降解聚丁二酸丁二醇酯菌株的诱变选育及降解性能

诱变选育是基因资源开发的重要手段之一,为了对降解聚丁二酸丁二醇酯(PBS)菌株的降解性能进行改良,选择具有一定降解PBS能力的尖孢镰刀菌(Fusarium oxysporum)DSCF-8为出发菌株,分别研究了其在5种诱变途径下的突变效应及最佳诱变条件,测定了突变菌株D8B14在不同条件下的降解性能。结果表明,复合诱变途径的高效降解菌株获得率大于单因子诱变途径,分别达到了4.55%和1.30%,但突变株的降解特性遗传不稳定;硫酸二乙酯单因子诱变效应大于紫外线诱变和微波诱变,且得到的突变株较复合诱变得到的菌株具有更强的遗传稳定性,最佳诱变条件为5%的浓度处理40 min。硫酸二乙酯诱变得到的突变株D8B14传代稳定且降解性能优异,其对PBS薄膜的降解率较出发菌株提高了34.49%,粗酶液酶活性提高率为23.86%。该突变株在35℃条件下仍表现出较高的降解能力,对不同的初始pH条件亦具有更强的耐受能力,尤其在pH 4.0或pH 9.0的酸性和碱性条件下,降解率分别提高了13.26%和27.04%。     

厌氧菌群JAC1降解石油烃能力及其群落结构的解析

利用苯酚诱导获得厌氧菌群JAC1强化去除土壤中的石油烃，对其在厌氧条件下的石油烃降解条件进行了优化，得到最适降解条件为：pH 7.5～8.5,土壤总石油烃(TPH)质量浓度50 mg/kg, NaCl质量分数0.3%,JAC1接菌量0.15 mL/g。厌氧菌群JAC1对石油烃的降解符合一级动力学模型。通过气相色谱质谱联用仪分析，芳香烃较直链烷烃更难降解，推测部分长链烷烃在降解过程中会分解为短链烷烃后再进行降解。基于土壤宏基因组测序分析可知，土壤微生物群落多样性与TPH浓度呈负相关，投加JAC1后土壤中与石油烃降解有关的功能菌群相对丰度呈现出不同程度增高，说明JAC1有助于建立一个高效的微生物降解体系来强化石油烃降解。     

不同植物-微生物联合修复体系下石油烃的降解

石油烃作为环境中广泛存在的有机污染物之一,对人体健康造成严重的危害。以位于天津的大港油田原油污染土壤中筛选出的耐低温高效石油烃降解菌为供试菌株,以小麦、紫花苜蓿作为供试植物,比较不同类型植物以及不同的外源菌接种方式对石油降解的影响,并采用荧光素比色法分析荧光素二乙酸酯(FDA)酶活性随时间的变化规律。经过70 d的降解,原状土壤的总石油烃含量从30 720 mg·kg~(-1)下降为26 800 mg·kg~(-1),降解率为12.76%。相比于小麦,紫花苜蓿对石油烃的降解具有更好的促进效果,降解率为24.85%。接种菌悬液后再种植植物时,石油烃降解效果接近于单独接种菌悬液处理。小麦-固定化外源菌处理条件下,降解率为21.10%,实验后期石油烃的降解速率远远高于其他处理,表现出良好的修复潜力。FDA酶活性经历了先下降、后上升再下降直至平缓的过程,并且受到种植植物和投加外源菌的影响。     

3种石油烃降解菌对石油烃的降解效果及其细胞表面疏水性

选取3种石油烃降解菌:假单胞菌(Pseudomonas sp.,DS-1)、铜绿色假单胞菌(Pseudomonas aeruginosa,DS-2)和无色杆菌(Achromobacter sp.,DS-3),研究其对石油烃的降解效果及其细胞表面疏水性。结果表明,经过6d的降解,3种石油烃降解菌对石油烃的降解率分别为99.08%、79.75%、84.34%。石油烃的黏附性测试和盐析聚集测试结果表明,3种石油烃降解菌均表现出较高的细胞表面疏水性,其规律为DS-1DS-3DS-2。其中DS-1的细胞表面疏水性最高,达65.90%。DS-1、DS-2和DS-3菌株发生盐析聚集所需最小(NH4)2SO4摩尔浓度分别为2.0、2.8、2.4 mol/L。菌株的细胞表面疏水性和降解有机物的能力有着较高的相关性。     

石油污染土壤中高效石油烃降解菌Y-16的筛选及其降解性能

通过富集和驯化培养从石油污染的土样中筛选出一株高效石油烃降解菌Y-16,其对胜利原油7 d降解率达到51.98%。在好氧条件下,对Y-16菌株的最优降解条件进行了探索,结果表明,在pH值8.0,温度30℃,接种量10%,摇床转数160 r/m in和3 000~7 000 mg/L的底物浓度下,Y-16菌株的最高降解率可达到60.34%。通过Y-16菌株对石油烃降解规律的探索,发现Y-16菌株对石油烃的降解符合一级反应动力学模型。     

两种石油烃降解菌的鉴定及其对石油烃底物的降解

采用16SrDNA技术对石油污染场地筛选出的两种单菌(A6菌和A10菌)进行鉴定,并对两种单菌及其混合菌降解石油烃各组分的效果进行了研究。结果表明,两种单菌分别为假单胞菌(Pseudomonas sp.)和无色杆菌(Achromobacter sp.)。两种单菌及其混合菌对石油烃的降解有所差异,其降解效果依次为混合菌A6菌A10菌。其中A6菌和A10菌对石油烃底物降解的组分大致相同,两者均能完全降解大部分直链烷烃、环烷烃和支链烷烃,部分降解C9~C27正构烷烃。从降解程度来看,A6菌优于A10菌。两种单菌的混合菌在降解石油烃底物时,具有协同降解作用,对石油烃底物降解的组分及降解程度均优于两种单菌;混合菌除了能完全降解大部分直链烷烃、环烷烃和支链烷烃外,还对A6菌和A10菌不能彻底降解的支链烷烃(3,8-二甲基癸烷和2-甲基-十二烷)完全降解。     

利用不同组分原油逐级驯化筛选高效石油烃降解混菌

利用不同组分原油逐级驯化的方法对克拉玛依油田的石油污染土样进行石油烃降解混菌的富集驯化,得到一组对稀油和稠油均具有高效降解能力的混菌M3。与采用单一原油驯化方法相比,混菌M3对稀油和稠油的降解率分别提高了12.5%和22%。该混菌具有较强的产表面活性剂的能力,能够使发酵液的表面张力从69.8 mN·m~(-1)降至27.9 mN·m~(-1)。通过混菌M3的生长条件优化实验得出:在温度30℃、pH 7～8、盐度1%、氮源选择尿素的条件下,混菌M3对原油的降解率最高。通过考察混菌M3在污染土壤中对原油的降解效果,发现:在修复期间,土壤脱氢酶呈先升高后降低的趋势;混菌M3可使饱和烃组分增加,并使芳香分、胶质和沥青质组分降低,对重质组分具有较好的降解效果。混菌M3的加入改变了原油性质,促进了土壤中原油的降解,经过56 d修复,土壤中原油降解率达到55.3%。     

石油降解菌群的筛选、构建及其降解特性研究

为了构建高效石油降解混合菌群,从潜江某油田采集8个石油污染土样(分别记为S1~S8)和2个石油污染水样(分别记为W3、W4),以石油为唯一碳源进行富集驯化培养;采用外观评分、石油降解率、石油3组分降解率、饱和烃中正构烷烃色谱分析等方法筛选石油降解优势菌群,构建石油降解混合菌群;采用正交试验研究混合菌群最佳降解条件。结果表明,富集的10个石油降解菌群中S3、S4、S5、S6、S8为优势菌群,培养30d后的石油降解率分别为21.67%、22.34%、27.23%、20.46%、19.99%;菌群W3、W4对石油乳化效果较好;混合菌群M3(S3+S4+S5+S8+W3+W4)为石油降解优势混合菌群,其最佳降解条件为35℃、pH7.60、含油率1.70%,在最佳条件下培养30d后,混合菌群M3对石油降解率达30.71%,比最优菌群S5的石油降解率提高了12.78%。     

石油降解菌的筛选优化及其对油污土壤的修复特性

分别以牛肉膏蛋白胨-布氏哈斯培养基、蓝色凝胶培养基作为初筛和复筛培养基,从石油污染土壤中筛选出2株可产生微生物表面活性剂的石油烃降解菌。并将菌株投加到油污土壤中进行修复研究,考查了不同影响因素对修复效果的影响。研究结果表明,(1)2株菌对中度石油污染土壤有较好的修复效果,向油污土壤中直接投加菌株修复70 d时对石油烃的去除率为52%;(2)向油污土壤中投加降解菌并同时补充氮营养液,修复70 d时对土壤中总石油烃的去除率可达到75%;对土壤中正构烷烃的去除率为66%;(3)与土壤的含水率及土著菌的降解效果相比,向油污土壤中投加降解菌以及补充氮磷营养液是影响石油污染土壤修复效果的关键因素。     

用于石油污染土壤降解的高效降解菌的筛选及其降解条件优化

经过富集、分离优选出高效石油降解菌L-1,根据形态观察和生理生化特征初步鉴定为琼氏不动杆菌;采用单因素花盆实验模拟微生物原位修复并对其降解条件进行优化。结果表明,将高效石油降解菌应用于修复石油污染土壤,适宜接种量、表面活性剂浓度、CNP比、翻耕频率分别为15%、0.1%、100∶10∶1和1 d 1次;在该降解条件下修复28 d,可达到16.80%的石油降解率,远远高于土著微生物6.92%的降解率。     

Effect of biochar on the fate of volatile petroleum hydrocarbons in an aerobic sandy soil

Biochar addition to soil is currently being investigated as a novel technology to remediate polluted sites. A critical consideration is the impact of biochar on the intrinsic microbial pollutant degradation, in particular at sites polluted with a mixture of readily biodegradable and more persistent organic pollutants. We therefore studied the impact of biochar (2% on dry weight basis) on the fate of volatile petroleum hydrocarbons in an aerobic sandy soil with batch and column studies. The soil-water partitioning coefficient, K(d), was enhanced in the biochar-amended soil up to a factor 36, and petroleum hydrocarbon vapor migration was retarded accordingly. Despite increased sorption, in particular of monoaromatic hydrocarbons, the overall microbial respiration was comparable in the biochar-amended and unamended soil. This was due to more rapid biodegradation of linear, cyclic and branched alkanes in the biochar amended soil. We concluded that the total petroleum hydrocarbon degradation rate was controlled by a factor other than substrate availability and the reduced availability of monoaromatic hydrocarbons in the biochar amended soil led to greater biodegradation of the other petroleum compounds.     

强化生物通风修复过程中柴油衰减规律及其影响因素研究

强化生物通风技术对于修复因地下储油罐泄漏引起的土壤污染具有很大的应用前景。通过室内土柱模拟柴油泄漏污染土壤，从土柱中总石油烃（total petroleum hydrocarbon，TPH）剖面分布随时间的变化及降解模式角度，分析了其自然衰减和强化生物通风过程。结果表明：初始柴油浓度直接影响着各柱在自然衰减和强化生物通风过程中柱内的残余TPH平衡分布曲线的形状和浓度峰值位置；在前期自然衰减过程中（约1个月），当土壤中的柴油浓度为5 000～40 000 mg油/kg土时，整个柱内TPH变化的主要原因是重力扩散迁移的结果；当土壤中的柴油浓度≤5 000 mg油/kg土时，其TPH的变化不仅是重力扩散迁移作用的结果，生物降解作用也存在；通风约2个月后，抽提作用对于保持土柱上部柴油浓度稳定变化的意义较为突出。     

Comparative toxic and genotoxic effects of chloroacetanilides,formamidines and their degradation products on Vibrio fischeri and Chironomus riparius

Toxic and genotoxic effects of alachlor, metolachlor, amitraz, chlordimeform, their respective environmentally stable degradation products 2,6-diethylaniline, 2-ethyl-4-methylaniline, 2,4-dimethylaniline, and two other related compounds, 3,4-dichloroaniline and aniline were compared. Acute toxicity tests with Chironomus riparius (96 h) and Vibrio fischeri (Microtox) and genotoxicity tests with a dark mutant of V. fischeri (Mutato) were carried out. Our results demonstrate that toxicity and genotoxicity of the pesticides are retained upon degradation to their alkyl-aniline metabolites. In the case of the herbicides alachlor and metolachlor, the toxicity to V. fischeri was enhanced upon degradation. Narcosis alone explains toxicity of the compounds to the midge, but not so for the bacteria suggesting a disparity in the selectivity of the test systems. All compounds showed direct genotoxicity in the Vibrio test. but amitraz and its metabolite were genotoxic at concentrations 10(3)-10(5) lower than all the other compounds. The observations indicate that stable aniline degradation products of the pesticides may contribute considerably to environmental risks of pesticides application and that genotoxic effects may arise upon degradation of pesticides.     

Assessment of a process to degrade metal working fluids using Pseudomonas stutzeri CECT 930 and indigenous microbial consortia

The development of a novel biological process to treat metal working fluids (MWFs)-containing effluents at bioreactor scale was pursued in this work. The bacteria Pseudomonas stutzeri CECT 930 was investigated for the first time as an alternative agent for MWF degradation. An adequate medium design and mixing and aeration system, as well as an appropriate microorganism proved to be crucial for reaching high levels of degradation by P. stutzeri and by an indigenous consortium (about 70% and 50% of reduction in total petroleum hydrocarbon content in less than 2 wk, respectively). Additionally, as there is no information in literature trying to kinetically characterize an MWF-polluted effluent degradation process, all the experimental data were fitted to logistic and Luedeking and Piret models, that allowed to elucidate the growth-associated character of the biodegradation process.     

Bioremediation of oil-contaminated soil using Candida catenulata and food waste

Even though petroleum-degrading microorganisms are widely distributed in soil and water, they may not be present in sufficient numbers to achieve contaminant remediation. In such cases, it may be useful to inoculate the polluted area with highly effective petroleum-degrading microbial strains to augment the exiting ones. In order to identify a microbial strain for bioaugmentation of oil-contaminated soil, we isolated a microbial strain with high emulsification and petroleum hydrocarbon degradation efficiency of diesel fuel in culture. The efficacy of the isolated microbial strain, identified as Candida catenulata CM1, was further evaluated during composting of a mixture containing 23% food waste and 77% diesel-contaminated soil including 2% (w/w) diesel. After 13 days of composting, 84% of the initial petroleum hydrocarbon was degraded in composting mixes containing a powdered form of CM1 (CM1-solid), compared with 48% of removal ratio in control reactor without inoculum. This finding suggests that CM1 is a viable microbial strain for bioremediation of oil-contaminated soil with food waste through composting processes.     

土壤石油烃污染的植物毒性及植物-微生物联合降解

通过盆栽实验研究了土壤石油烃污染对玉米和水稻根伸长的影响，并在土壤中接种经过筛选得到的石油烃降解菌，研究石油烃降解菌对石油烃毒性的影响以及对土壤中石油烃的降解。研究结果表明，石油烃浓度低于1 000 mg/kg时对玉米的根系生长有一定的刺激生长作用，随着石油烃浓度的增加，刺激根长生长的作用逐渐降低，研究结果表明，水稻根长受石油烃影响较小。通过对不同处理土壤中石油烃降解的研究结果表明，土壤中种植水稻对石油烃有一定的降解作用，但是不同处理下土壤中的石油烃降解率不同，其中水稻微生物联合处理下土壤中石油烃的降解速率最快，培养期内的降解效率达到53.3%。     

紫外活化过硫酸盐工艺降解水中磺胺二甲氧嘧啶动力学特征与机理

采用紫外活化过硫酸盐(UV/PS)工艺降解典型磺胺类抗生素磺胺二甲氧嘧啶(SDM),比较单一紫外(UV)、单一过硫酸盐(PS)和UV/PS对SDM的去除效果,考察各因素对降解动力学的影响,并探究其降解机理,对SDM及其中间产物进行毒性测定和风险评价.结果显示,UV/PS可以加速SDM降解,反应速率常数分别是单一UV和单...     

Ecorisk evaluation and treatability potential of soils contaminated with petroleum hydrocarbon-based fuels

We used a series of toxicity tests to monitor oil degradation in the Kuwaiti oil lakes. Three soils from different locations with a history of hydrocarbon contamination were treated in bench-scale microcosms with controlled nutrient amendments, moisture content, and temperature that had promoted mineralization of total hydrocarbon and oil and grease in a preliminary study. Two hundred days of bioremediation treatment lowered hydrocarbon concentration to below 2 and 5 mg g(-1) for soils A and B, respectively, while in soil C hydrocarbon concentration remained at 12 mg g(-1). Although 85% of the total petroleum hydrocarbons (TPHs) in soil A were reduced 50d after treatment, results of the seed germination and Microtox tests suggested an initial increase in toxicity, indicating that toxic intermediary metabolites may have formed during biodegradation. Also, the significant decrease of TPHs and corresponding high toxicity levels were noted in soil B 200d after bioremediation. Clearly, toxicity values, and not just hydrocarbon concentration, are a key factor in assessing the effectiveness of bioremediation techniques. Field chemistry data showed a significant reduction in hydrocarbon levels after the biological treatment. We concluded that the toxicity assessment of the contaminated soil with a battery of toxicity bioassays could provide meaningful information regarding a characterization procedure in ecological risk assessment.     

Age-dating Diesel Fuel Spills: Using the European Empirical Time-based Model in the U.S.A.

In 1993, a paper was published by Christensen and Larsen that offered a method for determining the age of diesel oil spills in soil (Christensen and Larsen, 1993 Ground Water Mount. R . Fall , 142-149). It presented an empirical time-based model of the degradation of diesel fuel in soils using chemical data gathered at petroleum release sites in Denmark and the Netherlands. Now, evaluation of the validity of the application of this work to subsurface petroleum releases in other countries remains. In the U.S.A., investigations assessing date(s) of release of diesel fuel in soils, e.g. age dating of subsurface petroleum contamination, have considerable interest. Litigation-driven scientific investigations with accompanying expert testimony in a court of law are underway. The number of instances where application of the Christensen and Larsen empirical time-based model to petroleum-contaminated properties is growing in the U.S.A. This paper presents two case studies which evaluate the applicability of the Christensen and Larsen empirical time-based model to petroleum-contaminated properties in general. It illustrates the approach using gas chromatographic data from two recently-completed projects evaluating the applicability of the Christensen and Larsen model to a No. 2 fuel oil/diesel fuel surface spill in the U.S.A. Results showed that the application of the model to petroleum-contaminated soils was scientifically valid, provided its applicability was evaluated using hypothesis testing for specific changes in the characteristics of the petroleum hydrocarbon distribution in a number of soil samples collected over time at one site. The paper offers observations on the application of the Christensen and Larsen model to petroleum found in the light non-aqueous phase liquid (LNAPL) phase and groundwater.     

Phytoremediation of petroleum hydrocarbons in tropical coastal soils II. microbial response to plant roots and contaminant

Goal, Scope and Background.  The goal of this study was to understand the interaction between plants and microorganisms during petroleum-hydrocarbon bioremediation in Pacific Islands coastal soils. Total bacteria and hydrocarbon-degrading microorganisms population dynamics were examined in the rhizospheres of tropical trees and shrubs, which were evaluated for their phytoremediation potential in a greenhouse experiment. The respective and combined effects of plant roots and diesel contaminant on the microbial populations were determined in relation to diesel fuel depletion. An increase in the size of the hydrocarbon-degrading populations of microbes, elicited by rhizodeposition, is generally regarded as conducive to an enhanced degradation of petroleum hydrocarbon polutants in veaetated soil. Conclusion  The results suggest the quality of the rhizodeposition is plant-dependent and governs the type of diesel-degrader populations that will be enhanced by a given plant. Recommendations and Outlook  In the proposed phytoremediation-benefit model plant roots maintain high levels of hydrocarbon de-graders in uncontaminated soil. When the root enters a contaminated zone of soil, those hydrocarbon degraders that prefer the contaminant would switch to the contaminant as a carbon source, effectively removing the hydrocarbons. If the root exudates and the contaminant are equally attractive to the hydrocarbon degraders, the contaminant degradation would be less effective.