一株多环芳烃芘降解菌的鉴定及其降解特性研究

从红树植物红海榄叶片中分离一株对芘具有较好降解作用的海洋细菌,命名为B11,并对其菌体特征、生长条件及降解效能等进行了系统研究。结果发现该菌株为革兰氏阴性菌,结合其生理生化特征和16S rDNA序列比对,表明此菌株属于交替单胞菌属(Alteromonas sp.)。菌株在芘的起始浓度为100 mg/L,pH为中性或偏碱性条件下,盐度35时对芘的降解作用最强。外加碳源对B11对芘的降解效果都具有一定的抑制作用,其中水杨酸的抑制作用更为显著。综合菌株B11的生长特性和降解效能,初步认为B11菌株较适合用于降解多环芳烃芘,可用于红树植物多环芳烃生态污染的原位修复。     

Induction of cytochrome P4501A and biliary PAH metabolites in European eel Anguilla anguilla: Seasonal, dose- and time-response variability in field and laboratory conditions

Induction of cytochrome P4501A in fish is a well-known indicator of exposure to polycyclic aromatic hydrocarbons (PAHs) and determination of PAH metabolites in bile by fixed wavelength fluorescence (FF) or synchronous fluorescence spectroscopy (SFS), has become an useful method in monitoring programs. In this work the relationship between cytochrome P4501A (EROD activity) and levels of biliary PAH metabolites was measured in the European eel Anguilla anguilla, in both field and laboratory conditions: organisms were sampled on a seasonal basis from the Orbetello lagoon (Tuscany) to characterize the natural variability of these biological parameters, while in laboratory eels were intraperitoneally injected with benzo[a]pyrene to investigate temporal and dose-dependent induction patterns. Results showed that induction of cytochrome P450 and accumulation of PAHs metabolites in bile are not necessarily correlated either in field, or in laboratory investigations; different seasonal changes were measured in natural conditions and slight variations in dose and time response patterns were also obtained in laboratory exposures.     

Comet assay for the detection of genotoxicity in blood cells of flounder (Paralichthys olivaceus) exposed to sediments and polycyclic aromatic hydrocarbons

To investigate the genotoxic effect of marine sediments on aquatic organism, sediment samples were collected from 13 sites along the coast of Gwangyang Bay (Korea). Concentrations of polycyclic aromatic hydrocarbons (PAHs) in sediments were determined and the relationship between exposure of flounder blood cells to sediment extracts and DNA single-strand breakage in the blood cells was examined using the comet assay. Levels of DNA damage were proportionally increased by exposure concentration and the highest sediment-associated DNA damage was observed at the station showing the highest PAHs contamination. DNA damage in blood cells exposed to five types of PAHs (benzo[a]pyrene, fluoranthene, anthracene, pyrene and phenanthrene) and in flounder (Paralichthys olivaceus) exposed to benzo[a]pyrene (BaP) for 0, 2 and 4 days were assessed by measuring comet tail length. The tail lengths of five PAHs-exposed groups at 50 and 100 ppb were significantly different from the non-exposed group, and the genotoxic effect of BaP correlated with both concentration and duration of exposure. Throughout the study, significant differences in DNA breakage were recorded between cells exposed to sediment extracts or PAHs and non-exposed control. This study demonstrated the comet assay as a successful tool in monitoring contamination of marine sediments and assessing genotoxicity of PAHs in marine organisms, either in vitro or in vivo.     

Effects of benzo(a)pyrene exposure on the antioxidant enzyme activity of scallop <Emphasis Type="Italic">Chlamys farreri</Emphasis>

Scallop Chlamys farreri was exposed to different concentrations of benzo(a)pyrene (BaP) (0.5 μg/L, 1.0 μg/L, 10.0 μg/L and 50.0 μg/L) for 30 days in seawater. The 7-ethoxyresorufin O-deethylase (EROD) activity was significantly induced, and increased with the increasing BaP concentration. The glutathione-S-transferase (GST), superoxide dismutase (SOD), catalase (CAT), Glutathione peroxidase (GPx) activities increased in short time at low concentration of BaP, and was significantly depressed at high concentrations. Scallop gill was more sensitive to BaP than the digestive gland, and the digestive gland was the main tissue to deal with oxyradicals. The contents of malondialdehyde (MDA) increased with the exposure time and there was a positive correlation (concentration-effect) between the MDA content and the concentration of BaP. The biomarkers determined in this experiment had important roles in detoxification, and showed great potential as biomarkers for oxidative stress. Controlled laboratory experiments designed to simulate field exposure scenarios are particularly useful in ascertaining biomarkers suitable for use with complex contaminant mixtures in the marine environment. Supported by the Technology Development Program of Shandong (No. 2008GG1005010) and the Program of Introducing Talents of Discipline of Universities (111 Project, No. B08049)     

Immunotoxicity Effect of Benzo[α]Pyrene on Scallop Chlamys f arreri

The toxic effects of benzo[α]pyrene （B[α]P） at different concentrations （0.1, 0.5, 1, 2.5 and 7.5 μgL^-1） on scallop （Chlamys farreri） immune system were studied. The results showed that B[α]P had significant toxic effects on the haemocyte counts, neutral red uptake, phagocytosis, bacteriolytic and antibacterial activity （P〈0.05）, while the seawater control and acetone control had no significant differences. The haemocyte counts, neutral red uptake, phagocytosis and bacteriolytic activity in all B[α]P treatment groups as well as antibacterial activity in groups of 0.5, 1, 2.5 and 7.5 μgL^-1·B[α]P decreased significantly （P〈0.05）. Some of these indices tended to be stable on the sixth day and others on the ninth day, and the indices showed clear time- and concentration-response to B[α]E Bactenolytic activity in 0.1 μgL^-1 B[α]P treatment group and antibacterial activity in 0.1 ggLl and 0.5 μgL^-1 B[α]P treatment groups increased at the beginning of exposure and reached their peaks on day 1 and day 6, respectively. Following that, both activities decreased gradually and became stable after day 9. When all the indices reached stability, they were significantly lower than those in control group （P〈0.05）, except for antibacterial activity in 0.1 μgLl B[α]P treatment group （P〉0.05）. Thus, B[α]P has evident toxic effects on scallop immune system, which supports the view that a relationship exists between pollution and lmmunomodulation in aquatic organisms.     

通过探针分子芘研究超临界CO_2流体密度不均一性

近年来超临界CO2在环境地球科学领域应用广泛,在这些研究应用中,CO2流体在超临界状态下的溶剂化特性起到了十分重要的作用。在超临界高密度压缩区域里,体系温度和压力的稍许变化都会导致流体密度的突变,因此通过有效的探针分子研究超临界CO2流体的异常溶剂化行为具有重要的理论和应用价值。文中从新的角度运用荧光探针分子芘在温度308.15K和不同压力下研究超临界CO2性质,与以往采用的参照线方法有所不同,文中所提出的参照点模型手段引入序参量方法和新定义的溶剂化作用参量,测定近临界区超临界CO2流体局域密度增强的变化。文中同时讨论了3段密度区域模型(three-density regionmodel)、局域密度不均一性以及探针芘在超临界CO2中的分子间相互作用。将荧光探针分子研究的流体局域密度增强与热力学测试的流体等温压缩系数进行综合对比,有助于更好地从微观和宏观两方面理解超临界CO2的特性。     

A laboratory and field comparison of sediment polycyclic aromatic hydrocarbon bioaccumulation by the cosmopolitan estuarine polychaete Streblospio benedicti (Webster)

Polycyclic aromatic hydrocarbon (PAH) bioaccumulation by the polychaete worm Streblospio benedicti (Webster) was measured under exposure to PAH-contaminated sediments in the field and for 28 d in the laboratory. Streblospio benedicti collected from field sediments contaminated at 2.94, 1.07, and l.52 μg g⁻¹ fluoranthene (FLU), benz[a]anthracene (BAA), and benzo[a]pyrene (BAP), bioaccumulated those PAHs at 1.53, 0.215, and 0.332 μg g⁻¹, while worms isolated from less contaminated field sediments (0.399, 0.228, 0.288 μg g⁻¹ FLU, BAA, and BAP) had FLU, BAA, and BAP body burdens of 0.543, 0.236, and 0.083 μg g⁻¹. Worms incubated for 28 d in PAH-spiked sediments (1.52, 0.991, 0.504 μg g⁻¹ FLU, BAA, and BAP) bioaccumulated those PAHs at 0.382, 0.966, and 0.602 μg g⁻¹, respectively. Data normalization to organism lipid and sediment organic carbon (biota-sediment accumulation factors [BSAFs] strongly suggest that Streblospio PAH bioaccumulation was directly related to percent sediment organic carbon, but BSAFs were substantially lower than predicted by equilibrium partitioning theory. BSAFs decreased with increasing PAH log K_ow, in worms collected from field sediments, but in spiked sediments BSAFs increased with increasing PAH hydrophobicity. This disparity may have been caused by insufficient spiked-sediment equilibration time (1.5h) in the case of the laboratory test sediments.     

一株芘降解菌Bacilluscereus Py5的分离鉴定

为了研究蜡状芽孢杆菌的筛选、鉴定及对四环多环芳烃芘的降解性能。通过富集驯化培养,从红树林污泥中分离到一株以芘作为唯一碳源与能源的高效菌株PY5,经过形态观察、生理生化与16S rDNA鉴定, PY5属于蜡状芽孢杆菌(Bacillus cereus),同时对该菌株降解芘性能进行了系统研究。结果表明,B.cereus对50mg/L芘的21d降解率为65.8%,投加Tween-80、葡萄糖、水杨酸、Fe3+、Mn2+等基质可以不同程度强化降解芘的能力,其中投加葡萄糖+Fe3++Mn2+的混合液对B. cereus降解芘的强化效果最好, 21 d的芘降解率可达到81.4%,相对于不加共代谢底物时提升15.6%,表明外加C源与酶活诱导因子对高分子质量多环芳烃污染降解具有一定的促进作用。