芘高效降解菌ZQ5的培养条件及无机元素对其降解效率的影响

以从我国最大的石油污水灌区之一——沈抚灌区污染土壤分离到的以芘为惟一碳源、能源生长的高效降解菌株ZQ5为实验材料,通过对菌株ZQ5培养条件的优化,以及采用摇瓶振荡培养方法测定菌株ZQ5对不同浓度芘的降解率,表明:菌株ZQ5在30℃振荡培养16 d后对150 mg/L芘的降解率为90.31%。通过模拟稻田施用N、P和K肥等的土壤环境,探索了无机营养元素对降解菌ZQ5降解能力的影响,发现土壤中混合加入N、P和K无机营养元素的降解率能达到82%以上,比单加某种营养元素对降解菌ZQ5的降解效果好。本研究结果可以指导稻田PAHs的原位生物修复。     

降解菌ZQ5与紫茉莉对芘污染土壤的联合修复

在温室盆栽条件下,通过单独种植紫茉莉、单独接种多环芳烃(PAHs)模式化合物芘的专性降解菌ZQ5和两者的联合修复的3种处理,对芘污染土壤的修复效果进行了研究。结果表明,经90 d修复后,植物-微生物联合修复可将人工污染土壤中的芘降解81.1%,将石油污染土壤中的芘降解50.3%,其修复效率明显高于其他2种处理,是紫茉莉修复的1.98倍,是降解菌ZQ5修复的1.39倍。ZQ5的不同接菌量对于修复60 d后的降解率影响不大。外源生物修复条件下,10～20 cm土壤的修复效率要高于5 cm土壤;自然降解条件下,5 cm土层降解率略高于其他土层。     

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.     

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。     

一株芘降解菌B2的降解条件优化及降解基因

芳香烃降解菌是石油污染土壤修复的主要生物资源。采用芘平板升华法对克拉玛依原油污染土壤样品进行驯化培养,分离得到一株芘降解菌B2,经16S rDNA基因序列比对及系统发育进化分析表明,该菌株为假单胞菌属(Pseudo-monas)。采用正交设计方法优化菌株B2对高分子量多环芳烃芘的降解条件,并构建多元非线性模型预测菌株B2对芘的最佳降解条件,结果表明:在接种量OD660 nm为0.60、降解温度为40℃、降解时间为6.0 d时,预测菌株B2对芘的降解最大达到38.214 mg/L,实际测得最大降解量为37.906 mg/L,预测准确率为99.19%。运用PCR技术克隆B2的邻苯二酚-2,3-双加氧酶基因(B2C23O)(I.2.A亚家族),核酸序列分析表明,该基因全长880 bp,具有一个完整的开放阅读框,编码246个氨基酸,与已报道的Pseudomonas putida W619同源性最高为97%;对B2C23O基因编码氨基酸序列进行分析,发现其具有邻位断裂双加氧酶模式结构,推测菌株B2通过邻位裂解途径降解芘代谢中间产物邻苯二酚。     

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。     

芘降解菌DY-1的条件优化及降解动力学特性分析

选用已筛选出以芘为唯一碳源的假单胞菌DY-1(Pseudomonas sp.)作为芘降解菌,采用摇瓶振荡培养方法,研究了不同环境条件对菌DY-1降解芘效率的影响以及降解动力学特性。结果表明,在含芘50 mg/L的条件下培养9 d,降解率达83.2%。最适宜温度为30℃,pH值为7.5,摇床转速为120 r/min,接种量为1.5 mL;在不同培养条件下芘的降解符合一级动力学模型;低浓度Zn2+,Cd2+,Cr6+的存在对芘降解效果影响较小,Cu2+,Pb2+对芘的降解有较强的毒性;加入低浓度有机物质,蔗糖可提高DY-1芘的降解;低浓度萘或蒽的存在可促进芘的降解。     

多环芳烃降解菌菌群构建及其适宜降解环境条件的确定

利用富集培养技术从某焦化厂土壤中筛选出来的菌种,根据3种不同的配伍方式构成3种不同的菌群。以苯并[a]芘、苯并[a]蒽、苯并[b]荧蒽、苯并[k]荧蒽和茚并[1,2,3-cd]芘5种多环芳烃为唯一碳源的无机盐培养基,不同菌群降解效率均达到60%以上。模拟多环芳烃污染的土壤环境,利用正交实验对菌群组合、菌量等因素不同水平探索降解的适宜条件。降解14 d的适宜条件为组合二:菌量20%、温度30℃、土壤含水率15%、营养盐质量比(m(C)∶m(N)∶m(P))为120∶10∶1、表面活性剂500 mg·kg-1、Fenton试剂和植物油2.5%;降解28 d的适宜条件为组合三:菌量10%、温度30℃、土壤含水率15%、m(C)∶m(N)∶m(P)为100∶10∶1、表面活性剂1 000 mg·kg-1、Fenton试剂和植物油5%;降解52 d的适宜条件为组合三:菌量20%、温度20℃、土壤含水率35%、m(C)∶m(N)∶m(P)为120∶10∶1、表面活性剂500 g·kg-1、Fenton试剂和植物油为0。m(C)∶m(N)∶m(P)随着降解时间的延长影响作用逐渐减小。在降解的整个阶段,菌群组合的类型对于降解率的影响最大。对于降解14 d时,菌群组合二为最优菌群,对于降解28和52 d时,菌群组合三为最优菌群。     

邻苯二酚-2,3-双加氧酶基因在芘降解菌基因组的整合与表达

为了构建能够稳定遗传且高效降解多环芳烃的工程菌,利用PCR技术对Pseudomonas songnenensis wp3-1的邻苯二酚-2, 3-双加氧酶(C23O)基因进行克隆,并将其与自杀性载体pUTmini-Tn5连接,得到重组载体pUTmini-Tn5-C23O。在三亲接合作用下,经mini-Tn5转座子将重组载体pUTmini-Tn5-C23O中的C23O基因整合到菌株Pseudomonas sp. wp4的染色体DNA中,最终得到基因工程菌wp4-C23O。在不同pH、温度下,菌株wp4和工程菌wp4-C23O对浓度为50 mg?L-1的芘进行降解7 d。2株菌降解最适温度为37℃、最适pH为7.5。在此条件下,工程菌wp4-C23O对芘降解率显著高于wp4菌株(P0.05),降解率提高11.45%。以PAHs降解优势菌株为受体构建工程菌可以去除石油污染土壤中的PAHs。     

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。     

油污土中降解柴油细菌的分离鉴定及降解能力研究

从所采集柴油污染土壤样品中富集、分离得到柴油降解优势菌株,命名为B-3和B-4.根据其生理生化性质及16S rDNA序列比对分析,确定2株菌分别属于Tetrathiobacter kashmirensis、假单胞菌属(Pseudomonas sp.).由于实验中,B-3的生长曲线较特殊,故以B-3和典型石油烃降解菌假单...     

Biodegradation of triazine herbicide metribuzin by the strain Bacillus sp. N1

By enrichment culturing of soil contaminated with metribuzin, a highly efficient metribuzin degrading bacterium, Bacillus sp. N1, was isolated. This strain grows using metribuzin at 5.0% (v/v) as the sole nitrogen source in a liquid medium. Optimal metribuzin degradation occurred at a temperature of 30ºC and at pH 7.0. With an initial concentration of 20 mg L^?1, the degradation rate was 73.5% in 120 h. If the initial concentrations were higher than 50 mg L^?1, the biodegradation rates decreased as the metribuzin concentrations increased. When the concentration was 100 mg L^?1, the degradation rate was only 45%. Degradation followed the pesticide degradation kinetic equation at initial concentrations between 5 mg L^?1 and 50 mg L^?1. When the metribuzin contaminated soil was mixed with strain N1 (with the concentration of metribuzin being 20 mg L^?1 and the inoculation rate of 10¹¹ g^?1 dry soil), the degradation rate of the metribuzin was 66.4% in 30 days, while the degradation rate of metribuzin was only 19.4% in the control soil without the strain N1. These results indicate that the strain N1 can significantly increase the degradation rate of metribuzin in contaminated soil.     

A two-stage process using electrokinetic remediation and electrochemical degradation for treating benzo[a]pyrene spiked kaolin

An innovative process that combines soil electrokinetic remediation and liquid electrochemical oxidation for the degradation of organic compounds present in a polluted soil was developed and evaluated by using benzo[a]pyrene spiked kaolin. In order to increase benzo[a]pyrene solubility during electrokinetic treatment, the addition of a co-solvent or surfactant, such as ethanol or Brij 35, as flushing solution was tested. The research carried out demonstrated the influence of the desorption agent employed on benzo[a]pyrene remediation from the kaolin matrix. Thus, if the flushing solution was ethanol at 40%, there was no presence of contaminant in either chamber. On the contrary, when a solution of surfactant Brij 35 was used, benzo[a]pyrene was transported towards the cathode chamber, where it was collected. Moreover, the extent of this recovery depends on the pH profile on the soil. When no pH control was used, around 17% of initial contaminant was detected in the cathode chamber; however, when pH control was applied, the recovery of benzo[a]pyrene could be higher than 76%, when the pH control in the anode chamber was set at 7.0.In order to obtain the total degradation of mobilised benzo[a]pyrene from the contaminated soil, the liquid collected by electrokinetic remediation was oxidised by electrochemical treatment. This oxidation was accomplished via an electrochemical cell with a working volume of 0.4 L, and graphite as electrode material. The benzo[a]pyrene was almost totally degraded in 1 d, reaching a degradation of about 73% in 16 h.     

Influence of root-exudates concentration on pyrene degradation and soil microbial characteristics in pyrene contaminated soil

The effect of ryegrass (Lolium perenne L.) root-exudates concentration on pyrene degradation and the microbial ecological characteristics in the pyrene contaminated soil was investigated by simulating a gradually reducing concentration of root exudates with the distance away from root surface in the rhizosphere. Results showed that, after the root-exudates were added 15 d, the pyrene residue in contaminated soil responded nonlinearly in the soils with the same pyrene contaminated level as the added root-exudates concentration increased, which decreased first and increased latter with the increase of the added root-exudates concentration. The lowest pyrene concentration appeared when the root exudates concentration of 32.75 mg kg(-1) total organic carbon (TOC) was added. At the same time, changes of microbial biomass carbon (MBC, C(mic)) and microbial quotient (C(mic)/C(org)) were opposite to the trend of pyrene degradation as the added root-exudates concentration increased. Phospholipid fatty acid (PLFA) analysis revealed that bacteria was the dominating microbial community in pyrene contaminated soil, and the changing trends of pyrene degradation and bacteria number were the same. The changing trend of endoenzyme-dehydrogenase activity was in accordance with that of soil microbe, indicating which could reflect the quantitative characteristic of detoxification to pyrene by soil microbe. The changes in the soils microbial community and corresponding microbial biochemistry characteristics were the ecological mechanism influencing pyrene degradation with increasing concentration of the added root-exudates in the pyrene contaminated soil.     

Influence of environmental factors on degradation of carbendazim by Bacillus pumilus strain NY97-1

The influence of environmental factors on the performance of carbendazim degradation by Bacillus pumilus strain NY97-1 was investigated under aerobic conditions. The carbendazim degradation in culture medium was characterised by High-Performance Liquid Chromatography (HPLC) with UV detector. When the initial concentration of carbendazim was 10, 30, 50, 100, 300 mg/L, the degradation rate was 42.44, 48.97, 77.19, 78.66 and 90.07%, respectively after 24 h at 30°C. Addition of small amount of organic nitrogenous source had a significant influence on carbendazim degradation, while the inorganic nitrogenous source had negative effect. Carbendazim degradation rate varied from 61.55% to 87.76% when pH value within the range of 4–10 after addition of organic nitrogen, the lowest carbendazim degradation percentage of 61.55% was obtained at pH 4.     

Co-metabolic degradation of naphthalene and pyrene by acclimated strain and competitive inhibition kinetics

A dominant strain named Ochrobactrum sp. was isolated from soils contaminated with coal tar. The batch experiments were carried out to study the co-metabolic degradation of pyrene by Ochrobactrum MB-2 with naphthalene as the main substrate and the effects of several significant parameters such as naphthalene concentration, pH and temperature on removal efficiency were explored. The results showed that Ochrobactrum MB-2 effectively degraded naphthalene and that the addition of naphthalene favored the degradation of pyrene. The maximum elimination efficiency of naphthalene (10?mg?L^?1) and pyrene (1?mg?L^?1) was achieved at pH 7 and 25?°C, and the corresponding values were 99 and 41%, respectively. A competitive inhibition model based on the Michaelis–Menten equation was used to characterize the inhibitory effect of pyrene on naphthalene degradation. The values of the half-saturation coefficient for naphthalene (K_S) and dissociation constant of enzyme-inhibitor complex (K_C) were determined to be 4.93 and 1.38?mg?L^?1, respectively.     

Isolation and characterization of a newly isolated pyrene-degrading Acinetobacter strain USTB-X

The pryene-degradation bacterium strain USTB-X was newly isolated from the polycyclic aromatic hydrocarbon (PAH)-contaminated soil in Beijing Coking Plant, China. The strain was identified as Acinetobacter with respect to its 16S rDNA and morphological and physiological characteristics. The strain was Gram-negative, non-mobile, non-acid-fast, and non-spore-forming, short rods in young culture and 0.8–1.6 μm in diameter and 1.2–2.5 μm long in the stationary phase of growth. Strain USTB-X could utilize pyrene, naphthalene, fluorene, phenanthrene, benzene, toluene, ethylbenzene, ethanol, methanol, and Tween 80 as sole source of carbon and energy. The strain could produce biosurfactants which enhanced the removal of pyrene and could remove 63 % of pyrene with an initial concentration of 100 mg·L^?1 in 16 days without other substrates. Based on the intermediates analyzed by gas chromatography-mass spectrometry, we also deduced the possible metabolic pathway of strain USTB-X for pyrene biodegradation. Results indicated that the strain USTB-X had high potential to enhance the removal of PAHs in contaminated sites.     

Biodegradation of polycyclic aromatic hydrocarbons by a mixed culture

We investigated the potential biodegradation of polycyclic aromatic hydrocarbons (PAHs) by an aerobic mixed culture utilizing phenanthrene as its carbon source. Following a 3-5 h post-treatment lag phase, complete degradation of 5 mg/l phenanthrene occurred within 28 h (optimal conditions determined as 30 degrees C and pH 7.0). Phenanthrene degradation was enhanced by the individual addition of yeast extract, acetate, glucose or pyruvate. Results show that the higher the phenanthrene concentration, the slower the degradation rate. While the mixed culture was also capable of efficiently degrading pyrene and acenaphthene, it failed to degrade anthracene and fluorene. In samples containing a mixture of the five PAHs, treatment with the aerobic culture increased degradation rates for fluorene and anthracene and decreased degradation rates for acenaphthene, phenanthrene and pyrene. Finally, it was observed that when nonionic surfactants were present at levels above critical micelle concentrations (CMCs), phenanthrene degradation was completely inhibited by the addition of Brij 30 and Brij 35, and delayed by the addition of Triton X100 and Triton N101.