微生物降解多环芳烃的研究进展

多环芳烃(PAHs)是具有严重危害的环境污染物质。介绍PAHs的降解菌,降解机理和PAHs的生物修复方面的研究进展。土壤中PAHs的生物修复被认为是解决污染的有效方法,目前,菲的生物降解途径已经比较清楚,但对结构更为复杂的多环芳烃研究较少。文章还对消除环境中多环芳烃的相关生物技术提出展望。     

Biodegradation of selected UV-irradiated and non-irradiated polycyclic aromatic hydrocarbons (PAHs)

Biodegradation of UV-irradiated anthracene, pyrene,benz[a]anthracene,and dibenz[a,h]anthracene was comparedto that of the non-irradiated samples, individuallyand in synthetic mixtures with enrichment cultures.Combined treatment was repeated for individual anthraceneand for the PAH mixture with Sphingomonas sp.strain EPA 505 and Sphingomonas yanoikuyae.Enrichment culture studies were performed on the PAHmixtures in the presence of the main photoproduct ofanthracene, pure 9,10-anthracenedione. Photochemicallypretreated creosote solutions were also subjected tobiodegradation and the results were compared tothose of the non-irradiated solutions. The primaryinterest was on 16 polycyclic aromatic hydrocarbons(PAHs) listed as priority pollutants by European Union(EU) and the United States Environmental ProtectionAgency (USEPA). Irradiation accelerated thebiodegradation onset for anthracene, pyrene, andbenz[a]anthracene when they were treatedindividually. The biodegradation of irradiatedpyrene started with no lag phase andwas complete by 122 h whereas biodegradation of thenon-irradiated sample had a lag of 280 h andresulted in complete degradation by 720 h. Biodegradation ofPAHs was accelerated in synthetic mixtures, especiallyin the presence of pure 9,10-anthracenedione.In general, irradiation had no effect on the biodegradation of PAHsincubated in synthetic mixtures or with pure cultures. Undercurrent experimental conditions, the UV-irradiation invariablyreduced the biodegradation of PAHs in creosote. Based onthe results of the present and previous photochemical-biologicalstudies of PAHs, the influence of the photochemical pretreatmenton the biodegradation is highly dependent on the compoundsbeing treated and other process parameters.     

厌氧微生物降解多环芳烃研究进展

多环芳烃(PAHs)是一类普遍存在于环境介质中的难降解有机污染物,相对于好氧微生物降解PAHs的研究,厌氧微生物降解PAHs的研究则相对较少.本文从厌氧微生物降解PAHs的研究背景,厌氧降解微生物的特点和不同厌氧降解还原反应体系的角度综述了厌氧微生物降解PAHs的概况;结合厌氧微生物降解萘和菲转化途径的介绍,推断了其降解机制的内在原因;同时通过总结影响厌氧微生物降解PAHs的主要因素(包括:PAHs的生物可利用性、外源营养物质的添加、外源电子受体的添加、特定厌氧降解菌的筛选强化和部分环境因素等),指出了制约降解进程的潜在限制因子;并对厌氧微生物降解PAHs研究目前存在的问题和未来的发展方向作了简述与展望.     

Optimized cultivation of highly-efficient degradation bacterial strains and their degradation ability towards pyrene

Two bacterial strains,Pyl and Py4,have been tamed and isolated through long cultivation with polycyclic aromatic hydrocarbon-pyrene as the single carbon source.It has been proven that they are both highly-efficient pyrene degrading bacteria and both Bacillus sp..The pyrene degradation ability of separated Pyl,Py4 and the consortium of equal Pyl and Py4 was studied in this project.It is shown that pyrene degradation rates were 88% in 10hr by Py1,84% in 14hr by Py4,and 88% in 8hr by the consortium.It was also determined that the best degradation temperatures were 37℃ and pH 7.0 respectively.The influence of different nutrient substrates added in the degradation experiments was also studied.It was shown that sodium salicylate,sodium acetate and yeast exuact had obvious simulative effect,but glucose had no obvious effect.     

Integrated Approach for Polycyclic Aromatic Hydrocarbon Solubilization from the Soil Matrix to Enhance Bioremediation

Polycyclic aromatic hydrocarbons (PAHs) are known to be toxic to living organisms and have been identified as carcinogenic. In this study, a pathway of surfactant flushing, chemical oxidation, and biological treatment is proposed to remediate the soils polluted with the hydrophobic PAHs. Different surfactants such as Tween 80, Brij 35, sodium dodecyl sulfate (SDS), and polyethylene glycol (PEG) 6000 were tested in order to increase the PAH solubilization from the soil matrix. The maximum desorption efficiency of naphthalene and anthracene were found to be 56.5% and 59%, respectively, when Brij and SDS were used. The soluble PAH in the aqueous phase was amended with sodium thiosulfate (3%) to oxidize the PAH into a more bioavailable form. The chemical oxidation with subsequent biodegradation by Pseudomonas aeruginosa exhibited the relatively high PAH degradation rate (1.24 times higher) when compared with chemical oxidation alone. These results display the efficiency of chemical pretreatment of PAH-contaminated soil for improved bioremediation.     

Genotoxicity Assessment of Wood-Preserving Waste-Contaminated Soil Undergoing Bioremediation

Bioremediation represents one of the most cost-effective technologies for treatment of petroleum hydrocarbons in contaminated surface soils. A major concern for regulatory agencies when evaluating bioremediation is how to determine acceptable levels for residual organics in soil. Although guidelines have been developed for some organics in soil, limited information is available to define acceptable levels of the metabolites of biological degradation. The products of oxidative degradation are likely to be more water soluble and may also be more toxic. The purpose of the current study was to monitor changes in compound concentration and genotoxicity in soils undergoing bioremediation. The site selected for this study was a former wood-preserving site in the northwestern United States. Soil samples were collected over a 4-year period from two 6075-m² land treatment units. Conditions for biodegradation were enhanced by the addition of water and nutrients, as well as by frequent tilling to add oxygen. Due to the location of the facility, the temperature was conducive to a more rapid rate of biodegradation for approximately 6 months per year. Soil samples were collected using a grid system and solvent extracted. Polycyclic aromatic hydrocarbons were quantified in soil extracts using gas chromatography-mass spectrometry (GC/MS), and genotoxicity measured using the Salmonella/microsome assay. After 2 years of treatment, concentrations of total and carcinogenic polycyclic aromatic hydrocarbons (PAHs) were reduced to approximately 10% the concentration in the untreated soil. However, the mean weighted activity of the untreated soil was 293 net revertants per g soil, whereas the extracts of soil collected after 2 years induced a mean weighted activity of 325 net revertants per g soil. Thus, although biodegradation clearly reduced the concentration of total and carcinogenic PAHs in the surface soils, the results from the genotoxicity bioassay indicate that there was a lag in the reduction of mutagenicity in treated soils.     

Evaluation of a creosote-based medium for the growth and preparation of a PAH-degrading bacterial community for bioaugmentation

Creosote was evaluated as an inexpensive carbon source for growing inocula of a polycyclic aromatic hydrocarbon (PAH)-degrading bacterial community (community five). Creosote was a poor growth substrate when provided as sole carbon source in a basal salts solution (BSM). Alternatively, peptone, yeast extract or glucose in BSM supported high growth rates, but community five could not subsequently degrade pyrene. A combination of creosote and yeast extract in BSM (CYEM) supported growth and maintained the pyrene-degrading capacity of community five. Optimum pyrene-degrading activity occurred when the inocula were grown in creosote and yeast extract concentrations of 2 ml L⁻¹ and 1 g L⁻¹ respectively: concentrations outside these values resulted in either low biomass yields or loss of PAH-degrading activity. CYEM-grown community five inocula degraded 250 mg L⁻¹ of pyrene in BSM at a rate comparable to cultures inoculated with community five grown in BSM-pyrene. However, the CYEM-grown community showed a 40% lower rate of PAH degradation in a synthetic PAH mixture compared with pyrene-grown cells and there was an increase in the lag period before the onset of PAH degradation. This appears to reflect a weaker induction of PAH catabolism by CYEM compared to BSM-pyrene. Journal of Industrial Microbiology & Biotechnology (2000) 24, 277–284. Received 24 August 1999/ Accepted in revised form 20 January 2000     

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.     

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。     

多环芳烃降解菌的筛选与降解能力测定

从本溪多环芳烃(PAHs)污染土壤中经富集培养筛选出8株PAHs降解菌,研究了8株菌及其等比例混合培养对菲、芘和苯并[a]芘的降解能力。结果表明,在28℃,培养基中菲、芘和苯并[a]芘的浓度分别为50、50和5mg·L-1的复合底物条件下,培养28d后,菌株B3的降解效果最好,对菲、芘和苯并[a]芘的降解率分别为88.4%、54.0%和68.4%,8株菌的混合培养对菲、芘和苯并[a]芘的降解率分别为87.7%、35.3%和42.0%;经生理生化实验和16SrRNA序列比对,初步鉴定B3菌为假单胞菌属(Pseudomonas sp.)。     

微生物降解多环芳烃(PAHs)的研究进展

从多环芳烃(PAHs)的降解菌株的筛选、降解机制以及PAHs污染的生物修复等方面介绍了微生物降解PAHs的最新研究进展。     

Biotransformation of bezo[a]pyrene in bench scale reactor using laccase of Pycnoporus cinnabarinus

The biotransformation of benzo[a]pyrene by purified extracellular laccase of Pycnoporus cinnabarinus was investigated in bench scale reactors. The reaction required the presence of exogenous mediator ABTS. Most of 95% of the substrate was converted within 24 hours. The enzyme preparation oxidised the substrate mainly to benzo[a]pyrene 1,6- 3,6- and 6,12-quinones in a 2/1/1 ratio after 24 h incubation.     

土壤中多环芳烃的微生物降解及土壤细菌种群多样性

利用室内模拟方法,研究中、低浓度多环芳烃(PAHs)污染土壤的微生物修复效果,阐明土壤微生物（接种和土著）与PAHs降解的关系.结果表明:投加PAHs高效降解菌可以促进土壤中PAHs的降解,2周内效果显著;典型PAHs降解的难易程度依据为：菲<蒽<芘<苯并(a)芘和屈;细菌种群丰度和多样性均与PAHs降解呈负相关关系,同一处理细菌种群结构随时间变化不大.对于中、低浓度PAHs原位污染土壤,增强土著菌的活性是提高土壤PAHs降解率的有效途径之一.     

三株降解芘的戈登氏菌鉴定及其降解能力

从沈抚灌区多环芳烃污染土壤中筛选出的芘降解菌D44、D82S和D82Q,经形态观察、生理生化试验和16S rDNA序列分析确定均为戈登氏菌属(Gordonia sp.).3株菌的最适生长pH值均为7,当pH值低于5或高于9时,生长均受到明显抑制.降解试验表明,3株菌能以芘、苯并芘、蒽、萘、菲和荧蒽为唯一碳源和能源生长.经过7 d的培养,3株菌对初始浓度为100 mg.L-1的芘的降解率均在65%以上,对初始浓度为50 mg.L-1的苯并芘的降解率分别为79.6%、91.3%和62.8%.通过PCR检测发现D82Q和D82S含有烷烃单加氧酶基因alkB.     

Fungal metabolism of polycyclic aromatic hydrocarbons: past, present and future applications in bioremediation

This article examines the importance of non-ligninolytic and ligninolytic fungi in the bioremediation of polycyclic aromatic hydrocarbon contaminated wastes. The research from the initial studies in Dave Gibson’s laboratory to the present are discussed. Received 10 August 1997/ Accepted in revised form 15 August 1997     

Physiological characterization of Mycobacterium sp. strain 1B isolated from a bacterial culture able to degrade high-molecular-weight polycyclic aromatic hydrocarbons

AIM: The aim of this study was to further characterize a bacterial culture (VUN 10,010) capable of benzo[a]pyrene cometabolism. METHODS AND RESULTS: The bacterial culture, previously characterized as a pure culture of Stenotrophomonas maltophilia (VUN 10,010), was found to also contain another bacterial species (Mycobacterium sp. strain 1B), capable of degrading a similar range of PAH substrates. Analysis of its 16S rRNA gene sequence and growth characteristics revealed the strain to be a fast-growing Mycobacterium sp., closely related to other previously isolated PAH and xenobiotic-degrading mycobacterial strains. Comparison of the PAH-degrading characteristics of Mycobacterium sp. strain 1B with those of S. maltophilia indicated some similarities (ability to degrade phenanthrene and pyrene), but some differences were also noted (S. maltophilia able to degrade fluorene, but not fluoranthene, whereas Mycobacterium sp. strain 1B can degrade fluoranthene, but not fluorene). Unlike the S. maltophilia culture, there was no evidence of benzo[a]pyrene degradation by Mycobacterium sp. strain 1B, even in the presence of other PAHs (ie pyrene) as co-metabolic substrates. Growth of Mycobacterium sp. strain 1B on other organic carbon sources was also limited compared with the S. maltophilia culture. CONCLUSIONS: This study isolated a Mycobacterium strain from a bacterial culture capable of benzo[a]pyrene cometabolism. The Mycobacterium strain displays different PAH-degrading characteristics to those described previously for the PAH-degrading bacterial culture. It is unclear what role the two bacterial strains play in benzo[a]pyrene cometabolism, as the Mycobacterium strain does not appear to have endogenous benzo[a]pyrene degrading ability. SIGNIFICANCE AND IMPACT OF THE STUDY: This study describes the isolation and characterization of a novel PAH-degrading Mycobacterium strain from a PAH-degrading culture. Further studies utilizing this strain alone, and in combination with other members of the consortium, will provide insight into the diverse roles different bacteria may play in PAH degradation in mixed cultures and in the environment.     

Fate of polycyclic aromatic hydrocarbons (PAH) in the rhizosphere and mycorrhizosphere of ryegrass

Polycyclic aromatic hydrocarbons (PAH) can be degraded in the rhizosphere but may also interact with vegetation by accumulation in plant tissues or adsorption on root surface. Previous studies have shown that arbuscular mycorrhizal (AM) fungi contribute to the establishment and maintenance of plants in a PAH contaminated soil. We investigated the fate of PAH in the rhizosphere and mycorrhizosphere including biodegradation, uptake and adsorption. Experiments were conducted with ryegrass inoculated or not with Glomus mosseae P2 (BEG 69) and cultivated in pots filled with soil spiked with 5 g kg⁻¹ of anthracene or with 1 g kg⁻¹ of a mixture of 8 PAH in a growth chamber. PAH were extracted from root surfaces, root and shoot tissue and rhizosphere soil and were analysed by GC-MS. In both experiments, 0.006 – 0.11‰ of the initial extractable PAH concentration were adsorbed to roots, 0.003 – 0.16‰ were found in root tissue, 0.001‰ in shoot tissue and 36 – 66% were dissipated, suggesting that the major part of PAH dissipation in rhizosphere soil was due to biodegradation or biotransformation. With mycorrhizal plants, anthracene and PAH were less adsorbed to roots and shoot tissue concentrations were lower than with non mycorrhizal plants, which could contribute to explain the beneficial effect of AM fungi on plant survival in PAH contaminated soils. This revised version was published online in June 2006 with corrections to the Cover Date.     

Degradation of polycyclic aromatic hydrocarbons and long chain alkanes at 6070 °C by Thermus and Bacillus spp

Although polycyclic aromatic hydrocarbons (PAH) and alkanesare biodegradable at ambient temperature, in some cases low bioavailabilities are thereason for slow biodegradation. Considerably higher mass transfer rates and PAH solubilities and hence bioavailabilities can be obtained at higher temperatures. Mixed and pure cultures of aerobic, extreme thermophilic microorganisms (Bacillus spp., Thermus sp.) were used to degrade PAH compounds and PAH/alkane mixtures at 65 °C. The microorganismsused grew on hydrocarbons as sole carbon and energy source. Optimal growthtemperatures were in the range of 60–70 °C at pH values of 6–7. The conversion of PAH with 3–5 rings (acenaphthene, fluoranthene, pyrene, benzo[e]pyrene) was demonstrated. Efficient PAH biodegradation required a second, degradable liquid phase. Thermus brockii Hamburg metabolized up to 40 mg (l h)^-1 pyrene and 1000 mg(1 h)^-1 hexadecane at 70 °C. Specific growth rates of 0.43 h^-1 were measured for this strain with hexadecane/pyrene mixtures as the sole carbon and energy source in a 2-liter stirred bioreactor. About 0.7 g cell dry weight were formed from 1 g hydrocarbon. The experiments demonstrate the feasibility and efficiency of extreme thermophilic PAH and alkane biodegradation.