固废拆解场污染土壤中多环芳烃降解菌的筛选鉴定与降解特性

以腐植酸(HA)溶液为吸附剂、从受多环芳烃污染的土壤中分离出来的降解菌制成为生物修复剂,以多环芳烃(PAHs)萘、菲、芘、荧蒽、苯并蒽、苯并芘为土壤污染物,对PAHs污染土壤进行修复实验。目的是筛选与分离吸附于HA的PAHs降解菌,研究HA与降解菌的协同效应对PAHs的降解效率的影响。用经过HA吸附的PAHs富集分离培养出1株高效降解菌株,命名为Tzyx3,鉴定其为解脂耶氏酵母菌(Yarrowia lipolytica)。15 d后,土壤中萘、菲、芘、荧蒽、苯并蒽、苯并芘的降解率分别为90.7%、91.0%、74.7%、86.9%、84.7%和74.7%,表明Tzyx3和HA在PAHs污染土壤中存在协作关系,Tzyx3能够直接利用HA对土壤中的多环芳烃进行降解。     

三株优势菌对多环芳烃的降解性能研究

多环芳烃具有毒性、生物蓄积性和半挥发性,并能在环境中持久存在。生物修复处理具有费用低、效果好、污染物残留量低、不产生二次污染、能够保持或改善植物生长的土壤结构等优点。实验分别在对单一菌株、两两混合菌株及三株菌混合等三种情形下,对蒽、菲、芘的降解作用进行了研究。研究结果表明：单一菌株对蒽、菲、芘有一定的降解能力,菌株混合时,对蒽、菲的降解率有所提高;三株菌种混合时,黄杆菌对放线菌、红球菌的生长过程有抑制作用;蒽、菲、芘的降解过程会不断交替进行着产酸和脱羧过程,使降解液pH值出现波动;同时在降解过程中,菌体能产生表面活性物质,这有利于蒽、菲、芘的生物降解转化。     

菌源对多环芳烃降解菌的筛选及降解性能的影响

高效降解菌的筛选对利用生物修复技术有效去除环境中的多环芳烃具有重要意义。分别以石油污染土壤和焦化废水活性污泥为菌源,分离出芘降解菌和混合PAHs(菲、荧蒽和芘)降解菌共14株并对其降解性能进行对比研究。结果表明,筛选得到的菌株分别属于9个菌属,其中2种菌源共有的菌属为Mycobacterium sp.、Ralstonia sp.和Shinella sp.。芘和PAHs的高效降解菌(CP16和CM32)均属于分支杆菌属(Mycobacterium),来源于焦化废水活性污泥;菌株CP16对芘(50mg/L)的7 d降解率为74.99%,CM32对PAHs(菲50 mg/L、荧蒽和芘各10 mg/L)的7 d降解率为100%。因此,以焦化废水活性污泥为菌源更有利于获得高效的多环芳烃降解菌。     

降解菌对堆肥中多环芳烃降解作用的研究

通过在堆肥中加入经过驯化的降解菌这种土壤有机污染生物修复技术 ,对堆肥中多环芳烃的浓度变化进行监测 ,从而了解降解菌对堆肥中多环芳烃的降解作用。实验结果表明 ,降解菌的加入能明显地提高多环芳烃的降解率 ,本次实验中 ,菲、芴的去除率提高了 2 5 %左右 ,芘的去除率提高了约 4 5 %。     

降解菌对堆肥中多环芳烃降解作用的研究

通过在堆肥中加人经过驯化的降解菌这种土壤有机污染生物修复技术，对堆肥中多环芳烃的浓度变化进行监测，从而了解降解菌对堆肥中多环芳烃的降解作用。实验结果表明，降解菌的加人能明显地提高多环芳烃的降解率，本次实验中，菲、芴的去除率提高了25％左右，芘的去除率提高了约45％。     

盐环境下降解菌群对芘的降解特性研究

以芘为多环芳烃(PAHs)的代表物,利用1.0%盐度的无机盐培养基从石油污染土壤中富集出高效嗜盐PAHs降解菌群。通过DNA测序鉴定,菌群中对芘起重要降解作用的是Rhodanobacter、Pseudomonas、Mycobacterium,3者碱基比例达到31.82%。14d内,萘、菲、荧蒽、芘、苯并[a]芘5种PAHs的挥发损耗均可忽略不计。筛选得到的菌群降解芘的最佳条件为:酵母粉质量浓度为120mg/L,盐度不超过1.0%,无需额外添加甲基-β-环糊精。筛选出的降解菌群对芘的最佳降解条件可用于降解萘、菲、荧蒽和苯并[a]芘等其他PAHs,但随着PAHs环数增加,分子量增大,降解率降低。在最佳条件下降解14d时,萘、菲、荧蒽、芘、苯并[a]芘5种PAHs的降解率可分别达100.00%、85.48%、51.92%、56.28%、50.45%。     

一株多环芳烃降解菌的筛选及其降解特性

微生物修复是治理土壤多环芳烃(polycyclic aromatic hydrocarbons, PAHs)污染的主要方法,而高效降解菌筛选是微生物修复技术的重要基础。从北京焦化厂土壤中筛选分离得到一株PAHs降解菌Q3,通过生理生化和16S rDNA等分析手段鉴定其为Rhodococcus rhodochrous。结果表明:该菌株对芘的耐受能力较强,可降解初始浓度为200 mg·L~(-1)的芘;该菌株具有降解广谱性,可利用苯并[a]芘、苯并[b]荧蒽、二苯并[a,h]蒽、苯并[g,h,i]苝等9种PAHs为唯一碳源进行代谢,特别是对苯并[a]芘等高环PAHs具有较好的降解效果;此外,该菌株可有效降解模拟液中的混合PAHs,并且对野外被PAHs长期污染的土壤具有较好的强化修复效果。投加菌株处理后的处理组与对照组相比,土壤PAHs总去除率提高了24%。以上结果表明该菌株对环境中被PAHs污染的土壤具有较好的强化修复潜力,可为PAHs污染土壤的微生物修复技术提供技术参考。     

固定化微生物菌种的筛选与鉴定

以菲、芘作为降解对象 ,对多种菌株进行筛选 ,从中挑选出降解率最高的两株菌 ,细菌和真菌各一株 ,并对其生长曲线进行测定 ,为菌种的固定化提供了一定的依据。同时对菌种进一步鉴定 ,细菌为动胶杆菌 (Zoogloeasp .) ,在 72h内对菲、芘的降解率为 87 82 %和 4 9 2 2 % ;真菌为镰刀菌 (Fuariumsp .) ,在 2 16h内对菲、芘的降解率为 93 32 %和 96 2 9%。     

产漆酶食用菌的粗酶液对多环芳烃降解研究

漆酶是一种含铜的多酚氧化酶,可以降解多种有机污染物,其中包括多环芳烃。但是由于纯漆酶的价格昂贵,限制了在环境修复中的应用。采用液态和固态2种方式培养了食用菌Pleurotus ostreatus和Coprinus comatus,并考察了固态培养的粗酶液对多环芳烃的降解和去毒能力,结果发现2种真菌均可产漆酶,但不产木质素过氧化物酶和锰过氧化物酶,其中固态培养的漆酶产量高于液态培养,且C.comatus的漆酶产量大于P.ostreatus。2种真菌固态培养的粗酶液对多环芳烃均有一定的降解和去毒作用,且P.ostreatus粗酶液的漆酶活性虽然较低,但是对多环芳烃降解率和去毒效果却优于C.comatus,这可能是P.ostreatus的粗酶液中含有较多的调节物质造成的。P.ostreatus的固态发酵粗酶液对蒽、苯并[a]芘、苯并[a]蒽、苊等均有较高的降解率(50%以上),但是对生物有效性高的萘的降解率却较低,这种降解特征可能与底物的电离势大小有关。     

不同浓度鼠李糖脂对土壤多环芳烃去除率及微生物群落结构的影响

研究了鼠李糖脂浓度对3种多环芳烃(PAHs)菲、荧蒽和芘去除率的影响,以及对土壤微生物群落结构的影响。结果表明,培养35d后,鼠李糖脂质量浓度为100～200mg/kg时,菲、荧蒽和芘的去除率相对最高,土壤中细菌16SrRNA基因和phnAc基因的丰度也达到最大。土壤中天然的PAHs降解菌群主要是假单胞菌属(Pseudomonas)、芽孢杆菌属(Bacillus)、鞘氨醇单胞菌属(Sphingomonas)、溶杆菌属(Lysobacter)和环脂酸芽孢杆菌属(Tumebacillus)等;加入鼠李糖脂后,赭黄嗜盐囊菌属(Haliangium)和土壤红杆菌属(Solirubrobacter)的丰度增加,促进了PAHs更高效的降解。     

Removal of polycyclic aromatic hydrocarbons from soil: a comparison between bioremoval and supercritical fluids extraction

Polycyclic aromatic hydrocarbons (PAHs) are carcinogenic substances which are resistant to environmental degradation due to their highly hydrophobic nature. Soils contaminated with PAHs pose potential risks to human and ecological health, therefore concern over their adverse effects have resulted in extensive studies on their removal from contaminated soils. The main purpose of this study was to compare experimental results of PAHs removal, from a natural certified soil polluted with PAHs, by biological methods (using bioaugmentation and biostimulation in a solid-state culture) with those from supercritical fluid extraction (SFE), using supercritical ethane as solvent. The comparison of results between the two methods showed that maximal removal of naphthalene, acenaphthene, fluorene, and chrysene was performed using bioremediation; however, for the rest of the PAHs considered (fluoranthene, pyrene, and benz(a)anthracene) SFE resulted more efficient. Although bioremediation achieved higher removal ratios for certain hydrocarbons and takes advantage of the increased rate of natural biological processes, it takes longer time (i.e. 36 d vs. half an hour) than SFE and it is best for 2-3 PAHs rings.     

Efficacy of in-situ for the remediation of PAH contaminated soils

Polycyclic aromatic hydrocarbons (PAHs) are of environmental concern because many PAHs are either carcinogens or potential carcinogens. Petroleum products are a major source of PAHs. The occurrence of PAH contamination is widespread and novel treatment technologies for the remediation of contaminated soils are necessary.Ozone has been found to be extremely useful for the degradation of PAHs in soils. For these compounds, the reaction with molecular ozone appears to be the more important degradation pathway. Greater than 95% removal of phenanthrene was achieved with an ozonation time of 2.3 h at an ozone flux of 250 mg h⁻¹. After 4.0 h of treatment at an ozone flux of 600 mg h⁻¹, 91 % of the pyrene was removed. We have also found that the more hydrophobic PAHs (e.g. chrysene) react more slowly than would be expected on the basis of their reactivity with ozone, suggesting that partitioning of the contaminant into soil organic matter may reduce the reactivity of the compound. Even so, after 4 h of exposure to ozone, the chrysene concentration in a contaminated Metea soil was reduced from 100 to 50 mg kg⁻¹ .Ozone has been found to be readily transported through columns packed with a number of geological materials, including Ottawa sand, Metea soil, Borden aquifer material and Wurtsmith aquifer material. All of these geological materials exerted a limited (finite) ozone demand, i.e. the rate of ozone degradation in soil columns is very slow after the ozone demand is met. Moisture content was found to increase the ozone demand, most likely owing to the dissolution of gaseous ozone into the pore water. As once the initial ozone demand is met, little degradation of ozone is observed, it should be possible to achieve ozone penetration to a considerable distance away from the injection well, suggesting that in-situ ozonation is a feasible means of treating uncontaminated unsaturated soils. This is substantiated by two field studies where in-situ ozonation was apparently successful at remediating the sites.     

COMPARISON OF IN VITRO ACTIVITIES OF AMPHOTERICIN,CLOTRIMAZOLE, ECONAZOLE,MICONAZOLE, AND NYSTATIN AGAINST FUSARIUM OXYSPORUM

The inhibitory activity of amphotericin B, clotrimazole, econazole, miconazole and nystatin was compared against Fusarium oxysporum f.sp. radiciscucumerinum. The most efficient antifungal agent against the growth of Fusarium oxysporum was econazole, followed by clotrimazole, miconazole, amphotericin and nystatin. The ED_{5 0} and ED_{9 0} values were 0.053 and 1.002 ppm for econazole, 0.088 and 1.100 ppm for clotrimazole, 0.173 and 3.210 ppm for miconazole, 0.713 and greater than 48 ppm for amphotericin and 3.860 and 16.702 ppm for nystatin. The ED_{5 0} values of nystatin and amphotericin against spore germination of Fusarium oxysporum were determined at 3.1427 ppm and 8.3990 ppm respectively, nystatin was 2.76 times more effective than amphotericin, while no effect was observed after the addition of econazole, clotrimazole and miconazole. The tested azoles were more effective than amphotericin and nystatin on growth inhibition of Fusarium oxysporum but amphotericin and nystatin acted significantly better on spore germination of Fusarium.     

Responses of different fungal and plant species to acetolactate synthase inhibitors and their derivatives

Abstract

The effect of sulfonylurea (SU) acetolactate synthases (ALS) inhibitors (chlorsulfuron and triasulfuron) and their 13 guanidine and 7 azole derivatives was studied on 17 fungal and 21 plant species. The efficacy of chlorsulfuron and triasulfuron against Fusarium oxysporum and Thielaviopsis basicola was higher than carbendazim. Two azole derivatives were highly selective for maize. The antifungal activity spectrum of both guanidine and azole derivatives differed from that of chlorsulfuron and triasulfuron, and did not exert notable antifungal activity in vitro. However, they had significant anti‐Fusarium efficacy on rye that surpassed that of carbendazim.     

A comparative study on the uptake of polycyclic aromatic hydrocarbons by Anodonta californiensis

Uptake of polycyclic aromatic hydrocarbons (PAHs) by the freshwater bivalve mollusc Anodonta californiensis was examined in the presence and absence of surfactant in order to gain further insight into mixture toxicity and to predict whether certain mixtures have negative and/or positive effects on aquatic organisms. In the presence of surfactant, the uptake of anthracene or chrysene was higher than that of naphthalene, given the same concentration in the solution. In the absence of surfactant, the trend was similar, but the uptakes were increased by approximately 100% compared to those in the presence of surfactant. On the uptake of naphthalene, the presence of anthracene showed only minor influence. The uptake of anthracene was affected by both naphthalene and chrysene. The uptake of chrysene was influenced by neither naphthalene nor anthracene. There was no observable displacement of divalent cations from the surface of the gill membrane by any of the PAHs studied.     

Treatment of hydrophobic VOCs in trickling bed air biofilter: Emphasis on long-term effect of initial alternate use of hydrophilic VOCs and microbial species evolution

The main research objective of this study is to enhance the removal of recalcitrant compounds that are not readily bioavailable due to limiting mass transfer rate between the liquid and gas phases. Four trickle-bed air biofilters (TBABs), loaded with pelletized diatomaceous earth support media, were run at an empty bed residence time (EBRT) of 120 sec. After an acclimation period at constant loading rate (LR) of n-hexane (13.2 g m^?3 hr^?1) and intermittent feeding of methanol, n-hexane influent LR was then increased in step-wise fashion to 47.7 g m^?3 hr^?1 for biofilters receiving acidic nutrients (pH 4), and to 36.3 g m^?3 hr^?1 for biofilters receiving nutrient at pH 7. The results have shown that for TBABs receiving nutrient at pH 4, greater elimination capacities were obtained as compared to TBABs working at pH 7. n-Hexane removal efficiency of more than 84% at LR up to 47.7 g m^?3 hr^?1 was obtained for pH 4 nutrient-fed biofilters, while for biofilters with nutrients fed at pH 7, the removal efficiency did not exceed 64% for n-hexane LR of 36.3 g m^?3 hr^?1. The microbial analysis revealed that no fungal community was detected in TBABs run at neutral pH. The fungi communities that were initially acclimating TBABs run at pH 4, namely, Aspergillus niger and Fusarium solani, were not detected at the end of the experiment, while Gibberella moniliformis (Fusarium verticillioides) genus became the dominant species. Gibberella moniliformis (Fusarium verticillioides) was present along all the biofilter media and sustained very high n-hexane elimination at steady-state condition.

Implications:With growing apprehension about sustainability and environmental protection, with limited resources available, and with the passage of the 1990 Amendments to the Clean Air Act, there is more need for using air pollution control techniques that are sound economically and proven environmentally friendly. Biofiltration systems, namely, trickle-bed air biofilters, were for decades recognized as efficient in treating air pollutants. Thus, the application of this technique over a wide industrial spectrum would certainly contribute to reduction of hazardous gas emissions.     

Concentrations and microbial mineralization of four to six ring polycyclic aromatic hydrocarbons in composted municipal waste

Contents of four to six ring polycyclic aromatic hydrocarbons (PAHs) were estimated in twelve composted municipal wastes of different origin and age. By means of clean-up procedures and subsequent gaschromatography nine different PAHs or isomeric mixtures of PAHs could be separated in extracts. Concentrations of PAHs ranged from 0.17 μg perylene to 56.75 μg benz(a)anthracene/chrysene g^?1 compost (dwt). In each compost the same distinct relation between the amounts of individual PAHs was found. In spite of total weight reduction during compost processing (40–60% loss) no accumulation of PAH concentrations in ripe composts was detected. This points to a decay of PAHs by microbial activities during composting. Degradation studies carried out with four ¹⁴C-labelled PAHs indicated that in fresh composts only minor amounts of PAHs can be degraded. However, microbial populations of ripe composts possess considerable capabilities to mineralize these recalcitrant molecules.     

高效联苯降解菌的筛选及其特性

焦化废水属高浓度难降解工业有机废水,其中所含的多环芳烃属难降解有机物,且对环境产生毒害作用。为探索生物强化技术去除焦化废水中多环芳烃类化合物,采用选择性培养和多级富集的方法,以联苯为模型化合物,并作为惟一碳源,从焦化厂废水和污泥中分离和筛选得到6株联苯降解菌。通过逐渐提高底物浓度的方法驯化菌株后,从中筛选出降解效率最高的联苯降解菌株WIS-01,在此基础上进行菌属鉴定、细菌生长情况及联苯降解性能的研究。实验结果表明,3 d内菌株WIS-01对联苯的降解率可达99%以上,可耐受联苯的最高质量浓度为2 g/L。通过形态学、生理生化鉴定和16S rDNA序列比对分析,确定菌株WIS-01属于假单胞菌属,同源性达95%,命名为Pseudomonas sp.WIS-01。     

修复 PAHs 复合污染体系的高效菌群构建及降解特性简

从污染环境分离和筛选得到了9株PAHs降解菌,以其为基本菌种,构建高效修复PAHs复合污染体系的菌群（D）。采用平板稀释涂布计数法对降解体系中菌群（D）的动态结构进行了解析,数据显示菌群内的微生物在降解过程中能相互协作,发挥稳定且高效的降解作用。实验进一步研究了菌群D对单一PAH和混合PAHs的降解特性,结果表明,无论对单一PAH还是混合PAHs,菌群D均具有较强的降解能力。当降解历时6 d,菌群D能使40 mg/L的单一PAH平均降解85.8%,使60 mg/L的混合PAHs平均去除89.4%。菌群D在多环芳烃复合污染体系的生物修复方面具有潜在的应用价值。