多环芳烃污染生物修复研究进展

多环芳烃(polycyclic aromatic hydrocarbon,PAHs)是一类对环境有严重危害的持久性有机污染物。具有高生物富集性、致癌性、致毒性和难降解性,修复治理PAHs污染环境备受国内外政府及学者的关注。目前主要采用物理、化学以及生物方法对多环芳烃污染的土壤和水体进行修复。其中生物修复是一种高效、经济和生态可承受的环保技术,具有成本低、无二次污染等优点。本文从植物修复、微生物修复以及植物-微生物联合修复方面,阐述了国内外生物修复PAHs污染的最新研究进展。指出了生物修复PAHs污染环境需要进一步解决的问题,并对未来发展趋势进行了展望。     

多环芳烃污染土壤生物修复研究进展

多环芳烃 (Polycyclic aromatic hydrocarbons,PAHs) 是一类广泛分布于环境中的持久性污染物,结构稳定、难以降解,对生态环境和生物具有“三致”毒害性,其环境去除和修复备受关注。绿色、安全、经济的生物修复技术被广泛应用于PAHs污染土壤的修复。本文从土壤中PAHs的来源、迁移、归趋和污染水平总结了目前我国土壤多环芳烃污染的基本状况;归纳了具有PAHs降解作用的微生物、植物种类及机理;比较了微生物修复、植物修复和联合修复3类主要的生物修复技术。指出植物与微生物的互作机理的解析,抗逆菌株、植株的筛选与培育,实际应用的安全和效能评估应成为多环芳烃污染土壤修复领域未来的研究方向。     

生物泥浆反应器中多环芳烃微生物降解调控因子研究

多环芳烃 (PAHs)是一类普遍存在的环境中的优先有机污染物 ,在土壤中残留持久并难以降解 ,因此给环境和人体健康带来潜在危胁 [5] 。研究表明 ,微生物降解是去除 PAHs的主要途径 [6]。微生物能够以利用 PAHs作为碳源与能源和共代谢两种方式降解 PAHs[7] 。泥浆反应器作为生物修复技术之一 ,具有处理周期短 ,降解条件易于控制和处理效果好的特点[8,9] ,目前已成为一种重要的处理技术 ,在欧、美等发达国家 ,受到广泛重视。Grosser[10 ]等人发现 ,把微生物从污染地区分离培养后 ,接种到污染土壤中可大大提高芘的降解率。泥浆反应器中污染…     

高环多环芳烃降解菌的筛选及其降解特性

通过富集培养及平板升华法从本溪钢铁公司周边多环芳烃(PAHs)污染土壤中分离出7株PAHs降解菌。以芘和苯并[a]芘为底物进行摇瓶降解实验,结果表明:G1、G2和G3菌株对高环PAHs芘和苯并[a]芘均具有较强的降解能力。进一步研究此3株菌及混合菌对原状污染土壤中PAHs的降解能力,发现80 d时对总PAHs的降解顺序依次为:混合菌G2G1G3,其中混合菌对PAHs降解率较单菌分别提高了9.17%、11.49%和16.11%;4个处理对4~6环PAHs的降解率较对照组相比提高的倍数随着环数增加而增大;总PAHs的降解率与脱氢酶的活性呈正相关。电场影响G1、G2和G3菌株对PAHs降解,在1.0 V·cm~(-1)电场条件下,4环、5环及6环PAHs降解率较单纯微生物修复提高12.13%、13.35%和14.52%,说明3株菌具有较强的电场适应能力,可在高环PAHs污染土壤的电动-微生物修复中应用。形态学观察及16S rRNA序列比对分析表明,G1、G2、G3菌株分别为鞘氨醇单胞菌属(Sphingomonas sp.)、苍白杆菌属(Ochrobactrum sp.)和无色杆菌属(Achromobacter sp.)。     

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。     

多环芳烃在土壤中的行为

多环芳烃（PAHs)在土壤中达到吸附平衡时存在“快”和“慢”两个吸附过程,植物能够从土壤中吸收低分子量的PAHs并向植物的地上部分迁移转化,但PAHs在植物体内主要的累积方式是植物地上部分的空气污染,微生物对PAHs的降解依然是去除PAHs的主要方式,主要通过微生物产生的酶的作用,本文详细分析了影响PAHs生物去除的各种因素。     

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。     

水体沉积物中微生物厌氧呼吸耦合多环芳烃降解的研究进展

多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)是一种具有致癌、致畸、致突变的持久性有机污染物。本文在分析国内外主要水体沉积物中PAHs污染状况的基础上,综述了近几年有关厌氧水体沉积物中微生物以硝酸盐、Fe(III)以及硫酸盐为电子受体进行呼吸耦合PAHs降解的研究概况。此外,还总结了基于微生物的PAHs降解基因组、蛋白质组、代谢组以及菌群水平上互作网络的研究进展,以期为进一步加速PAHs污染水体沉积物原位生物修复提供科学理论参考。     

一株高浓度多环芳烃降解菌的鉴定和降解特性

采用选择性富集培养方法,从沈抚灌区土壤中分离得到多环芳烃(PAHs)高效降解菌NI2,应用此降解菌制备固定化菌剂,修复焦化厂内高浓度PAHs污染土壤,并通过生理生化和16S rDNA测序进行微生物鉴定.经过30 d的降解实验,菌N12对污染土壤中各PAH的去除率＞66％,总去除率为80％.生理生化和16S rDNA测序分析表明,分离得到的菌株N12为分支杆菌属(Mycobacterium sp.),该菌具有与其他分枝杆菌同源的双加氧酶基因nidA和pdoA2.结果表明,从土壤中筛选获得的分枝杆菌可以修复高浓度PAHs污染工业土壤.     

土壤中高分子量PAHs微生物降解机理及影响因素研究进展

高分子量多环芳烃( HMW PAHs)分子结构复杂,疏水性强,是环境中广泛存在的难降解的有机污染物.微生物降解是去除HMW PAHs的主要途径.本文介绍了PAHs降解菌株的种类和降解机理,以及不同环境因子(营养元素、pH值、土壤结构、通气状况和复合污染)对HMW PAHs降解的影响,提出HMW PAHs污染土壤的进一步研究的方向与重点,旨在为HMW PAHs污染修复研究和微生物降解机理研究提供参考.     

Revealing potential functions of VBNC bacteria in polycyclic aromatic hydrocarbons biodegradation

The bioremediation of polycyclic aromatic hydrocarbon (PAH)‐contaminated sites is not running smoothly, because of the lower activity of PAH‐degrading bacteria in actual bioremediation applications. The phenomenon of “viable but nonculturable” (VBNC) state may be a main limiting factor for their poor biodegradation capabilities of PAHs. Due to their abilities of entering into the VBNC state, most of bacterial populations with PAH‐degradation potential remain unculturable. Resuscitation of VBNC bacteria will enhance the degradation capability of indigenous bacteria which will eventually obtain their better capabilities in environmental bioremediation. Although evidences have been presented indicating that resuscitation of VBNC bacteria in polychlorinated biphenyl (PCB)‐contaminated environments not only significantly enhanced PCB degradation, but also obtained novel highly efficient PCB‐degrading bacteria, scanty information is available on the VBNC bacteria in PAH‐contaminated sites. VBNC bacteria, as a vast majority of potential microbial resource could be the repository of novel highly efficient PAH‐biodegraders. Therefore, studies need to be done on resuscitation of VBNC bacteria to overcome key bottlenecks in bioremediation of PAH‐contaminated sites. This mini‐review provides a new insight into the potential functions of VBNC bacteria in PAHs biodegradation.

Significance and Impact of the Study

As the vast majority microbial resource, viable but nonculturable (VBNC) bacteria, which showed their potential functions in polycyclic aromatic hydrocarbons (PAHs) biodegradation, can be of great significance in environmental bioremediation. It is therefore important to resuscitate VBNC bacteria for their better capabilities. Meanwhile, preventing the indigenous functional community from entering into the VBNC state will also maintain the high activity of PAH‐degrading bacteria in actual bioremediation applications. Undoubtedly, much more work needs to be done to reveal indigenous micro‐organisms in the VBNC state from the perspective of environmental functions.     

Effects of humic substances and soya lecithin on the aerobic bioremediation of a soil historically contaminated by polycyclic aromatic hydrocarbons (PAHs)

The high hydrophobicity of polycyclic aromatic hydrocarbons (PAHs) strongly reduces their bioavailability in aged contaminated soils, thus limiting their bioremediation. The biodegradation of PAHs in soils can be enhanced by employing surface-active agents. However, chemical surfactants are often recalcitrant and exert toxic effects in the amended soils. The effects of two biogenic materials as pollutant-mobilizing agents on the aerobic bioremediation of an aged-contaminated soil were investigated here. A soil historically contaminated by about 13 g kg(-1) of a large variety of PAHs, was amended with soya lecithin (SL) or humic substances (HS) at 1.5% w/w and incubated in aerobic solid-phase and slurry-phase reactors for 150 days. A slow and only partial biodegradation of low-molecular weight PAHs, along with a moderate depletion of the initial soil ecotoxicity, was observed in the control reactors. The overall removal of PAHs in the presence of SL or HS was faster and more extensive and accompanied by a larger soil detoxification, especially under slurry-phase conditions. The SL and HS could be metabolized by soil aerobic microorganisms and enhanced the occurrence of both soil PAHs and indigenous aerobic PAH-degrading bacteria in the reactor water phase. These results indicate that SL and HS are biodegradable and efficiently enhance PAH bioavailability in soil. These natural surfactants significantly intensified the aerobic bioremediation of a historically PAH-contaminated soil under treatment conditions similar to those commonly employed in large-scale soil bioremediation.     

Bacteria-mediated PAH degradation in soil and sediment

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous in the natural environment and easily accumulate in soil and sediment due to their low solubility and high hydrophobicity, rendering them less available for biological degradation. However, microbial degradation is a promising mechanism which is responsible for the ecological recovery of PAH-contaminated soil and sediment for removing these recalcitrant compounds compared with chemical degradation of PAHs. The goal of this review is to provide an outline of the current knowledge of biodegradation of PAHs in related aspects. Over 102 publications related to PAH biodegradation in soil and sediment are compiled, discussed, and analyzed. This review aims to discuss PAH degradation under various redox potential conditions, the factors affecting the biodegradation rates, degrading bacteria, the relevant genes in molecular monitoring methods, and some recent-year bioremediation field studies. The comprehensive understanding of the bioremediation kinetics and molecular means will be helpful for optimizing and monitoring the process, and overcoming its limitations in practical projects.     

Nutrient-limited biodegradation of PAH in various soil strata at a creosote contaminated site

The effects of nutrient addition on the in situ biodegradation of polycyclic aromatic hydrocarbons in creosote contaminated soil were studied in soil columns taken from various soil strata at a wood preserving plant in Norway. Three samples were used: one from the topsoil (0–0.5 m), one from an organic rich layer (2–2.5 m) and one from the sandy aquifer (4.5–5 m). The addition of inorganic nitrogen and phosphorous stimulated the degradation of polycyclic aromatic hydrocarbons (PAHs) in the top soil and the aquifer sand. These two soils, which differed strongly in contamination levels, responded similarly to nutrient addition with the corresponding degradation of 4-ring PAHs. The ratio between available nitrogen (N) and phosphorous (P) might explain the degree of degradation observed for the 4-ring PAHs. However, the degree of degradation of 3-ring PAHs did not significantly increase after nutrient addition. An increase in the respiration rate, after nutrient addition, could only be observed in the topsoil. In the aquifer sand, 4-ring PAH degradation was not accompanied by an increase in the respiration rate or the number of heterotrophic micro-organisms. PAH degradation in the organic layer did not respond to nutrient addition. This was probably due to the low availability of the contaminants for micro-organisms, as a result of sorption to the soil organic matter. Our data illustrate the need for a better understanding of the role of nutrients in the degradation of high molecular weight hydrocarbons for the successful application of bioremediation at PAH contaminated sites.     

Diversity and PAH growth abilities of bacterial strains isolated from a contaminated soil in Slovakia

Different abandoned industrial areas contaminated by polycyclic aromatic hydrocarbons (PAHs) are present in Slovakia. These environmental burdens are very dangerous to the health of human and environment. The bioremediation, based on the use of hydrocarbons degrading microorganisms, is a promising strategy to sanitize these polluted sites. The aim of this investigation was to assess the bacterial diversity of a PAHs-contaminated soil and to select the potential hydrocarbonoclastic bacteria which can be used for different bioremediation approaches. The bacterial strains were isolated on minimal medium agar supplemented with a mixture of PAHs. Seventy-three isolated strains were grouped by ribosomal interspacer analysis in 15 different clusters and representatives of each cluster were identified by 16S rRNA sequencing. The PAHs degradation abilities of all bacterial isolates were estimated by the 2,6-dichlorophenol indophenol assay and by their growth on minimal broth amended with a mixture of PAHs. Different kinds of strains, members of the genus Pseudomonas, Enterobacter, Bacillus, Arthrobacter, Acinetobacter and Sphingomonas, were isolated from the contaminated soil. Four isolates (Pseudomonas putida, Arthrobacter oxydans, Sphingomonas sp. and S. paucimobilis) showed promising PAHs-degrading abilities and therefore their possible employing in bioremediation strategies.     

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.     

植物法生物修复PAHs和矿物油污染土壤的调控研究

选择苜蓿草为供试植物,以污染物含量水平、专性细菌和真菌及有机肥为调控因子,进行了植物法生物修复多环芳烃(PAHs)和矿物油污染土壤的调控研究。结果表明,PAHs和矿物油的降解率与有机肥含量呈正相关,增加有机肥5%,可提高矿物油降解率17.6%～25.6%,PAHs降解率9%.在植物存在条件下,土壤微生物降解功能增强。多环芳烃总量的平均降解率比无植物对照土壤提高2.0%～4.7%.投加特性降解真菌可不同程度地提高土壤PAHs总量和矿物油的降解率。真菌对萤蒽、芘和苯(a)蒽/(艹屈)的降解有明显促进作用。而细菌能明显提高苊稀/芴、蒽和苯(a)萤蒽/苯(k)萤蒽的降解率。     

Molecular biology approaches for understanding microbial polycyclic aromatic hydrocarbons (PAHs) degradation

The known or suspected hazards of polycyclic aromatic hydrocarbons (PAHs) have provoked enormous concentration and endeavours to relieve or eliminate these precarious compounds from miscellaneous environments including soil, water and air. Among various interventions, biodegradation is an appealing approach for its comparative high efficiency and preferable safety. Microorganisms played crucial role in biodegradation of PAHs. Traditional access mainly including culture-dependent procedures has discovered and isolated PAHs-degrading microorganisms which could be subsequently applied to specific contaminated locus. Although certain progress has been achieved owing to traditional methods, much details in PAHs bioremedation leave pending because of the complexity nature of this process. As the rapid development of biology, molecular techniques such as PCR, fingerprinting technique (mainly DGGE), DNA hybridization technique and gene reporters technique have been intensively applied to gain further insight into the mechanism of PAHs degradation. These techniques not only proved the existence and role of uncultivable microorganisms in the whole population of PAHs degrading related microbials, but also made it possible to revealed the otherwise undetectable complex relationships between multi-microorganism concerned in PAHs biodegradation. Application of such techniques in the field of PAHs biodegradation were reviewed in this article.