两种缓释肥料在海水中的养分释放特性及强化石油烃生物降解

通过沙土柱实验考察了硫包衣尿素和甲醛尿素2种缓释肥料在不同pH值和盐度的海水介质中养分的释放特性,并利用摇瓶培养实验考察了这两种肥料对SZ36-1原油生物降解作用的影响.结果表明,在实验设置的pH(7.00-8.00)和盐度(24.00-32.00)范围内,pH值对硫包衣尿素和甲醛尿素肥料氮素释放性能有较大影响,其中,近中性的海水介质有利于硫包衣尿素中氮素的释放,弱碱性环境更有利于甲醛尿素的释放;而盐度对两种肥料的氮素释放均无明显影响.两种缓释肥料都能够持续释放氮素而维持石油烃降解菌QPH-2的生长,并促进原油中各组分包括烷烃和芳烃明显降解.其中,添加硫包衣尿素体系中各烷烃组分的降解率为13.94%-59.02%,芳烃类组分降解率为9.60%-32.33%;添加甲醛尿素体系中各烷烃组分的降解率为11.56%-49.65%,芳烃类组分降解率为13.49%-41.67%.     

生物表面活性剂对铜绿假单胞菌摄取烷烃的强化机制

考察了2株铜绿假单胞菌(Pseudomonasaeruginosa)以正十六烷为底物生长的不同方式,并初步探讨了生物表面活性剂在烃类降解菌摄取烷烃过程中的作用机制.菌株O-2-2在正十六烷中的生长明显快于PS-1,生长过程中O-2-2分泌出鼠李糖脂生物表面活性剂,正十六烷被完全乳化.另外,O-2-2菌细胞表面疏水性高于PS-1,而加入鼠李糖脂使得菌体细胞中脂多糖含量减少,菌细胞表面疏水性明显提高.上述结果表明,鼠李糖脂主要通过乳化疏水性底物和提高降解菌表面疏水性两种机制强化铜绿假单胞菌(P.aeruginosa)对烷烃的摄取.图6表1参14     

微杆菌3-28对萘、菲、蒽、芘的降解

研究了以多环芳烃为唯一碳源富集培养的微杆菌3-28对不同多环芳烃化合物(Polycyclic aromatichydrocarbons,PAHs)及混合PAHs的降解能力,以及在无机基础培养基中生长时PAHs浓度与一些主要环境因子如pH值、盐度、温度对细菌降解PAHs的影响.结果表明,微杆菌3-28X对萘、菲、蒽和芘均有较高的降解能力,112 h后萘与菲完全降解,而蒽和芘28 d的降解率分别为97.54%、90.2%.初始底物浓度会影响细菌生长速率,底物浓度过高不利于细菌生长.相同培养时间下多底物培养液中的菌群浓度明显高于单底物系统.微杆菌3-28能够在pH 6.0-9.0、盐度10～30g/kg,温度40～55℃的环境下生存,并保持较高的降解能力.图8参33     

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%。     

烷烃降解菌的筛选、鉴定及优势菌株的降解特性

以正庚烷为唯一碳源,从长期受到石油污染的土壤中筛选获得可利用正庚烷的微生物14株.通过形态观察和16S rDNA序列比对,鉴定G2、G9、G14为红球菌属,G3、G27为人苍白杆菌属,G4、G7为芽孢杆菌属,G5、G10、G15、G25为节杆菌属,G16为缺陷短波单胞菌,G17、G22为嗜麦芽寡养单胞菌属.通过考察其降解烷烃的能力,确定Rhodococcus sp.G2为烷烃降解优势菌株.该菌株可代谢庚烷获得最大菌体浓度D600 nm=7.51.同时该菌对不同碳链长度的烷烃,如十二烷、十六烷、煤油和二甲苯均具有较强的降解能力,以十二烷为碳源的最大比生长速率为0.37 h-1,最高菌体浓度为D600 nm=12.00,在正十六烷中生长,最大比生长速率为0.23 h-1,在煤油中生长,最大比生长速率为0.14 h-1,在以二甲苯为唯一碳源时,D600 nm也可达到1.00左右.研究表明该菌株对于石油污染土壤的生物修复有很大的应用前景.图6表2参9     

北京市道路空气中非甲烷烃的分布特征

利用气相色谱对北京市几种典型道路空气中非甲烷烃(NMHCs)的浓度进行了监测,讨论了道路空气中非甲烷烃的浓度分布特征.结果表明,北京市各种典型道路空气中非甲烷烃浓度都呈双峰形,分别在早晨8:00左右和下午5:00左右,车流量是影响非甲烷烃浓度的最主要因素,狭窄道路空气中的非甲烷烃浓度要明显高于十字路口和平直道路的非甲烷烃浓度.     

产生物表面活性剂的石油降解菌Acinetobacter BHSN的研究

从石油污染土壤中分离筛选获得1株产生物表面活性剂的石油降解菌株BHSN.经形态观察、生理生化试验、16S rDNA 序列分析等将其鉴定为不动杆菌属(Acinetobacter sp.).研究表明,BHSN菌株能降解石油中C13～C32正构烷烃.BHSN菌株生长和产生物表面活性剂的最适温度为25～30 ℃,最适pH为5.0～8.5.LB培养基中添加终质量浓度为10 g·L-1葡萄糖能促进菌体的生长,但不利于表面活性剂的合成;添加蔗糖、乳糖、麦芽糖和木糖对菌体的生长和表面活性剂的合成均有促进作用,其中麦芽糖的促进作用最强.初步研究表明,BHSN菌株产的生物表面活性剂为脂肽类;BHSN发酵液的表面张力由初始68.3 mN·m-1降低到28.6 mN·m-1.     

土壤中石油污染物微生物修复动力学和机理初探

以正十六烷为代表污染物,研究2种微生物对烷烃的反应动力学方程,以及正十六烷的摄取和运输机理;确定吸附摄取和运输对整个代谢过程的影响.结果表明,降解菌对正十六烷均有一定的运输富集能力;2株菌对正十六烷的运输过程存在很大差别,DQ01对正十六烷的运输呈缓慢趋势,而DQ02对正十六烷的主动运输过程是比较快的.菌体对正十六烷的吸附和运输过程对于正十六烷的降解速度影响较小,限制污染物降解速率和程度的关键可能是降解过程.     

曝气生物滤池处理采油废水过程中有机物的降解

在曝气生物滤池(BAF)系统中,按水力停留时间(HRT)4h,对盐度为0.5% (W/V)的采油废水进行处理,并利用GC-MS对废水中有机物的构成进行分析,结果表明:采油废水中有机污染物的主要构成是9种支链烷烃和18种直链烷烃,分布范围从正十三烷(C13H28)到正三十二烷(C32H66).由于降解中间产物的累积,出水中烷烃类物质所占比例降低,而芳香族物质比例上升.在采油废水中烷烃的存在下, PAHs中最易被微生物降解的是含有4个苯环、脂溶性强的,降解效率达98.0%;而降解效果最差的为含有二个苯环、脂溶性较差的萘,降解效率仅为66.4%.     

天津地区表层土中饱和烃的组成与分布特征

为揭示天津地区不同环境功能区表层土壤中饱和烃污染特征及其来源,分析了该地区几个具代表性的环境功能区表层土(0～25cm)中饱和烃化合物的组成和分布特征,重点讨论了正构烷烃和甾、萜烷烃类化合物的组成、分布及环境意义,比较了不同层次(亚层)(0～5cm,5～10cm,10～15cm,15～20cm,20～25cm)中这些化合物及相关的地球化学参数的变化规律。结果表明,不同采样点以及同一采样点的不同亚层之间正构烷烃的组成特征存在不同程度的差别,而甾、萜烷烃类化合物组成与分布特征均较为接近。正构烷烃以及甾、萜类地球化学参数综合分析揭示,不同采样点之间正构烷烃的来源多样,中低分子量的正构烷烃主要来源于石油等化石燃料,高分子量正构烷烃主要来源于高等植物蜡的分解产物,但甾、萜烷烃类化合物的来源是一致的,且主要来源于石油烃污染。不同采样点表层土中饱和烃的来源及污染程度均存在一定的差别,市区、油田附近、经济开发区以及近郊区受石油源影响较重,北部山区污染较轻,且主要来源于高等植物的降解。除个别采样点外,同一采样点不同亚层之间饱和烃的组成特征基本一致,表明污染源是一致的,主要来源由表层污染物往下迁移所致。     

产表面活性剂降解石油菌株产物性质及降解性能研究

微生物是组成生态系统的重要成员,在污染物去除中发挥着重要作用,是生物修复中的主力,然而在石油污染修复过程中,石油烃的疏水性会限制微生物对石油的降解,但一些微生物的细胞代谢物即生物表面活性剂,它是微生物在一定条件下代谢分泌产生的具有一定表面活性,集亲水基和疏水基结构于一分子的两亲性化合物,可以促进油的乳化,提高油的分散程度,增大菌株和油珠的接触机会,促进对石油烃的吸收和降解。在实验室分离得到了7株产表面活性剂石油降解菌株,经分子鉴定可知菌1和菌2都为粘质沙雷氏菌Serratia marcescens,菌3为居植物柔武氏菌Raoultella planticola,菌4,菌6和菌7都为克雷伯氏菌Klebsiella variicola,菌5为蜡状芽孢杆菌Bacillus cereus。主要研究了它们的生长与表面活性剂物质分泌状况的关系,发现随着时间增加,OD值随之增大,表面张力呈现下降趋势;并对菌株产物进行提取和薄层层析,离子型分析和红外光谱分析,初步判断其产物均为阴离子糖脂类;通过pH,初始油质量浓度,接种量和盐度4个单因素的变化研究菌1粘质沙雷氏菌,菌3居植物柔武士菌,菌5蜡状芽孢杆菌和菌6克雷伯氏菌对石油类物质降解能力,发现菌3居植物柔武氏菌和菌5蜡状芽孢杆菌降解性能较好;通过响应曲面法优化蜡状芽孢杆菌的降解条件,得出其最佳降解条件为pH为5.02,油质量浓度为3 g·L-1,接种量为1199.98μL,盐度为0.5 g·L-1时,在此条件下,菌株对石油的降解率为66.94%。     

Transmembrane transport of polycyclic aromatic hydrocarbons by bacteria and functional regulation of membrane proteins

• Explaintheadsorption, uptake and transmembrane transport of PAHs by bacteria. • Analyze functional regulation of membrane proteins inthe transmembrane transport. • Proteomics technology such as iTRAQ labeling was used to access expressed proteins. • Single cell analysis technology wereused to study the morphological structure. In recent years, increasing research has been conducted on transmembrane transport processes and the mechanisms behind the microbial breakdown of polycyclic aromatic hydrocarbons (PAHs), including the role of membrane proteins in transmembrane transport and the mode of transmission. This article explains the adsorption, uptake and transmembrane transport of PAHs by bacteria, the regulation of membrane protein function during the transmembrane transport. There are three different regulation mechanisms for uptake, depending on the state and size of the oil droplets relative to the size of the microbial cells, which are (i) direct adhesion, (ii) emulsification and pseudosolubilization, and (iii) interfacial uptake. Furthermore, two main transmembrane transport modes are introduced, which are (i) active transport and (ii) passive uptake and active efflux mechanism. Meanwhile, introduce the proteomics and single cell analysis technology used to address these areas of research, such as Isobaric tags for relative and absolute quantitation (iTRAQ) technology and Nano Secondary ion mass spectrometry (Nano-SIMS). Additionally, analyze the changes in morphology and structure and the characteristics of microbial cell membranes in the process of transmembrane transport. Finally, recognize the microscopic mechanism of PAHs biodegradation in terms of cell and membrane proteins are of great theoretical and practical significance for understanding the factors that influence the efficient degradation of PAHs contaminants in soil and for remediating the PAHs contamination in this area with biotechnology.     

Degradation rates of aged petroleum hydrocarbons are likely to be mass transfer dependent in the field

Evidence for on site biodegradation may be difficult to provide at heterogeneous sites without additional experiments in controlled laboratory conditions. In this study, microbial activities measured as CO₂ and CH₄ production were compared in situ, in intact soil cores and in bottle microcosms containing sieved soils. In addition, biodegradation rates were determined by measuring the decrease in petroleum hydrocarbon concentrations at 7°C in aerobic and anaerobic conditions. Elevated concentrations of CO₂ and CH₄ in the soil gas phase indicated that both the aerobic and anaerobic microbial activity potentials were high at the contaminated site. Aerobic and anaerobic microbial degradation rates in laboratory experiments of petroleum hydrocarbons were highest in soils from the most contaminated point and degradation in the aerobic and anaerobic microcosms was linear throughout the incubation, indicating mass-transfer-dependent degradation. Different results for microbial activity measurements were obtained in laboratory studies depending on pretreatment and size of the sample, even when the environmental conditions were mimicked. These differences may be related to differences in the gas exchange rates as well as in changes in the bioavailability of the contaminant in different analyses. When predicting by modeling the behavior of an aged contaminant it is relevant to adapt the models in use to correspond to conditions relevant at the contaminated sites. The variables used in the models should be based on data from the site and on experiments performed using the original aged contaminant without any additions.     

Microbial community and functional genes in the rhizosphere of alfalfa in crude oil-contaminated soil

A rhizobox system constructed with crude oil-contaminated soil was vegetated with alfalfa (Medicago sativa L.) to evaluate the rhizosphere effects on the soil microbial population and functional structure, and to explore the potential mechanisms by which plants enhance the removal of crude oil in soil. During the 80-day experiment, 31.6% of oil was removed from the adjacent rhizosphere (AR); this value was 27% and 53%higher than the percentage of oil removed from the far rhizosphere (FR) and from the non-rhizosphere (NR), respectively. The populations of heterotrophic bacteria and hydrocarbon-degrading bacteria were higher in the AR and FR than in the NR. However, the removal rate of crude oil was positively correlated with the proportion of hydrocarbon-degrading bacteria in the rhizosphere. In total, 796, 731, and 379 functional genes were detected by microarray in the AR, FR, and NR, respectively. Higher proportions of functional genes related to carbon degradation and organic remediation, were found in rhizosphere soil compared with NR soil, suggesting that the rhizosphere selectively increased the abundance of these specific functional genes. The increase in water-holding capacity and decrease in pH as well as salinity of the soil all followed the order of AR>FR>NR. Canonical component analysis showed that salinity was the most important environmental factor influencing the microbial functional structure in the rhizosphere and that salinity was negatively correlated with the abundance of carbon and organic degradation genes.     

石油污染与微生物群落结构的相互影响

从两种土壤中分别分离出石油烃降解菌,并从中筛选出6株石油烃高效降解菌A1、A2、A6、A8和B2及B5,然后将各菌株鉴定至属,分别为A1假单胞菌属、A2鞘氨醇单胞菌属、A6微球菌属、A8节杆菌属、B2不动杆菌属和B5诺卡氏菌属。另外对比分析了单菌株及不同菌株重组对不同石油烃组分的利用情况,结果发现,从不同石油污染的土壤中分离到的菌株对石油烃组分的利用能力不同,从胜利原油污染的土壤中分离到的菌株A1、A2、A6和A8对石油烃组分的利用范围窄,主要利用饱和烃组分;而从经芳香烃驯化过的土壤中分离到的菌株B2及B5对石油烃利用组分的利用范围较宽,能同时利用饱和烃和芳香烃组分。     

植物-微生物修复石油烃污染土壤与根际微生态环境变化

石油烃作为一类持久性难降解有机污染物对土壤环境质量产生严重的危害。以天津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靶细胞,以小麦、紫花苜蓿作为供试植物,利用盆栽试验,对植物-外源菌协同修复体系中的脱氢酶活性和土壤微生物多样性进行研究,分析其变化及其与石油烃降解率的关系。结果表明植物-微生物协同修复对石油烃具有较好的降解能力,其中小麦-固定化外源菌组具有最高的降解率,石油烃含量从最初的30 600 mg獉kg-1下降为24 300 mg獉kg-1,降解率为20.6%,并且其试验后期石油烃的降解率最大,远远高于其他时期,表现出良好的修复潜力。外源菌投加的初始阶段会迅速提高脱氢酶活性,然而这种影响随着降解时间延长而逐渐减弱。初期脱氢酶活性与总石油烃的降解存在较好的相关性,脱氢酶活性可以在一定程度上表征土壤石油烃的降解情况。微生物多样性与总石油烃降解也存在一定的相关性。     

Characteristics of arsenic accumulation by the seaweeds Fucus spiralis and Ascophyllum nodosum

This study examines the accumulation of ⁷⁴As-arsenic in the seaweeds Fucus spiralis (L.) and Ascophyllum nodosum (L.) collected from Restronguet Creek in southwest England during 1978. Also, the influence of environmental factors (valence state of arsenic, pH, salinity, temperature, phosphate concentration) and metabolic inhibitors on the uptake of arsenic by F. spiralis is examined. Most of the arsenic in the seaweeds was non-exchangeable with labelled arsenic in the medium. The accumulation of ⁷⁴As reached a steady state in 1 to 8 d, depending on the species and external arsenic concentration. At steady state the accumulated arsenic is proportional to external arsenate concentration. F. spiralis accumulated 4 times more arsenate than arsenite. The short-term uptake of arsenic increased in proportion to the external arsenic concentration up to a level of 1000 g l^-1; it then remained constant at higher levels of arsenic. Arsenic uptake increased in direct proportion to increasing temperature. Variation of pH or salinity had no effect on arsenic incorporation. The accumulation of arsenic occurred only in living tissue and was inhibited by KCN in a concentration-dependent manner. The uptake of arsenic by F. spiralis in the presence of photo-synthetic inhibitors (DCMU or CMU) or in the dark was greater than in the light controls. Thus, it was concluded that energy is required for arsenic uptake and this is derived from respiration rather than photosynthesis. There was no evidence for a common mechanism of phosphate and arsenate uptake by macroalgae, although high concentrations of phosphate (40 to 400 M) initially inhibited arsenate uptake.     

Effects of salinity on the net uptake of zinc by the common mussel Mytilus edulis

The net uptake of zinc by the common mussel Mytilus edulis (L.) has been investigated under different natural and artificial salinity stresses. The effects of stable and fluctuating salinities on the uptake of zinc by the mussel are discussed in terms of three possible modes of action. Under certain highly-stressful conditions, salinity may affect the uptake of zinc by the mussel. This factor should be considered when the mussel is used as an indicator of environmental pollution by zinc in estuarine areas, or spurious conclusions may result.     

Bioremediation of highly contaminated oilfield soil: Bioaugmentation for enhancing aromatic compounds removal

This study evaluated the effectiveness of different amendments--including a commercial NPK fertilizer, a humic substance （HS）, an organic industrial waste （NovoGro）, and a yeast-bacteria consortium--in the remediation of highly contaminated （up to 6% of total petroleum hydrocarbons） oilfield soils. The concentrations of hydrocarbon, soil toxicity, physicochemical properties of the soil, microbial population numbers, enzyme activities and microbial community structures were examined during the 90-d incubation. The results showed that the greatest degradation of total petroleum hydro- carbons （TPH） was observed with the biostimulation using mixture of NPK, HS and NovoGro, a treatment scheme that enhanced both dehydrogenase and lipase activities in soil. Introduction of exogenous hydrocarbon-degrading bacteria （in addition to biostimulation with NPK, HS and NovoGro） had negligible effect on the removal of TPH, which was likely due to the competition between exogenous and autochthonous microorganisms. None- theless, the addition of exogenous yeast-bacteria consor- tium significantly enhanced the removal of the aromatic fraction of the petroleum hydrocarbons, thus detoxifying the soil. The effect of bioaugmentation on the removal of more recalcitrant petroleum hydrocarbon fraction was likely due to the synergistic effect of bacteria and fungi.     

Responses of microbial interactions to elevated salinity in activated sludge microbial community

● Salinity led to the elevation of NAR over 99.72%. ● Elevated salinity resulted in a small, complex, and more competitive network. ● Various AOB or denitrifiers responded differently to elevated salinity. ● Putative keystone taxa were dynamic and less abundant among various networks. Biological treatment processes are critical for sewage purification, wherein microbial interactions are tightly associated with treatment performance. Previous studies have focused on assessing how environmental factors (such as salinity) affect the diversity and composition of the microbial community but ignore the connections among microorganisms. Here, we described the microbial interactions in response to elevated salinity in an activated sludge system by performing an association network analysis. It was found that higher salinity resulted in low microbial diversity, and small, complex, more competitive overall networks, leading to poor performance of the treatment process. Subnetworks of major phyla (Proteobacteria, Bacteroidetes, and Chloroflexi) and functional bacteria (such as AOB, NOB and denitrifiers) differed substantially under elevated salinity process. Compared with subnetworks of Nitrosomonadaceae, Nitrosomonas (AOB) made a greater contribution to nitrification under higher salinity (especially 3%) in the activated sludge system. Denitrifiers established more proportion of cooperative relationships with other bacteria to resist 3% salinity stress. Furthermore, identified keystone species playing crucial roles in maintaining process stability were dynamics and less abundant under salinity disturbance. Knowledge gleaned from this study deepened our understanding of microbial interaction in response to elevated salinity in activated sludge systems.