大豆根边缘细胞对土荆芥组培根分泌物的响应

运用组织培养技术和悬空气培养法,研究了大豆根边缘细胞对土荆芥组培根分泌物的响应。结果表明：在土荆芥组培根分泌物作用下,随处理浓度的升高和处理时间的延长,边缘细胞数量和存活率持续下降。游离的根边缘细胞周围聚集了一些颗粒状物质,根边缘细胞可能螯合土荆芥根系分泌物。土荆芥根系分泌物能促进根冠果胶甲基酯酶活性上调,但是随着处理浓度增大和处理时间延长,这种促进效应降低。这些结果表明土荆芥组培根分泌物对大豆根边缘细胞具有一定的胁迫效应,根边缘细胞通过加速死亡并分泌一些活性物质螯合土荆芥根系分泌物,可在一定范围内缓解根系分泌物的毒害作用。     

土荆芥挥发油对豌豆根边缘细胞的诱导和胁迫作用

为探讨化感胁迫对根边缘细胞的诱导效应,实验采用悬空气培养法培养豌豆(Pisum sativum L.)露白种子,在保留根边缘细胞和去除根边缘细胞状态下,选取相对根长、根边缘细胞数量及死亡率、果胶甲基酯酶（PME）等指标研究了豌豆根边缘细胞对不同剂量土荆芥挥发油化感作用的响应。结果表明：1）与对照相比,随着挥发油处理剂量增加,根的伸长被显著抑制（P<0.05）。2）每个处理时间内,随着土荆芥挥发油剂量增加,根边缘细胞数量整体表现出先增加后减少的趋势,在低剂量2μL处理中达极大值。3）土荆芥挥发油诱导豌豆根边缘细胞死亡,随着处理时间的延长和处理剂量的增加,这种毒害效应程度加剧,除去边缘细胞实验组中10μL挥发油处理24 h时,根边缘细胞死亡率达到100%。在较低剂量挥发油作用下,保留根边缘细胞组的根边缘细胞死亡率高于去除根边缘细胞组,而在高剂量挥发油处理情况则相反。4）在同一处理时间,随挥发油剂量增加,各处理组PME活性持续升高,去处边缘细胞组处理24 h后不同剂量处理皆显著高于对照,而根边缘细胞数量总体表现先增加后减少。综合以上结果,保留根边缘细胞的根尖根边缘细胞的数量减少量较少,说明根边缘细胞能缓解土荆芥挥发油的化感胁迫;去除根边缘细胞组的PME活性升高较多,表明土荆芥化感胁迫诱导了根边缘细胞的产生。     

Synergic degradation of diesel by Scirpus triqueter and its endophytic bacteria

The endophytic bacterium isolated from Scirpus triqueter was proved to be an oil-degraded bacterium. A pot experiment was conducted to investigate the removal ratio of diesel under the combined effect of oil-degraded microorganism (Pseudomonas sp. J4AJ) and S. triqueter. The effect of diesel on plant growth parameters, soil enzymes and microbial community was assessed after 60 days. The results showed that the soils which were planted with S. triqueter and inoculated with J4AJ displayed the highest removal ratio (54.51?±?0.15 %) after 60-day experiment. However, the removal ratio of J4AJ-treated soils was 38.97?±?0.55 %. Diesel was toxic to S. triqueter, as evidenced by growth inhibition during the experimental period. However, the plant height and stem biomass in the soils inoculated with J4AJ significantly increased. The combined effect of S. triqueter and J4AJ improved the enzyme activities of the catalase and dehydrogenase in the contaminated soil. The diversity index in soils under the effect of S. triqueter combined with J4AJ was lower than that of the other soil samples. The principal analysis of phospholipid fatty acid signatures revealed that the combined effect of S. triqueter and J4AJ increased the differences of soil microbial community structure with the other treatments.     

分段进水多级生物膜反应器脱氮效能影响因素研究

采用分段进水多级生物膜反应器处理高氮低碳小城镇污水,考察负荷、溶解氧和温度对反应器脱氮效能的影响。实验结果表明:负荷、溶解氧和温度对反应器脱氮效能有显著影响。在水温为20～25℃,DO为5 mg/L,负荷为1 kgCOD/(m3.d),挂膜密度为30%,第1、3、6级分段进水,流量分配比为2∶2∶1的条件下,在反应器中可成功构建出高效同时硝化反硝化系统,出水COD、NH4+-N和TN浓度分别为33 mg/L、2.6 mg/L和29.4 mg/L,去除率分别为90.1%、96.0%和63.9%。当水温≤15℃时,硝化速率受温度的影响显著。     

Enhanced visual detection of pesticides using gold nanoparticles

The presence of parts per billion (ppb) levels of chlorpyrifos (O,O-Diethyl-O-(3,5,6-trichloro-2-pyridyl) phosphorothioate) and malathion (S-1,2-bis(ethoxycarbonyl) ethyl O,O-dimethyl phosphorodithioate), two common pesticides found in the surface waters of developing countries, have been visually detected using gold nanoparticles. Visual detection of the presence of pesticide is possible when the color change occurring by the adsorption of pesticides on gold nanoparticles is enhanced by sodium sulfate. The method presented here is simple and there is no need of sample preparation or preconcentration. The response occurs within seconds and the color change is very clear. The detection is possible if chlorpyrifos and malathion are present up to a concentration of 20 and 100 ppb, respectively. The method shows great potential for on-site pesticide monitoring. The method is also applicable as a qualitative technique for the performance evaluation of various household water filters, which claim pesticide removal.     

Short-term effects of diesel fuel on rhizosphere microbial community structure of native plants in Yangtze estuarine wetland

Purpose

In this work, short-term effects of diesel fuel on Huangpu?CYangtze estuarine wetland soil microbial community structure were studied under simulated conditions through phospholipid fatty acids (PLFAs) analysis. Four native plant species, bulrush (Scirpus tripueter), galingale (Cyperus rotundus), wildrice (Zizania latifolia), and reed (Phragmites australis) were tested in the experiments.

Method

In the pot experiment, 20?g rhizosphere soils were mixed with 20?g diesel-blended soils. The concentration of total petroleum hydrocarbon was 16,000?mg/kg. All pots were incubated for 14?days in dark at 28°C and watered with 12?mL sterile distilled water to keep a liquid level. Microbial activity of the samples was assessed by hydrolysis of fluorescein diacetate. Measurements of soil PLFAs and analysis on gas chromatography were performed.

Results

The microbial activity in the samples of reed was highest after the exposure. In all samples, the common PLFA was straight-chain saturated fatty acid (SFA) and monounsaturated fatty acid (MUFA). After the exposure the relative abundance of MUFA and polyunsaturated fatty acid decreased by 20%, and the relative abundance of straight-chain SFA increased by 20%. The results of diversity and PCA indicated that the effect of diesel pollutant on the microbial community was far stronger than the root effect and the reed roots enhanced the tolerance of soil microorganisms to diesel significantly.

Conclusions

All results showed that the soil microbial community structure differed significantly with the exposure to diesel. In reed rhizosphere, the soil microorganisms exhibited a strong resistance to diesel fuel. It confirmed that the root of reed improved the biodegradation ability of soil microorganisms for diesel pollutants and they could be reasonably matched to cure and restore the ecological environment of oil-contaminated wetlands.     

Change in genotoxicity of wastewater during chlorine dioxide and chlorine disinfections and the influence of ammonia nitrogen

The effects of chlorine dioxide and chlorine disinfections on the genotoxicity of different biologically treated sewage wastewater samples were studied by umu-test. The experiment results showed that when chlorine dioxide dosage was increased from 0 to 30 mg/L, the genotoxicity of wastewater first decreased rapidly and then tended to be stable, while when the chlorine dosage was increased from 0 to 30 mg/L, the genotoxicity of wastewater changed diversely for different samples. It was then found that ammonia nitrogen did not affect the change of genotoxicity during chlorine dioxide disinfection of wastewater, while it greatly affected the change of genotoxicity during chlorine disinfection of wastewater. When the concentration of ammonia nitrogen was low (< 10–20 mg/L), the genotoxicity of wastewater decreased after chlorine disinfection, and when the concentration of ammonia nitrogen was high (> 10–20 mg/L), the genotoxicity of wastewater increased after chlorine disinfection.     

Abundance and diversity of Sphingomonas in Shenfu petroleum-wastewater irrigation zone, China

Introduction  

Members of the genus Sphingomonas have raised increasing attention due to their ability for polycyclic aromatic hydrocarbon (PAH) degradation and their ubiquity in the environment. However, few studies have revealed the ecological information on the abundance and diversity of Sphingomonas in the environment.     

基于功能基因表达的高氯酸盐与硝酸盐氮修复

为更好地研究环境中高氯酸盐离子(ClO-4)与硝酸盐氮(NO-3-N)混合污染的共同降解。选用pcrA、cld基因表征参与高氯酸盐降解的细菌,NirS基因表征反硝化细菌,16S rRNA基因表征整个细菌群落的活性。通过对高浓度硝酸盐氮与高氯酸盐混合污染降解体系内不同时间点不同种基因的表达分析,实时定量的反应复杂环境中混合污染物生物降解机理。结果表明,在外源添加足够的醋酸盐作为电子供体条件下,NO-3-N与ClO-4质量浓度比为5∶1时,硝酸盐氮的存在不会完全抑制ClO-4的降解,当NO-3-N降解完全时,可以加快ClO-4的降解过程。在有硝酸盐氮存在的混合降解体系内,pcrA和cld基因与ClO-4的浓度变化之间的相关性不是很高,证明该功能基因对复杂环境中特定生物群落的表征有一定局限性。     

青藏高原东北部热融滑塌区土壤碳氮磷含量

全球变暖加剧多年冻土退化,导致地表沉降等热喀斯特现象,进而会改变土壤理化性质,但热融滑塌对土壤理化性质的影响还不清楚。该研究选择青藏高原东北部高寒草甸区3条热融滑塌沟的3种微地貌(对照区、滑塌区、沉降区)样地,采集0～15 cm、15～30 cm的土壤,测定其有机碳(SOC)、全氮(TN)、全磷(TP)、溶解有机碳(DOC)、总溶解氮(TDN)、磷酸盐(P-PO_4)、pH、含水率等理化性质,分析热融滑塌对土壤理化性质的影响。结果发现:(1)热融滑塌导致表层土壤C、N、P含量大幅降低,其中0～15 cm层土壤SOC、TN、TP含量在0～15 cm层分别减少42%、38%、22%,土壤可溶性DOC、TDN、P-PO4分别减少60%、24%、44%;15～30 cm层土壤中,SOC、TN、TP含量分别减少16%、23%、21%,土壤可溶性DOC、TDN、P-PO4分别减少33%、30%、38%。(2)pH与土壤含水率与土壤C、N、P含量密切相关,滑塌后土壤pH升高、含水率降低,同时土壤C、N、P含量降低。结果表明热融滑塌会降低多年冻土区土壤C、N、P的含量。