soil environments. In this regard, GTI-23 differs markedly from the type strain of Myco. austroafricanum (ATCC 33464); the latter isolate displayed no (or very limited) mineralization of any tested PAH (phenanthrene, fluoranthene or pyrene). When grown in liquid culture, GTI-23 was also found to be capable of growing on and mineralizing two aliphatic hydrocarbons (dodecane and hexadecane). SIGNIFICANCE AND IMPACT OF THE STUDY: These findings indicate that this isolate of Myco. austroafricanum may be useful for bioremediation of soils contaminated with complex mixtures of aromatic and aliphatic hydrocarbons.     

Effects of Fungal Bioaugmentation and Cyclodextrin Amendment on Fluorene Degradation in Soil Slurry

This study assesses the potential of fungal bioaugmentation and the effect of maltosyl-cyclodextrin amendment, as an approach to accelerate fluorene biodegradation in soil slurries. 47 fungal strains isolated from a contaminated site were tested in the biodegradation of fluorene. Results showed the greater efficiency of "adaptated" fungi isolated from contaminated soil vs. reference strains belonging to the collection of the laboratory. These assays allowed us to select the most efficient strain, Absidia cylindrospora, which was used in a bioaugmentation process. In the presence of Absidia cylindrospora, more than 90% of the fluorene was removed in 288 h while 576 h were necessary in the absence of fungal bioaugmentation. Maltosyl-cyclodextrin, a branched-cyclodextrin was chosen in order to optimize fluorene bioavailability and biodegradation in soil slurries. The results of this study indicate that Absidia cylindrospora and maltosyl-cyclodextrin could be used successfully in bioremediation systems.     

多环芳烃污染土壤微生物修复研究进展

多环芳烃是我国土壤环境质量标准中要求严格管控的一类持久性有机污染物,利用微生物技术修复有机污染土壤具有绿色、经济等突出特点,应用前景广泛。目前多学科的协同发展和新技术的研究应用,为多环芳烃土壤微生物转化机制与污染生态过程等方面带来了新的认识,同时对修复技术的实际应用与调控提供了新的思考方向。本文以多环芳烃污染土壤微生物修复为主体,从污染土壤微生物修复应用技术、多环芳烃微生物降解特征、土壤体系污染物归趋规律与微生物作用及土壤污染微生物群落响应与研究技术等方面进行综合评述,并针对现存应用技术瓶颈和理论空白作进一步思考和展望。     

Optimization of PAHs Oxidation from a Concentrate of Soil Attrition Using Potassium Permanganate

The treatment of soils contaminated with organic compounds, such as polycyclic aromatic hydrocarbons (PAHs), by attrition produced large amounts of highly concentrated attrition sludge (PAH – attrition concentrate – PAC). This paper studied the performance of an oxidation process using potassium permanganate (KMnO₄) to degrade PAHs that were initially present in attrition concentrates. The influence of operating conditions (temperature, concentration of KMnO₄ and reaction time) was studied, and these parameters were optimized using a response surface methodology (RSM). The results showed that the temperature and the reaction time had a significant and positive effect on the degradation of PAHs for the experimental domain studied (temperature between 20 and 60°C and reaction time between 1 and 7 h). The interaction between the temperature and the concentration of KMnO₄ significantly influenced the degradation of the PAHs. The temperature and the concentration of KMnO₄ were the main parameters that influenced the degradation of both phenanthrene (Phe) and benzo [a] pyrene (BaP). For benzo [a] anthracene (BaA), the temperature was the most influential factor. According to our results, the optimal conditions were defined as [KMnO₄] = 0.4 M for 5.5 h at 60°C. These optimal conditions led to degradations of 42.9%, 40.8%, 41.0% and 46.0% of the total PAHs, Phe, BaA and BaP, respectively.     

Impacts of ISCO Persulfate,Peroxide and Permanganate Oxidants on Soils: Soil Oxidant Demand and Soil Properties

The consumption of in-situ chemical oxidation (ISCO) oxidant by soil oxidizable matter (OM), termed the soil oxidant demand (SOD), is an essential factor when designing treatments for successful remediation at an ISCO site. This study aims to assess the impact of different oxidants on SOD and the soil itself, using the Taguchi experimental design. Five oxidation systems, including persulfate (PS), hydrogen peroxide (HP), permanganate (PM), Fe²⁺ activated PS and Fe²⁺ activated HP, and four factors including oxidant concentration, activator concentration, reaction time, and pH were investigated. The results of the Taguchi analysis in this study show that oxidant concentration had the greatest effect on the SOD. Other factors also affected the SOD and the optimum conditions for achieving a lower SOD were determined using the Taguchi design method. Additionally, original and oxidized soils were analyzed using a scanning electron microscope equipped with an X-ray energy dispersive spectrometer to determine the surface morphology and chemical composition of the samples. Variations in soil organic carbon levels and total soil bacterial counts were recorded and the speciation of soil minerals (Fe, Mn, Cu, and Zn) was analyzed.     

Biodegradation of PAHs in Aggregates of a Low Permeability Soil

In the bioremediation of low-permeability soils, pollutant and, especially, the oxygen bioavailability are often the rate limiting steps. In cases when a biopile treatment can represent an applicable technique, pretreatment of the excavated soil is often necessary to attain an adequate air-filled porosity in the soil and to avoid the presence of large soil aggregates. The present work was performed to evaluate the influence of soil aggregate size in the bioremediation of a silt-clay type soil contaminated by PAHs. Microcosms were arranged with spherical soil aggregates of different diameter in near water-saturation conditions. Concentration of two and three aromatic ring PAHs, total biom-ass, and respiration rates were monitored. PAH concentration profiles inside the particles were also obtained. A simple and quick way to estimate the critical dimension of the soil aggregates was developed based on the evaluation of an oxygen penetration depth, that is, the distance from the external surface to the aggregate core beyond which oxygen concentration is practically zero. A very different time course of PAHs consumption was found in the external layer and the inner core of the aggregates as well as in aggregates of different dimensions. The results suggest that only the 3 mm external layer of the sphere is not limited by oxygen diffusion.     

Biodegradation of polycyclic aromatic hydrocarbons in soil around Mathura oil refinery,India

Six polycyclic aromatic hydrocarbons [naphthalene, anthracene, phenanthrene, pyrene, chrysene and benzo(a)-pyrene] were detected in soil receiving effluents from an oil refinery. Biodegradation studies revealed a time-dependent disappearance of these polycyclic aromatic hydrocarbons when they were added to soil samples: naphthalene disappeared completely in 60 days, whereas phenanthrene, anthracene, pyrene, chrysene and benzo(a)pyrene decreased by 87%, 34%, 21%, 5% and 40%, respectively, in 120 days.B.T. Ashok and J. Musarrat were and S. Saxena is with the Interdisciplinary Biotechnology Unit, A.M.U., Aligarh-202002, Uttar Pradesh, India. K.P. Singh is with the Environmental Chemistry Section, Industrial Toxicology Research Centre, M.G. Road, Lucknow-226001, Uttar Pradesh, India. B.T. Ashok is now with the Department of Biochemistry, J.N. Medical College, A.M.U., Aligarh-202002, Uttar Pradesh, India. J. Musarrat is now with the Department of Radiology and Blochemistry Program. The Ohio State University, Columbus, OH 43210, USA.     

一株多环芳烃降解菌及其在多种强化体系中降解菲的潜力

多环芳烃是一类普遍的环境污染物,因其潜在的环境暴露和对人类健康的危害而备受关注。从石化品污染土壤样品中分离到一株以菲为唯一碳源和能源的中温菌 (15–37 ℃,最佳30 ℃) 菌株CFP312。经菌落和菌体形态观察、生理生化测试和16S rRNA同源性分析鉴定属于莫拉氏菌Moraxella sp.。这是Moraxella属中多环芳烃降解菌种的首次报道。研究表明,当菲浓度为400 mg/L时,在48 h和60 h时,菲的去除率分别为84%和90%,降解速率达到1.21、1.29 mg/(L·h)。在菲的降解过程中,检测到3,4-二氢-3,4-二羟基菲为中间产物。据此推断降解菌通过在菲的3,4位进行双加氧完成其生物降解的第一个关键步骤。在水-有机溶剂两相分配体系、胶束水溶液体系和浊点体系中检测了降解菌对不同的菲强化降解体系的适应性。结果表明,降解菌对不同降解体系都表现出了良好的适应性。另外,降解菌可在泥浆-水体系中快速降解污染土壤中的多环芳烃菲,表明其在环境修复方面具有很大的应用潜力。     

Biodegradation of phenanthrene by the indigenous microbial biomass in a zinc amended soil

AIMS: To study the effect of zinc on the biodegradation of phenanthrene by the microbial biomass in soil. METHODS AND RESULTS: Uncontaminated soil was amended with zinc and phenanthrene as single or co-contaminants, and microbial metabolic activity was measured using an intracellular dehydrogenase enzyme bioassay over 37 days. Contaminants were amended at optimum, action and double the action level specified in 'The New Dutch List' (Ministry of Housing, Spatial Planning and Environment, the Netherlands, 2000). Microbial activity in soils with zinc or phenanthrene alone indicated the presence of tolerant, albeit inhibited soil micro-organisms. A zinc concentration at the optimum level of 140 mg kg(-1) in the co-contaminated soil (phenanthrene at 40 mg kg(-1)) resulted in marginal stimulation of the rate of phenanthrene biodegradation. However, Zn2+ concentrations at the action and double the action level of zinc (720 and 1440 mg kg(-1)) inhibited phenanthrene degradation. CONCLUSIONS: Biodegradation of phenanthrene in soils co-contaminated with zinc at concentrations above the action value is impeded. SIGNIFICANCE AND IMPACT OF THE STUDY: Bioremediation efforts to remove polycyclic aromatic hydrocarbon in zinc co-contaminated soils are likely to be constrained.     

Mechanisms of inhibitory effects of polycyclic aromatic hydrocarbons in photosynthetic primary processes in pea leaves and thylakoid preparations

• Inhibitory effects of polycyclic aromatic hydrocarbons (PAHs) on plants were studied in pea leaves in order to elucidate the mechanisms of action of PAHs such as naphthalene (Naph) and phenanthrene (Phen) on activity of photosystem II (PSII).
• The changes in different Chl fluorescence parameters were calculated on the basis of Chl fluorescence induction curves. H₂O₂ content was measured in leaf homogenates with the luminol‐dependent chemiluminescence method.
• We demonstrated that following PAH treatment, total energy dissipation (DI₀/ABS) and amount of Q_B‐non‐reducing complexes of PSII significantly increased. Non‐photochemical quenching (NPQ) also increased, when weak oxidative stress after PAH application developed. In leaves, a two‐step increase in H₂O₂ was found with time of incubation in the presence of PAHs, which may be associated with damage to the lipid bilayer of the plasma membrane and then violation of lipid bilayer membranes of cell organelles.
• A hypothesis for the mode of action of PAHs is provided that involves the role of ROS, membrane permeability and associated functional changes in PSII.

     

沿阶草(Ophiopogon japanicus)对土壤中菲芘的修复作用

采用盆栽试验法,研究沿阶草对土壤中芘、菲的去除效果与修复机制.结果显示:在试验浓度范围(0～322mg · kg-1)内,植物-微生物系统对芘、菲的去除效果明显.种植沿阶草60d后,菲、芘去除率分别为77.58%～96.3%、65.25%～83.25%;平均去除率分别比对照1(加0.1%NaN3)高82.27%、72.73%,比对照2(无NaN3)高43.26%、46.27%.沿阶草能吸收积累土壤中的菲和芘,根部和茎叶部菲、芘含量随土壤中菲、芘浓度的提高而增大;生物浓缩系数随土壤中菲、芘含量的增加而减小,且根部大于茎叶部、芘大于菲.修复过程中,非生物因子、植物积累、植物代谢对菲、芘的去除率分别为6.61%、0.157%、6.54%和3.18%、1.21%、5.72%;微生物降解、植物-微生物间的交互作用对菲、芘的去除率分别为39.01%、26.47%和36.57%、39.34%.说明植物-微生物交互作用、微生物降解作用是土壤中菲、芘去除的主要原因.     

Some Physiological,Microbial, and Toxicological Aspects of the Removal of Phenanthrene by Hydroponic Cultures of Alfalfa (Medicago sativa L.)

Alfalfa (Medicago sativa L.) and other plants bearing an important root system have been shown to be effective in the removal of organic compounds, including polycyclic aromatic hydrocarbons (PAHs). Phenanthrene is one of the main contaminants arising from the petrochemical industry and is included in the USEPA's list of priority toxic pollutants. Hydroponic cultures of alfalfa were employed as a model system to evaluate their capability of removing phenanthrene and to study the plant-pollutant interaction without the interference of a soil matrix. The removal of phenanthrene was followed over a period of 30 days. The half-life of phenanthrene in hydroponics (initial concentration 50 mg L^-1) was reduced 2.7 times when plants were present. Growth index, chlorophyll content of leaves, and peroxidase activity of the roots of plants exposed to phenanthrene were lower than the corresponding values of nonexposed plants. Phenanthrene produced an acute negative effect on the total bacterial counts but also caused an increase in degraders/total bacteria ratio. The Ames Salmonella plate incorporation assay was employed to screen for potential genotoxic metabolites, which could be generated by metabolic activation of the parent compound. None of the samples exhibited a positive response. While lack of a positive response to this test is not a definitive evidence of the absence of genotoxic substances, these results suggest that the plant-assisted removal of phenanthrene merits further investigation.     

Phenanthrene biodegradation and the interaction of <Emphasis Type="Italic">Pseudomonas putida</Emphasis> BS3701 and <Emphasis Type="Italic">Burkholderia</Emphasis> sp. BS3702 in plant rhizosphere

The interaction between the strains degrading polycyclic aromatic hydrocarbons, Pseudomonas putida BS3701 and Burkholderia sp. BS3702, was studied in the course of phenanthrene degradation in plant rhizosphere. Strain BS3702 was shown to accumulate 1-hydroxy-2-naphthoic acid (which is toxic for plants); it was then utilized by strain BS3701, which thereby increased the resistance of plants to the pollutant and to the toxic intermediate. With this type of interaction (cooperation), the efficiency of phenanthrene degradation was noted to decrease.     

Treatability Testing for Weathered Hydrocarbons in Soils: Bioremediation,Soil Washing,Chemical Oxidation,and Thermal Desorption

Soils previously treated with landfarming to reduce petroleum hydrocarbon concentrations are often left with a less biodegradable residual fraction that can present challenges for additional treatment. Four possible polishing technologies were tested on the bench scale for weathered hydrocarbons present in fine-grain soils obtained from a previously landfarmed area at an active oil refinery. The technologies included additional bioremediation (both biostimulation and bioaugmentation tested), soil washing, chemical oxidation, and low-temperature thermal desorption. Multiple parameters were tested separately for each technology to identify possible factors that were relevant across technologies. Extractable hydrocarbons comprised only approximately 35% of the organic carbon in the soils, and this component was considerably less affected by biological, surfactant, and oxidant treatment than organic materials that are not quantified by the TEH analysis. Treatment testing of thermal desorption indicated removal of large quantities of extractable hydrocarbons despite the presence of high organic matter. The additional demand to the system would likely result in considerably large timeframes (biological treatment), reagent quantities (soil washing and oxidation), or energy input (thermal desorption) for treatment of target hydrocarbons on a full scale.     

植物对水中菲和芘的吸收

以菲和芘为多环芳烃（PAHs）代表物,采用水培体系研究了黑麦草（Lolium multiflorum Lam）对水中PAHs的吸收作用,重点研究了植物吸收菲和芘的时间动态.水中菲和芘起始浓度分别为1.00mg/L和0.12mg/L.0～288h内,黑麦草根和茎叶中菲和芘含量均先快速增加而后降低,积累量不断增大,植物根系和茎叶富集系数则先快速升高而后趋于稳定.茎叶中菲和芘含量、茎叶对菲和芘的富集系数比根低1～3数量级,积累量也明显小于根系.黑麦草根系对水中芘有更强的富集能力,其根系富集系数比菲大85%～179%;而其茎叶对菲的富集作用则略强.菲和芘在植物体内有明显的传导作用.0～288h,传导系数（TF）先显著升高而后趋于恒定;但实验条件下,菲和芘的TF值均很小,分别不高于0.031和0.009,且芘的TF值明显小于菲,表明供试植物对芘的传导能力更弱.     

不同介质中多环芳烃光降解及与生物耦合降解研究现状

多环芳烃(PAHs)是环境中广泛存在的一类有机污染物。它的降解一直是人们关注的课题。光降解就是多环芳烃降解的一种重要形式。对在气相、液相和固相不同介质中的PAHs光降解研究进行了综合论述,重点对PAHs在液相介质的降解速率及影响因素、中间产物及降解机制和反应动力学进行了深入探讨,并介绍了光-生物耦合降解多环芳烃的研究进展。建立系统而有效的PAHs光降解研究技术与方法,是目前当务之急。进一步完善PAHs光降解研究的技术与方法,可更准确地研究PAHs光降解机制及影响因素。