多环芳烃降解真菌Fusarium solani对芘的吸收存储和降解特性研究

以芘为唯一碳源,从公路旁污染土壤中分离得到一株芘降解真菌,经鉴定为Fusarium solani(命名为Py F-1),荧光显微镜观察发现其菌丝能吸收储存芘.对该菌株在芘浓度为50 mg·L-1的液体培养基中对芘的吸收储存和降解特性,具体包括芘的生物降解、菌体吸收、菌体吸附和消解总量进行了39 d的动态研究,结果表明:生物降解芘在培养0~14 d内逐渐增加,培养14 d时占芘添加量的15.9%,此后基本达到稳定,培养结束时生物降解芘为芘添加量的17.6%;菌体吸收芘在0~21 d内含量较少且变化不显著,低于芘添加量的3%;而在21~39 d内,菌体吸收芘变化显著,芘的消解总量随着菌体吸收量的变化产生显著波动;培养28 d时,芘的消解总量达到最大值,其中菌体吸收芘占芘消解总量的一半,达到芘添加量的16.0%,菌体吸附芘不足芘添加量的0.5%,在研究中可以忽略不计.因此,培养前期培养基中芘的消解以生物降解为主,培养后期菌体吸收芘的变化是芘消解总量变化的主要原因.     

多环芳烃在全土及其碱提残余物上的吸附行为

以菲和芘为代表性化合物,采用8种有机质含量不同的天然全土样品及其碱提残余物进行吸附实验,并利用不同吸附模型进行数据拟合,藉以探讨有机质含量对土壤吸附行为的影响.结果表明,Freundlich吸附模型的非线性指数n都小于1,显示全土和碱提残余物在多环芳烃的吸附过程中表现出非线性特征.菲和芘的吸附行为随土壤有机质含量不同而变化,碱提残余物的吸附能力强于全土,两者吸附行为的差异主要归因于土壤有机质含量和性状的区别.     

苯并(a)芘及其代谢产物的连续降解研究

在以驯化过的芽孢杆菌(BA-07)降解BaP的过程中,鉴定出2个BaP的未开环代谢产物顺式-4,5-二氢-4,5-二醇-BaP(cis-BP4,5-dihydrodiol)和顺式-7,8-二氢-7,8-二醇-BaP(cis-BP7,8-dihydrodiol).由于该产物对微生物有一定毒性,所以难于进一步降解.为提高BaP降解的同时,降低cis-BP4,5-dihydrodiol和cis-BP7,8-dihydrodiol的累积,对2种降解方法(即单纯用BA07降解和运用高锰酸钾与BA-07耦合的方法降解)进行了比较,并且优化了连续降解的参数.结果表明,①对BaP及其代谢产物的连续降解,化学氧化与微生物耦合(高锰酸钾与BA-07)的降解效果明显好于单纯利用微生物(细菌BA-07)的降解;②在同一时间取样,cis-BP4,5-dihydrodiol的残留率均高于cis-BP7,8-dihydrodiol;③当BaP的浓度为40μg/mL,培养基的最佳pH为7.0,以琥珀酸钠为共代谢底物,可以显著提高BaP降解率,降低cis-BP 4,5-dihydrodiol和cis-BP7,8-dihydrodiol的累积.同时提出了化学氧化与微生物协同的方法可以有效促进环境中持久有机污染物的连续降解.     

Silica nanoparticles and silver-doped silica nanoparticles induce endoplasmatic reticulum stress response and alter cytochrome P4501A activity

Engineered silica nanoparticles (SiO₂-NPs) find widespread application and may lead to exposure of humans and the environment. Here we compare the effects of SiO₂-NPs and SiO₂-NPs doped with silver (SiO₂-Ag-NPs) on survival and cellular function of human liver cells (Huh7) and Pimephales promelas (fathead minnow) fibroblast cells (FMH). In Huh7 cells we investigate effects on the endoplasmatic reticulum (ER), including ER stress, and interactions of nanoparticles (NPs) with metabolizing enzymes and efflux transporters. The NPs formed agglomerates/aggregates in cell culture media as revealed by SEM and TEM. SiO₂ and SiO₂-1% Ag-NPs were taken up into cells as demonstrated by agglomerates occurring in vesicular-like structures or freely dispersed in the cytosol. Cytotoxicity was more pronounced in Huh7 than in FMH cells, and increased with silver content in silver-doped NPs. Dissolved silver was the most significant factor for cytotoxicity. At toxic and non-cytotoxic concentrations SiO₂-NPs and SiO₂-1% Ag-NPs induced perturbations in the function of ER. In Huh7 cells NPs induced the unfolded protein response (UPR), or ER stress response, as demonstrated in induced expression of BiP and splicing of XBP1 mRNA, two selective markers of ER stress. Additionally, SiO₂-1% Ag-NPs and AgNO₃ induced reactive oxygen species. Pre-treatment of Huh7 cells with SiO₂-1% Ag-NPs followed by exposure to the inducer benzo(a)pyrene caused a significant reduced induction of CYP1A activity. NPs did not alter the activity of ABC transporters. These data demonstrate for the first time that SiO₂-NPs and SiO₂-1% Ag-NPs result in perturbations of the ER leading to the ER stress response. This represents a novel and significant cellular signalling pathway contributing to the cytotoxicity of NPs.     

Can Hediste diversicolor (Nereidae, Polychaete) be considered a good candidate in evaluating PAH contamination? A multimarker approach

The aim of this study was to develop a preliminary characterization of the biological responses of Hediste diversicolor to polycyclic aromatic hydrocarbons (PAHs) under controlled laboratory conditions. In order to test the effects of PAH exposure, a battery of biomarkers was applied to the polychaetes by exposing them to sublethal concentrations of benzo[a]pyrene (0.1 and 0.5 mg L⁻¹) for 10 d under laboratory conditions. The battery of biomarkers tested included oxidative stress biomarkers (glutathione content, enzymatic activities of catalase, glutathione S-transferases, glutathione reductase, glutathione peroxidases), total oxyradical scavenging capacity (TOSC) toward peroxyl and hydroxyl radicals and activity of acyl CoA oxidase (AOX) as a marker of peroxisome proliferation measured in the entire body; lipofuscin and neutral lipid accumulations and levels of Ca²⁺-ATPase activity analyzed in the intestinal epithelium; lysosomal membrane stability and genotoxic effects measured as DNA strand breaks and frequency of micronuclei in coelomocytes. Chemical analyses were also carried out to verify the polychaete’s benzo[a]pyrene (B[a]P) bioaccumulation levels after the exposure period. The results obtained indicate that B[a]P caused significant changes in most of the parameters measured in H. diversicolor. Biological responses to the organic compound were particularly significant for the biomarkers measured in the intestinal epithelium and in coelomocytes, emphasizing that these tissues were more affected during our experimental conditions. Considering the key trophic role of this benthic species in estuarine and coastal ecosystems, this study confirmed that H. diversicolor is an appropriate bioindicator of organic contamination.     

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。     

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。     

地表水超痕量苯并(a)芘的检测及空白干扰消除

采用液液萃取-超高效液相色谱仪接荧光检测器测定地表水中超痕量的苯并(a)芘,并对方法空白的干扰因素进行探讨。研究发现,该法的空白干扰主要来自于溶剂二氯甲烷,溶剂经蒸馏提纯后可消除干扰。以重新蒸馏提纯的二氯甲烷为提取剂,方法的检测限为0.05 ng/L,加标回收率为87.4%~132%,且空白测定值低于方法检出限,可满足地表水中超痕量苯并(a)芘检测的需求。     

六株真菌对土壤中芘和苯并芘的降解及其动力学

研究了6株真菌对土壤中芘和苯并芘(BaP)的降解动态,用Michaelis-Menton和Monod动力学模型对结果进行拟合.结果表明,6株真菌对芘和BaP的降解速率有显著性差异,降解率相差不大.产黄青霉(Penicillium chrysogenum,SF04),在42d内对BaP的降解能力最强,可达71.31%,对芘的降解能力相对最弱.镰刀菌(Fusariumsp.,SF11),黑曲霉(Aspergillusniger,SF05),木霉(Trichodermasp.,SF02)和毛霉(Mucorsp.,SF06)42d对芘的降解率分别为86.22%,86.18%,85.41%,85.04%,对BaP的降解率分别为71.11%,69.44%,69.05%,69.72%.木霉(Trichodermasp.,SF02)和毛霉(Mucorsp.,SF06)对芘和BaP的降解速率均很快.