Screening for plants and rhizospheral fungi with bioremediation potency of petroleum-polluted soils in a Tehran oil refinery area

The contamination of soils by toxic and/or hazardous organic pollutants, especially with crude oil, is a widespread problem. This study was conducted in a petroleum-contaminated area in a Tehran oil refinery to find petroleum-resistant plants and their rhizospheral fungal strains with bioremediation potency. The plants growing in the oil-polluted area were collected and determined taxonomically. Root samples of the plant species were collected from a polluted area and fungal strains determined by laboratory methods and taxonomical keys. The growth ability of the isolated fungal strains was studied in media containing 1%–15% crude oil. Results showed that seven plant species were of the highest density in the contaminated area: Alhagi persarum, Hordeum marinum, Peganum harmala, Phragmites australis, Prosopis farcta, Salsola kali, and Senecio glaucus. The root-associated fungi were isolated and showed that the fungal variation in the oil-polluted area is higher than that in a non-polluted area. The growth assay of isolated fungal strains showed that all studied fungal strains were able to form colonies at the applied concentrations but Alternaria sp. and Rhizopus sp. were the most resistant ones. Some plants were resistant to oil pollution, which also had positive effects on the fungal strains.     

典型POPs的生物降解修复技术研究与发展

生物吸附与降解是解决持久性有机污染物（POPs）最有潜力的方法之一,有必要介绍利用微生物把目标污染物转化为易降解的物质甚至矿化的POPs修复原理及其技术。对此,概述了近年来国内外基于微生物通过膜融合、胞质融合和核融合形成能够降解POPs的杂种细胞的细胞融合技术;基于降解性质粒的相容性,把能够降解不同污染物的质粒组合到一个菌种中,形成多质粒的新菌种,使微生物由于代谢途径的改变能够矿化POPs的基因工程菌构建技术;基于通过某些载体把酶固定于其中实现活性稳定、可以回收及可重复利用的酶固定化技术,以及基于降解菌活性酶分子亚基置换、降解菌活性酶的定点突变、降解酶的体外定向进化这几方面的酶构建技术;进一步分析基于分子生物学提高POPs生物修复能力的原理,指出经生物技术改造的工程菌和固定化酶未能进入实际应用的障碍所在。以多溴联苯醚（PBDEs）的微生物细胞吸收和降解机理作为典型POPs生物修复的案例,强调生物降解的过程强化需要建立多尺度上功能方面的适合;提出了分子生物学与基因工程学的结合在解决POPs环境污染方面未来的基础科学问题与研究思路。综合上述,典型POPs的生物修复技术的构建需要考虑宏观污染物协同降解的工艺理论,在基因水平、分子水平、反应器水平及工程水平上追求更高功能方面的适合。     

石油污染生物修复研究进展

石油污染多见于油田附近的土壤污染和海上油轮泄漏造成的海域污染,自1970s便出现了利用微生物降解石油污染物的生物修复研究,总结了1970s至今的相关文献发现石油污染生物修复技术受到越来越多的关注,其目前的主要研究方向包括:添加辅助营养物质或辅助乳化剂、石油污染降解过程的生物标记研究、菌株具体降解途径、工程示范研究.而由于石油污染成分复杂,不同微生物可利用的石油底物不同,降解途径也不同,因此传统的石油污染生物修复研究存在效率不高、难以维持等问题,而随着1990s以来分子生物学技术的迅速发展,其在石油污染生物修复中得到越来越多的应用,并有效地提高了修复效率.其应用主要包括以下两方面:(1)在掌握已有石油污染物生物降解途径和降解基因的基础上,研究针对石油污染不同底物的高效降解菌株,构建高效基因工程菌或功能互补的混合菌剂.譬如石油污染物的生物降解过程中,一系列的加氧酶/羟化酶起着最重要的作用,其中包括了单加氧酶和双加氧酶等.它们一般作用于降解的加羟基或后续的开环过程.而不同的脱氢酶、脱羧基酶、辅酶A连接酶等,则对底物加氧后的降解起着重要作用.因此本文重点分析整理了一系列典型石油污染物降解途径中的加氧酶及其参考菌株.(2)由于下游多态性分析方法的进步,越来越多的研究利用PCR对修复过程中群落的重要降解基因进行扩增,譬如对芳烃开环有重要作用的儿茶酚1,2-双加氧酶(C120)、儿茶酚2,3-双加氧酶(C23O)以及对长链烷烃降解起作用的alkB,alkM等基因,并进而应用rDNA扩增及限制性位点分析、梯度凝胶电泳、末端限制性片段长度多态性分析等方法监测研究石油污染的生物降解过程.本文总结了近年来石油污染修复中应用上述方法的研究,为今后的石油污染生物修复工作提供参考.     

Degradation of crude oil by a mixed population of bacteria isolated from sea-surface foams

A mixed bacteria population (EM₄) was isolated from foams formed on the surface of a zone chromically polluted by hydrocarbons (Gulf of Fos, French Mediterranean coast, October 1981). The population was able to degrade crude oil very effectively in the presence of sea water supplemented with nitrogen, phosphorus and iron. The percentage of hydrocarbon degradation was 81% at 30°C, pH 8, and partial oxygen pressure of 100%. After 12 d incubation, 92 and 83% of satured and aromatic compounds (mono-, di- and triaromatics) were degraded, respectively, as well as 63% of polar products and 48.5% of asphaltenes. Maximum degradation was attained at a sodium chloride concentration of between 400 and 800 mM with Population EM₄, which is constituted of 8 strains, four of which are weak halophiles. Bacterial growth on hydrocarbons induces the production in the culture medium of surface-active agents which are able to emulsify the substrate. There is high specificity between the nature of the growth substrate and such emulsifying activity, particularly as far as petroleum is concerned: only the culture medium from Population EM₄ is able to emulsify petroleum. These surface-active agents contain sugars and lipids (fatty acids, mono- and diglycerides). The foams, which always contain a high concentration of both hydrocarbons (100 to 180 mgl^-1) and bacteria that are able to grow on these types of substrates, have a strong emulsifying activity. Our results would seem to demonstrate the importance of biosurfactants in the elimination of hydrocarbons from polluted biotopes.     

烷烃降解菌SY16的筛选、鉴定及降解能力测定

油田生产和运输中经常发生原油落地以及漏油现象,造成大量的石油进入地表土壤,从而产生环境污染。针对原油对土壤产生的环境污染问题,对微生物降解烷烃的能力进行了研究。在以正十六烷为唯一碳源的HDM培养基中,从扶余油田东区采油三厂经常被含油废水浸泡的土壤中,分离、筛选出一株高效降解正烷烃的菌株SY16。经形态学观察和生理生化特征研究,鉴定为施氏假单胞杆菌(Pseudomonas stutzeri)。通过摇瓶试验得出两菌株的最适生长条件为30℃,培养基初始pH 8.0,摇床转速为180 r/min,接种量为1.0%。在最适生长条件下,分别对不同初始质量浓度烷烃进行降解率试验。结果表明,两菌株降解正烷烃的能力显著,当培养基中初始正烷烃含量为50 mg/L时,24 h能全部降解。当混合烷烃中各烷烃的初始质量浓度为50 mg/L时,在24 h对正十烷、正十二烷、正十六烷和正十八烷的降解率分别达到47.0%、42.6%、38.8%、36.2%。     

Biodegradation of crude petroleum and petroleum products by fungi isolated from two oil seeds (melon and soybean)

Crude petroleum oil degrading fungi were isolated from two oil seeds, Cucumeropsis mannii (melon) and Glycine max (soybean) seeds in the presence and absence of petroleum fumes. An assessment of the relative ability of each fungus to degrade crude petroleum, diesel and kerosene on minimum salt solution was done using change in optical density read on spectrophotometer. Twenty-one fungal species (14 genera) were isolated altogether during this experiment. These include eight species of Aspergillus; one species each of Botryodiplodia, Bipolaris, Cladosporium, Cunnighamella, Dreschlera, Fusarium, Helminthosporium, Macrophomina, Mucor, Paeciliomyces, Penicillium, Rhizopus and Talariomyces. It was evident that most of the fungi tested were able to biodegrade the crude petroleum oil, though at different rates. Bipolaris had a low rate of biodegradation of the petroleum oil of all the fungal species isolated Botryodiplodia theobromae had the highest degrading ability on the crude oil, while Aspergillus flavus had the least after 40 days of incubation. Aspergillus flavus had the highest ability to biodegrade diesel while A. niger had the least ability. In kerosene, Macrophomina phaseolina had the highest ability while A. niger had the least ability to biodegrade it. There was fluctuation in the growth pattern of the fungi in the petroleum oil medium. The implication of these are discussed.     

Impacts of crude oil on the germination and growth of cress seeds (Lepidium sp.) after bioremediation of agricultural soil polluted with crude petroleum using "adapted" Pseudomonas putida

The impacts of crude oil on the germination, growth and morphology of cress seeds (Lepidium sp.) after bioremediation of agricultural soil polluted with crude petroleum using "adapted" Pseudomonas putida (PP) were examined for 15 days. At day 15 there was 100% germination in the untreated control samples, the mean height of the seedlings was 75.8 +/- 2.6 mm and all appeared to have grown morphologically normal. In the experimental samples treated with oil and PP inoculation, there was 98% germination and the seedlings reached a height of 63.8 +/- 6.9 mm; again, morphologically the seedlings appeared normal. However, in the control samples treated with oil but without PP inoculation, there was 31-38% germination and seedling heights of 34.2 +/- 11.4-42.3 +/- 8.5 mm with abnormal morphology. Treatment of oil-impacted agricultural soil with PP as a bioremediation agent does produce soil which is capable of growing larger and healthier plants than where bioremediation has not taken place.     

Combined bioremediation for lead in mine tailings by Solanum nigrum L. and indigenous fungi

Lead-contaminated mine tailings were bioremediated using microbial/phyto remediation. The optimum lead accumulation and tolerance capacity of the plant–microbe partnership were investigated, and their mechanisms were evaluated further under varied levels of lead contamination through a flowerpot experiment in a greenhouse. Enzymes activities revealed that bioremediation has improved fertility and metabolism of tailing soil. The removal efficiency of lead was in the order of microbial/phytoremediation?>?phytoremediation. Solanum nigrum L. was not shown to be a hyperaccumulator for lead. Mucor circinelloides significantly enhanced the growth response and lead accumulation in plants more than Mortierella and Trichoderma asperellum. Moreover, Mortierella was discovered to have good metal tolerance capacity under high Pb concentrations (1200 and 1600?mg?kg^?1). The results for lead bioavailability showed that phytostabilisation serves as a major repair pathway for S. nigrum L. Effective fractions were immobilised for decreased bioavailability by T. asperellum and M. circinelloides. On the contrary, an increased amount of lead was mobilised for increased bioavailability by Mortierella. This study provides new insights into the feasibility of using S. nigrum L. and the aforementioned indigenous fungus strains for large-scale bioremediation of mine tailings.     

Use of metal-reducing bacteria for bioremediation of soil contaminated with mixed organic and inorganic pollutants

Mixed contamination by organic and inorganic compounds in soil is a serious problem for remediation. Most laboratory studies and field-scale trials focused on individual contaminant in the past. For concurrent bioremediation by biodegradation and bioleaching processes, we tested metal-reducing microorganism, Geobacter metallireducens. In order to prove the feasibility of the coupled process, multiple-contaminated soil was prepared. Mineralogical analyses have shown the existence of labile forms of As(V) as amorphous and/or weakly sorbed phases in the secondary Fe oxides. In the biotic experiment using G. metallireducens, biodegradation of toluene and bioleaching of As by bacteria were observed simultaneously. Bacteria accelerated the degradation rate of toluene with reductive dissolution of Fe and co-dissolution of As. Although there have been many studies showing each individual process, we have shown here that the idea of concurrent microbial reaction is feasible. However, for the practical use as a remediation technology, more details and multilateral evaluations are required in future studies.     

Use of metal-reducing bacteria for bioremediation of soil contaminated with mixed organic and inorganic pollutants

Mixed contamination by organic and inorganic compounds in soil is a serious problem for remediation. Most laboratory studies and field-scale trials focused on individual contaminant in the past. For concurrent bioremediation by biodegradation and bioleaching processes, we tested metal-reducing microorganism, Geobacter metallireducens. In order to prove the feasibility of the coupled process, multiple-contaminated soil was prepared. Mineralogical analyses have shown the existence of labile forms of As(V) as amorphous and/or weakly sorbed phases in the secondary Fe oxides. In the biotic experiment using G. metallireducens, biodegradation of toluene and bioleaching of As by bacteria were observed simultaneously. Bacteria accelerated the degradation rate of toluene with reductive dissolution of Fe and co-dissolution of As. Although there have been many studies showing each individual process, we have shown here that the idea of concurrent microbial reaction is feasible. However, for the practical use as a remediation technology, more details and multilateral evaluations are required in future studies.     

Use of metal-reducing bacteria for bioremediation of soil contaminated with mixed organic and inorganic pollutants

Mixed contamination by organic and inorganic compounds in soil is a serious problem for remediation. Most laboratory studies and field-scale trials focused on individual contaminant in the past. For concurrent bioremediation by biodegradation and bioleaching processes, we tested metal-reducing microorganism, Geobacter metallireducens. In order to prove the feasibility of the coupled process, multiple-contaminated soil was prepared. Mineralogical analyses have shown the existence of labile forms of As(V) as amorphous and/or weakly sorbed phases in the secondary Fe oxides. In the biotic experiment using G. metallireducens, biodegradation of toluene and bioleaching of As by bacteria were observed simultaneously. Bacteria accelerated the degradation rate of toluene with reductive dissolution of Fe and co-dissolution of As. Although there have been many studies showing each individual process, we have shown here that the idea of concurrent microbial reaction is feasible. However, for the practical use as a remediation technology, more details and multilateral evaluations are required in future studies.

     

柴油污染土壤生物修复对土壤酶活性的影响

在柴油污染土壤的生物修复过程中,分析了土壤中柴油降解菌数量和3种土壤酶活性(过氧化氢酶、脱氢酶和脂酶)等生物活性指标与土壤中柴油去除率的相关性.结果表明,土壤受到柴油污染后的一段时间后过氧化氢酶、脱氢酶和脂酶的活性上升,而后随着土壤中石油烃的降解,脂酶又不断降低.进一步分析表明脂酶活性与柴油降解率及柴油降解菌数量都具有很好的正相关性,可以采用土壤脂酶活性来指示柴油生物降解成效.     

Cellulose degradation by Lulworthia floridana and other lignicolous marine fungi

Gravimetric analyses of cellulose (Solka Floc) utilization by representative marine Ascomycetes, including Lulworthia floridana, Lindra sp., Torpedospora sp. and Halosphaeria mediosetigera, have shown noteworthy activity based on loss of weight of cellulose by the various fungi. Particularly striking activity is evidenced by L. floridana and Torpedospora sp., with >50% cellulose degradation after 3 weeks of fungal growth. Comparable studies with the deuteromycete, Dendryphiella salina, showed >50% loss within 6 days. Dissimilar responses by various L. floridana isolates are noted. Intensive degradative activity at pH's of 6 to 8 is common along with negligible amounts of cellulase (Cx units). Adsorption of the enzyme to the mycelia or to the cellulose particles in the medium is suggested. Earlier laboratory analyses of fungal degradation of Manila cordage compare favorably with present gravimetric studies and support field observations on the significance of fungal infestation of wood, particularly that incited by the Lulworthia floridana group.This work was supported by Grant GM 12482 from the National Institute of Health and Office of Naval Research Contract No. 137-792 to the Institute of Marine Sciences, University of Miami. Contribution No. 950 from the Institute of Marine Sciences, University of Miami.     

Degradation of methyl-phenanthrene isomers during bioremediation of soil contaminated by residual fuel oil

Phenanthrene and methyl-phenanthrenes are major aromatic pollutants originating in particular from fuel oil. Phenanthrene is usually degraded faster than methyl-phenanthrenes under geological and environmental conditions. Here, we report a preferential and accelerated biodegradation of methyl-phenanthrenes versus phenanthrene in soil contaminated by fuel oil. The polluted soil was mixed with sawdust and sand to form a homogenized biopile. The biopile was continuously sprayed with microbial consortia isolated from crude oil?Ccontaminated soil and treated by biosurfactants and nutritive substances for biostimulation. During a 6-month bioremediation experiment, a steady increase in the relative abundance of phenanthrene compared to methyl-phenathrenes was observed by gas chromatography?Cmass spectrometry. The increase was the highest for trimethyl-phenanthrenes, with a phenanthrene/trimethyl-phenanthrenes ratio increasing from 0.42 to 2.45. By contrast, the control, non-stimulated samples showed a ratio decrease from 0.85 to 0.11. Moreover, the results showed that the level of degradability depends on the number of methyl groups.     

三氯乙烯降解菌的分离鉴定及其降解特性

三氯乙烯是一种具有"三致"效应的有机氯代烃化合物,作为一种重要的化工原料在工业上广泛应用,同时也造成了大量的三氯乙烯进入自然环境,引起了严重的环境污染.为获得更为丰富的三氯乙烯降解微生物资源,利用水-硅油双相系统从实验室高浓度三氯乙烯胁迫底泥中,分离筛选得到两株三氯乙烯降解菌WF1、FT10.在三氯乙烯初始质量浓度为5 mg·L-1的条件下,培养72 h,菌、WF1、FT10对三氯乙烯的降解率分别为53.36%、48.06%;在500 mg·L-1乙酸钠作为共代谢基质的情况下,降解率分别为55.95%、55.62%,降解速率明显提高.根据形态学观察、16项生理生化实验和16S rRNA序列分析结果,将菌株WT1归为Achromobacter xylosoxidans,将FT10归为Sporosarcina aquimarina.对菌株培养条件进行优化,经Slide Write统计软件拟合,菌株WT1和FT10在牛肉膏蛋白胨液体培养基上的最适生长温度分别为33.7℃和35.4℃,最适生长pH分别为7.6和7.9.     

黑臭河道生物修复中3种不同增氧方式比较研究

利用叶轮式曝气机、水下式曝气机、射流式曝气机等3种不同曝气方式的曝气设备进行了黑臭河涌曝气试验。研究表明，不同增氧方式对黑臭河道水体增氧效率不同，水下式曝气机、叶轮式曝气机均可在黑臭河道下游形成一段绿色水而，水车式曝气机下游变绿河段长度为15．7m，叶轮式曝气机下游变绿河段长度为6．3m，射流式曝气机不能形成明显的绿色水而。无论足河道水体增氧效果、CODcr、NH3-N去除效果，还足河道菌-藻生态系统的建口、自净能力的肩动，水下式增氧机均优于其它两种增氧机，而且存在投资少、安装维护方便、运行费用低等优点。适应于河道窄、水流缓、截污难度大的城郊中小型黑臭河道的治理。     

The economic implications of recycling exhaustible natural resources: The case for crude oil

Regardless of whether the bulk of decision-making in an economy is done by a central unit or by decentralized smaller units, the government can act to propose guidelines to individual agents. This is of particular importance when the activities of the latter cause aggregative or social problems which are not directly acted upon by the smaller agents. The purpose of this paper is to set up a model by which a central authority can make choices in the presence of two pressing social problems, namely, a diminishing domestic supply of an exhaustible resource and the contamination of the environment through discharged waste materials.The model itself takes the form of an integer-linear programming problem which runs through discrete time to a finite horizon. Besides the traditional modes of “virgin” exploration and production and/or importation from abroad, society is also given the choice of recycling. Society will choose combinations of the above three to minimize the costs of satisfying fixed (projected) oil product demands in the future. The costs include those for increasing exploration for virgin refineries; for collection, refining and transportation for refineries and for the cost to society of discharges of waste-oil into the environment. The constraints include process flow restrictions, import quotas, capacity limits and discharge restrictions as well as fixed demands.An effort was made to keep the model as general as possible. Although no numerical solution is obtained in this paper, we feel that the policy implications of some presumed solution (possible through the use of a well-known algorithm for mixed variable problems) are worth examining. They revolve around the model itself, citing the potential attractiveness of recycling as the other two alternatives become increasingly expensive, and as development of alternatives to oil progresses at an alarmingly slow rate. Also mentioned are problems relating to the potential demands for recycled versus virgin oil products, balance-of-trade problems, and the mutability of social and economic institutions in the crisis of economic adjustment that much of the world is now facing.     

Some observations on the interactions of marine protozoa and crude oil residues

Marine protozoa were observed to take up Kuwait crude-oil residues in the laboratory and the field. The results suggest that the ingestion occurs only whilst the organisms are feeding on normal food sources.     

Effects of Arbuscular mycorrhizal fungi isolated from white clovers (Trifolium repens L) on soil bacteria and fungi

White clover potted experiments were performed to investigate the effects of seven indigenous arbuscular mycorrhizal fungi (AMF) communities isolated from different test plots subjected to long-term fertilisation on soil enzyme activities, number of soil bacteria and fungi. The results showed that the inoculation of arbuscular mycorrhizal fungi communities increased the mycorrhizal infection rate of the plants and promoted the growth of plants. The Mnp treatment was most effective. The shoot biomass, root biomass, potassium and nitrogen uptake of the white clover in Mnp treatment group were increased by 61.54%, 84.00%, 62.50% and 46.71% respectively, compared with those in non-inoculation treatment. The inoculation of AMF communities had little effect on the number of bacteria in the soil, but significantly increased the number of soil fungi. Mnk treatment group had the highest number of fungi in the soil, which was 9.91 times that of the non-inoculation treatment group. The catalase and dehydrogenase activities were both significantly improved in Mnp treatment by 28.12% and 205.38% respectively, compared with those of the control treatment (-M). The urease, invertase and cellulase activities reached the highest levels in the Mck treatment; they were increased by 142.79%, 41.17% and 77.62% respectively, compared with those of the control treatment. Pearson correlation analysis showed that the soil enzyme activity was not correlated with the mycorrhizal infection rate, but correlated with the spore number of the AMF community. The impact of AMF community on soil quality is important for us to understand the function of the ecosystems. Relevant study provides important guidance for maintaining the balance of the soil-plant system and the development of sustainable agriculture.