富含腐殖酸还原混合菌的污泥厌氧降解对乙酰氨基酚的机制

以杭州市四堡污水处理厂的厌氧污泥为接种污泥,驯化富集了厌氧腐殖酸还原混合菌,加入不同的腐殖酸和碳源以优化驯化条件.结果表明,利用驯化厌氧污泥降解对乙酰氨基酚,1周降解时间内,驯化1个月的含腐殖酸还原混合菌群污泥比普通厌氧污泥降解率高34%,驯化半年的成熟厌氧污泥降解效果更好,降解率达90%以上.驯化厌氧污泥的最佳pH为7.0,Fe3 与腐殖酸同时存在时能进一步提高对乙酰氨基酚的厌氧生物降解效果.     

石油污染土壤中芘高效降解菌群的筛选及降解特性研究

从长期受石油污染土壤中驯化筛选到能以芘为惟一碳源生长的混合菌群GP3,其主要由假单胞菌株GP3A(Pseudomonas sp.)和菌株GP3B(Pandoraea pnomenusa)组成.采用摇瓶振荡培养方法,研究了不同环境条件对混合菌GP3降解芘效能的影响.结果表明,在30℃,150 r/min振荡培养下,混合菌GP3对15 mg/L芘的7 d降解率为90.6%.混合菌GP3降解芘的最适宜温度为35℃,最佳pH值为6.2.加入低浓度葡萄糖(100 mg/L)或菲(10 mg/L)作为共代谢底物,均可提高GP3对芘的降解率.混合菌对芘的降解速率(PDR)与芘的初始浓度呈正相关.研究重金属离子胁迫下GP3对芘的降解时发现,10 ms/L Zn2 的存在对芘降解效能影响较小,Cu2 对芘的降解有抑制作用,Cd2 对混合菌GP3有很强的毒性.     

一株产表面活性剂石油降解菌筛选及其特性

为了从含有原油的样品中筛选出降解性能良好的产生表面活性剂菌株。利用富集、驯化培养、不同配方培养基筛选和排油活性测定,筛选出产高效生物表面活性剂的菌株。在形态特征和生理生化鉴定的基础上,对其16S rDNA序列进行了分析,并分别采用称重法和薄层层析法(TLC)测定其原油降解率和鉴别其表面活性剂的类型。进一步考察了不同种类的碳源和氮源、不同梯度的温度、盐度、酸碱度对其生长和排油活性的影响。筛选出一株高效脂肽类生物表面活性剂的菌株A-08,对其进行形态学、生理生化特性及16S rDNA序列同源分析,此菌株为荧光假单胞菌(Pseudomonas fluorescens)。A-08最适条件为碳源是食用油和液体石蜡,氮源为(NH_4)_2SO_4,温度40℃,盐度20%,pH 7.0,培养7 d后原油降解率为40.37%。实验筛选的菌株能适应较广泛的环境条件,可以对石油污染进行有效生物修复,具有较好的意义和应用价值。     

报废发射药降解菌种选育及降解特性

通过驯化富集培养,从长期受发射药污染的土壤中分离筛选出能以发射药为唯一碳源并具有较高降解能力的微生物混合菌群,混合菌群对发射药样品COD去除率最高可达75.6%。经进一步分离纯化,获得了5株优势菌。实验表明混合菌群的降解能力优于各单一菌种,应以混合菌群为目标菌种。混合菌群最佳降解温度为30～35℃,最佳pH值为7.0。...     

苯胺降解菌的分离和降解特性研究

通过驯化富集培养,从白洋淀底泥中分离筛选出数株能够有效降解苯胺的菌株,经过反复筛选,得到一株能够以苯胺为唯一碳源、高效降解苯胺的菌株BA-1-3.其利用苯胺的最适pH值为7.0,最适温度为30℃,在苯胺浓度为1000 mg/L,180 r/min条件下振荡培养60 h,降解率达到80%以上.经鉴定,菌株BA-1-3属苍白杆菌属(Ochrobactrumsp.).     

耐盐性毒死蜱降解混合菌的构建及其降解特性

为明确蜡状芽孢杆菌(Bacillus cereus)混合菌株对毒死蜱的降解效果,采用正交实验的方法构建混合菌。以混合菌对毒死蜱的降解率和菌株的生长量为依据,利用单一因素实验考察了不同因素对混合菌降解毒死蜱的影响。结果表明:构建的混合菌中三菌株的体积比为1∶1∶3。在含80 mg/L毒死蜱的反应体系中,最适接菌量为8%(V/V),最适pH为7。在实验浓度下,混合菌对毒死蜱的降解符合一级动力学方程。混合菌对盐分有较高的耐受度,当反应液中氯化钠浓度在20～100 g/L之间时,混合菌对80 mg/L毒死蜱的降解率最高达61%。     

生物接触氧化法处理稠油污水实验研究

将从稠油污水中筛选出的3株高效烃类降解菌株HD-1、HD-2和HD-3用于稠油污水处理,研究了单一菌株和混合菌株对原油和COD的去除率。实验结果表明,单一菌株对原油和COD具有很好的去除效果,混合菌株对原油和COD去除效果更加显著。室内模拟实验结果表明,在停留时间为6 h时,含油量和COD分别为30 mg/L和300 mg/L时,经过生物接触氧化处理,出水含油量和COD分别降至1 mg/L和50 mg/L以下,达到了反渗透膜组件预处理的要求,为稠油污水热采锅炉用水回用提供了理论基础。     

甲苯在硝酸盐还原条件下的生物降解性能研究

通过对长期受石油污染的土著微生物进行培养驯化,得到适于降解甲苯的优势混合菌,并对其在硝酸盐还原条件下降解甲苯的件能进行研究.结果表明,驯化所得甲苯降解菌的最适降解条件为:温度25℃,pH值7.5,C/N值15,接种量1%.混合降解菌对硝态氮的去除符合一级动力学特征,其降解速率常数为0.0021 mg/(L·h).采用非...     

PVA降解菌的复配组合及其紫外诱变处理的研究

对已筛选出的4株PVA降解菌进行不同的组合后测定PVA降解率,发现Z5与Z8菌株混合后在1周内对PVA的去除率达到了所有组合中的最高值52.07%,比单菌株提高了约22%。采用紫外照射的方法对混合菌进行诱变并利用正交实验研究其特性,结果表明,诱变后的混合菌在1周内降解了91.46%的PVA,并且碳源浓度对酶活的影响最为显著。当pH为7,碳源、氮源含量分别为1.5 g/L、0.6 g/L,NaC l浓度为1.5 g/L时,诱变菌株处于最佳生长状态。     

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。     

Anaerobic biodegradation of methyl tert-butyl ether under iron-reducing conditions in batch and continuous-flow cultures.

The feasibility of biodegradation of the fuel oxygenate methyl tert-butyl ether (MTBE) under iron-reducing conditions was explored in batch and continuous-flow systems. A porous pot completely-mixed reactor was seeded with diverse cultures and operated under iron-reducing conditions. For batch studies, culture from the reactor was transferred anaerobically to serum bottles containing either MTBE alone or MTBE with ethanol (EtOH) and excess electron acceptor. In the continuous-flow reactor, MTBE conversion to tert-butyl alcohol (TBA) was observed after 181 days of operation, and stable removal was achieved throughout the remainder of the study. Simultaneously, both the MTBE only and the MTBE and EtOH iron-reducing batch serum bottles also began to degrade MTBE. Bottles were respiked and the degradation rate was determined to be 2.36 +/- 0.10 x 10(-4) mmol MTBE/min-kgVSS. The EtOH present with MTBE degraded faster (7.76 +/- 0.08 x 10(-3) mmol EtOH/min-kg VSS) but did not have a noticeable effect on the rate of MTBE degradation. No evidence of TBA degradation was observed by the iron-reducing cultures. Stoichiometry of iron utilization was determined from the iron balance of the continuous-flow reactor, and it was found that the bulk of the electron acceptor was required for energy and maintenance with little remaining for cell synthesis. This is consistent with a yield coefficient of less than 0.1. Molecular analysis of the iron-reducing culture by denaturing gradient gel electrophoresis indicated that uncultured strains of delta-Proteobacteria were dominant in the reactor.     

Persistence of methyl <Emphasis Type="Italic">tertiary</Emphasis> butyl ether (MTBE) against metabolism by Danish vegetation

BACKGROUND: Methyl tertiary butyl ether (MTBE) is the second most highly produced industrial chemical in the US and a frequent groundwater pollutant. At the same time, MTBE is quite persistent to biotic and abiotic decomposition. The goal of this study was to find plant species that could degrade MTBE and might be used in phytoremediation. METHODS: Excised roots and leaves (0.3 g) from more than 24 Danish plant species out of 15 families were kept in glass vessels with 25 ml spiked aqueous solution for 2 to 4 days. MTBE concentrations were 1 to 5 mg/L. Samples were taken directly from the solution with a needle and injected to a purge and trap unit. MTBE and the main metabolite, TBA, were measured by GC/FID. RESULTS AND DISCUSSION: Solutions with roots of poplar (Populus robusta) and a willow hybrid (Salix viminalis x schwerinii) produced TBA in trace amounts, probably stemming from bacteria. Significant MTBE reduction (> 10%) was not observed in any of the tests. Leaves from none of the species (trees, grasses and herbs) reduced the concentration of MTBE in the solution and no TBA, nor any other known metabolite of MTBE, was detected. CONCLUSION: It was not possible to find plants capable of efficiently degrading MTBE. This gives rise to the conclusion that plants probably cannot degrade MTBE at all, or only very slowly. RECOMMENDATIONS AND OUTLOOK: For phytoremediation projects, this has, as consequence, that the volatilization by plants (except with genetically engineered plants) is the only relevant removal process for MTBE. For risk assessment of MTBE, degradation by the plant empire is not a relevant sink process.     

Influences of metals on kinetics of methyl tert-butyl ether biodegradation by Ochrobactrum cytisi

The influence of zinc, manganese, and nickel on the degradation of MTBE (methyl tert-butyl ether), by an aerobic MTBE-degrading strain, Ochrobactrum cytisi, were investigated. The result showed that unlike previous findings, O. cytisi was able to degrade MTBE through direct metabolism when MTBE was present as the only carbon source. The degradation rate of MTBE was rapid, completed within 80 h. MTBE biodegradation by this strain was stimulated at low concentrations of Zn(2+) (1-5 mg l(-1)) and Mn(2+) (1-5 mg l(-1)) but inhibited at high concentrations of Zn(2+) (20 mg l(-1)) and Mn(2+) (20 mg l(-1)), and at low concentration of Ni(2+) (1-4 mg l(-1)). Kinetic parameters for MTBE degradation in the presence or absence of metals were obtained through nonlinear regression and a least-square minimization procedure. In all cases, a good agreement was achieved between kinetic simulations and experimental results.     

Laboratory evidence of MTBE biodegradation in Borden aquifer material

Mainly due to intrinsic biodegradation, monitored natural attenuation can be an effective and inexpensive remediation strategy at petroleum release sites. However, gasoline additives such as methyl tert-butyl ether (MTBE) can jeopardize this strategy because these compounds often degrade, if at all, at a slower rate than the collectively benzene, toluene, ethylbenzene and the xylene (BTEX) compounds. Investigation of whether a compound degrades under certain conditions, and at what rate, is therefore important to the assessment of the intrinsic remediation potential of aquifers. A natural gradient experiment with dissolved MTBE-containing gasoline in the shallow, aerobic sand aquifer at Canadian Forces Base (CFB) Borden (Ontario, Canada) from 1988 to 1996 suggested that biodegradation was the main cause of attenuation for MTBE within the aquifer. This laboratory study demonstrates biologically catalyzed MTBE degradation in Borden aquifer-like environments, and so supports the idea that attenuation due to biodegradation may have occurred in the natural gradient experiment. In an experiment with batch microcosms of aquifer material, three of the microcosms ultimately degraded MTBE to below detection, although this required more than 189 days (or >300 days in one case). Failure to detect the daughter product tert-butyl alcohol (TBA) in the field and the batch experiments could be because TBA was more readily degradable than MTBE under Borden conditions.     

高效生物活性炭吸附工艺去除水体中甲基叔丁基醚的初步研究

通过对来自美国加州拉玛达(La Mirada)市污染点的原始菌源炭进行甲基叔丁基醚(MTBE)降解菌生物强化,试图建立具有更有效MTBE降解效果的生物活性炭(BAC)功能,尝试利用新形成的菌源炭覆盖新鲜椰壳活性炭(GAC)而达到新BAC功能的快速有效启动,并考察不同空床停留时间(EBCT)、GAC吸附饱和状态对BAC功能启动的影响。同时,对具有成熟BAC功能的炭柱中的混合菌落进行基于16SrDNA的聚合酶链反应(PCR)—变性梯度凝胶电泳(DGGE)分析,以确定混合菌落中的主要功能菌种属。结果表明,针对模拟的低MTBE浓度进水,新鲜GAC和菌源炭A添加体积分数分别为40%和60%的NAS柱出水MTBE质量浓度最终稳定低于0.005mg/L,平均去除率接近99%,出水MTBE完全达到美国环境保护署(EPA)的饮用水建议阈值(<20μg/L),建立了成熟的BAC功能;成熟的菌源炭可在30d左右通过覆盖法迅速实现新BAC功能的启动;EBCT的延长有利于新BAC功能的启动和维持,接种初期应尽量采用较长EBCT以保证取得足够和稳定的生物量;MTBE吸附饱和前后的GAC在启动新BAC功能时存在差异,鉴于吸附饱和GAC在接种初期会因MTBE解吸而造成出水MTBE浓度较高,建议采用新鲜活性炭覆盖需接种炭柱;BAC功能成熟炭柱中包括的5种主要菌种里有4种为未培养微生物,1种为未分类菌种,其理化性质和具体属性尚不明确。     

植物混种原位修复多环芳烃污染农田土壤

通过比较实验前后土壤微生物主要类群数量、PAHs降解菌数量、土壤PAHs含量和植物不同部位PAHs含量变化,评价植物单种和混种野外原位修复多环芳烃(PAHs)污染农田土壤的效果。结果显示,150 d天生长期内,黑麦草/小麦混种及黑麦草/蚕豆混种修复效果最好,对土壤PAHs总量的降解率分别达到了59.4%和64.8%。同时,这2个混种处理土壤细菌、真菌和PAHs降解菌数量分别显著高于相应的小麦、蚕豆和黑麦草单种处理。植物不同部位PAHs含量高低次序为根部>茎叶≈籽粒。混种模式下,蚕豆和小麦不同部位PAHs含量比单种模式的不同程度降低,特别是籽粒部。植物混种模式不仅显著提高了土壤PAHs的降解率,还降低了农作物体内PAHs含量,实现了边生产边修复,在污染农田土壤修复领域有着广阔的应用前景。     

Enrichment and isolation of endosulfan degrading and detoxifying bacteria

In the present study, degradation of endosulfan by a mixed culture isolated from a pesticide-contaminated soil was studied in batch experiments. After two weeks of incubation, the mixed culture was able to degrade 73% and 81% of alpha and beta endosulfan respectively. Endodiol was identified by GC/MS as degradation intermediate. The toxicity studies of endosulfan before and after degradation were carried out using micronucleus assay on human polymorphonuclear cells. The findings suggested that the metabolism of endosulfan isomers by the mixed culture was accompanied by significant reduction in the toxicity. Studies were also carried out to quantify the degradation potential of the individual species in the mixed bacterial culture. Two cultures identified by 16S rRNA as Stenotrophomonas maltophilia and Rhodococcus erythropolis were found to be responsible for majority of the degradation by the mixed culture. S. maltophilia showed better degradation efficiency compared to that by R. erythropolis. This is the first report of endosulfan degradation using the above-mentioned organisms.     

The Use of Stable Isotopes to Differentiate Specific Source Markers for MTBE

The recent controversy over the use of MTBE within gasoline to boost oxygen content and decrease carbon monoxide emissions to the atmosphere has led to a proposed phase-out of this compound by 2002. This paper is a preliminary investigation into the use of gas chromatography isotope-ratio mass spectrometry (GCIRMS) to determine both carbon and hydrogen isotopic compositions of MTBE as a means of differentiating sources of MTBE. Three pure MTBE samples were purchased from chemical distributors. Little variation of the δ¹³C values were observed although the samples had isotopically distinct δ-D values. Four different methods of obtaining carbon isotope ratios of neat MTBE, MTBE in gasoline, and MTBE in water are described, and the precision and accuracy of each is discussed. The carbon isotopic compositions of MTBE within 10 gasoline samples from three different areas of the United States show a wide range of carbon isotope compositions. This novel method of MTBE analysis could be valuable in forensic investigations.     

The Use of Stable Isotopes to Differentiate Specific Source Markers for MTBE

The recent controversy over the use of MTBE within gasoline to boost oxygen content and decrease carbon monoxide emissions to the atmosphere has led to a proposed phase-out of this compound by 2002. This paper is a preliminary investigation into the use of gas chromatography isotope-ratio mass spectrometry (GCIRMS) to determine both carbon and hydrogen isotopic compositions of MTBE as a means of differentiating sources of MTBE. Three pure MTBE samples were purchased from chemical distributors. Little variation of the i 13 C values were observed although the samples had isotopically distinct i -D values. Four different methods of obtaining carbon isotope ratios of neat MTBE, MTBE in gasoline, and MTBE in water are described, and the precision and accuracy of each is discussed. The carbon isotopic compositions of MTBE within 10 gasoline samples from three different areas of the United States show a wide range of carbon isotope compositions. This novel method of MTBE analysis could be valuable in forensic investigations.     

Aerobic degradation of diuron by aquatic microorganisms

Abstract

Degradation of diuron [3‐(3,4‐dichlorophenyl)‐l,1‐dimethyl‐urea] by microorganisms obtained from pond water and sediment was determined under aerobic conditions. Enrichment procedures were used to isolate cultures capable of degrading the herbicide. Several mixed fungal/bacterial and mixed bacterial cultures were isolated that could degrade diuron. The mixed cultures degraded 67–99% of the added diuron forming from six to seven products which were separated via TLC. The major degradation product detected in most culture extracts was 3,4‐dichloroaniline. Other identified products formed were 3‐(3,4‐dichlorophenyl)‐1‐methylurea and 3‐(3,4‐dichlorophenyl)urea.