16S rDNA克隆文库解析AO-MBR系统中细菌种群多样性

采用分子生物学手段16S rDNA克隆文库方法对缺氧/好氧膜生物反应器(AO-MBR)的好氧池与缺氧池中细菌进行了多样性研究.实验结果表明,好氧池污泥样品的克隆文库包括9个类群,其中变形菌(Proteobacteria)和拟杆菌(Bacteroidetes)在文库中所占比例最大,分别为37.04％和14.81％;其次是酸杆菌(Acidobacteria)、未培养菌(uncultured bacterium)、绿菌(Chlorobi)和未培养的绿弯菌(uncultured Chloroflexi bacterium)、浮霉状菌(Planctomycetes),分别为11.11％、11.11％、7.41％、7.41％和5.56％;硝化螺旋菌(Nitrospirae)和裸藻门(Euglenozoa)所占比例相对较小,均为1.85％.缺氧池样品克隆文库包括10个类群,其中变形菌(Proteobacteria)、拟杆菌(Bacteroidetes)和未培养菌(uncultured bacterium)在文库中所占比例最大,分别为27.91％、13.95％和12.79％;其次是浮霉状菌(Planctomycetes)、酸杆菌(Acidobacteria)和绿弯菌(Chloroflexi),在文库中所占比例分别为9.3％、9.3％和9.3％;硝化螺旋菌(Nitrospirae)、裸藻门(Euglenozoa)、芽单胞菌(Gemmatimonadetes)和放线菌(Actinobacteria)所占比例相对较少,分别为6.98％、8.14％、1.16％和1.16％.两池细菌的主要类群相似,但菌属及比例有所差异,变形菌是系统中的主要脱氮菌属.     

MoS_2/Bi_2S_3异质结光催化剂的制备及其光催化性能

以五水硝酸铋为铋源、钼酸钠为钼源、硫脲为硫源,采用简单的一步水热法合成了MoS_2/Bi_2S_3异质结光催化剂,采用XRD,SEM,TEM,BET,UV-Vis DRS技术对其进行了表征。表征结果显示,MoS_2纳米片在Bi_2S_3微棒表面生长,增加了比表面积和活性位点,并形成异质结构,促进了光生载流子的迁移,抑制了电子-空穴对的再复合。实验结果表明:钼酸钠与五水硝酸铋的质量比为1∶2时制备的复合光催化剂性能最好,反应180min时对亚甲基蓝的去除率可达96.4%,明显高于MoS_2和Bi_2S_3,且具有较高的稳定性;该催化剂对罗丹明B、甲基橙和4-硝基苯酚的去除率分别为97.1%、93.1%和90.5%,表明其对污染物具有普适性。     

浮游动物DNA宏条形码标志基因比较研究

DNA宏条形码技术作为一种新型生物监测方法,在未来生态环境监测中有巨大的应用潜力。目前,浮游动物DNA宏条形码监测仍在发展阶段,需要首先对其(采样方法、引物选择和数据分析等)进行标准化和调整,然后才能用于常规流域生态监测。其中,如何选择合适的PCR扩增引物是DNA宏条形码生物监测标准化的关键问题之一。本研究比较了COI、18SV9和16S通用引物在浮游动物DNA宏条形码监测中的差异,为初步建立规范化的浮游动物DNA宏条形码监测方法提供技术支撑。结果表明,16S引物对浮游动物具有更好的特异性,其产生的操作分类单元(operational taxonomic unit, OTU)有88.1%属于浮游动物。虽然18SV9引物具有更高的物种覆盖度,不仅能扩增出浮游动物,还能扩增出大量藻类和真菌,但其物种识别敏感性较差,不适合浮游动物物种水平多样性监测。COI引物的浮游动物物种特异性、物种覆盖度和物种识别敏感性都适中,检出的浮游动物物种数量高于18SV9引物和16S引物,更加适合浮游动物DNA宏条形码监测。     

基于3S技术对太湖底质及水质总磷的研究

应用3S技术研究了太湖底质与水质总磷(TP)的分布情况,并结合水华频次分析了其相关性。结果表明:2016—2018年,太湖底质TP年均值在433~537 mg/kg波动,水质TP年均值从0.064 mg/L上升至0.087 mg/L。从空间分布来看,底质TP、水质TP和水华频次均呈现“西高东低”的规律,太湖西部区尤其是竺山湖区是需要开展治理的重点区域。3年间,太湖西部区水质TP上升,而底质TP与入湖河流TP下降,说明内源磷污染是太湖西部区水质TP升高的主要原因,须加强科学清淤。     

气相色谱法测定水质中的内吸磷

优化了气相色谱法测定水质中的内吸磷,当取样量为100 m L时,内吸磷-O方法检出限为0. 30μg/L,测定下限为1. 20μg/L;内吸磷-S方法检出限为0. 80μg/L,测定下限为3. 20μg/L。内吸磷-O和内吸磷-S标准曲线线性良好,相关系数分别为0. 999 2和0. 999 8。不同水质中内吸磷-O的加标回收率为90. 3%～104%,相对标准偏差为3. 6%～9. 2%;内吸磷-S的加标回收率为92. 1%～94. 9%,相对标准偏差为4. 6%～8. 7%。该方法灵敏度高,能有效分离内吸磷-O和内吸磷-S,同时能将内吸磷-O、内吸磷-S与其他有机磷农药类干扰物分离。     

Dry and heat stress affects H2S production of Salmonella on selective plating media

The pH of Salmonella pre-enrichment media can become acidic (pH 4.0–5.0) when feeds/ingredients are incubated for 24?h. Salmonella in feed that have been stressed by heat and desiccation exhibit different pH tolerances than non-stressed cultures. Acidic conditions can result in cell injury/death and affect biochemical pathways. In this study, eight serotypes of Salmonella were grown in sterile meat and bone meal that was subjected to desiccation and heat stress. Cultures of non-stressed and stressed isolates were subsequently exposed to acidic pH from 4.0 to 7.0 in 0.5?pH increments (3 replicates/pH increment) in citrate buffer. At 6 and 24?h, serial dilutions were plated in duplicate on XLT-4 (xylose lysine tergitol-4) agar. Four serotypes showed an impaired ability to decarboxylate lysine on XLT-4. This inability to decarboxylate lysine was dependent on isolate, stress status, and incubation time. When the isolates’ ability to decarboxylate lysine was examined using biochemical tests, cultures were found to be able to decarboxylate lysine with the exception of S. Infantis. This suggests that XLT-4 contains a biochemical stressor(s) which affects the rate of decarboxylation by these Salmonella. These results suggest that acidic conditions may influence the detection and confirmation of Salmonella in feed.     

浅谈“5S”在环境监测业务管理中的应用研究

将“5S”管理概念应用到环境监测业务管理工作中.将“5S”针对企业管理的方法引入环境监测业务工作中,从工作环境、工作纪律、工作方法、工作安全方面进行一系列的应用.引入“5S”概念改进环境业务管理要求、提高环境监测工作效率、提升环境监测人员素质、加强环境监测的规范性和有效性,以一流的设备、技术、人才和管理,为用户提供高效优质的服务.“5S”管理理念应用于环境监测业务管理有助于环境监测业务工作的建设和提升.     

Pd/activated carbon sorbents for mid-temperature capture of mercury from coal-derived fuel gas

Higher concentrations of Hg can be emitted from coal pyrolysis or gasification than from coal combustion, especially elemental Hg. Highly efficient Hg removal technology from coal-derived fuel gas is thus of great importance. Based on the very excellent Hg removal ability of Pd and the high adsorption abilities of activated carbon（AC） for H2 S and Hg, a series of Pd/AC sorbents was prepared by using pore volume impregnation, and their performance in capturing Hg and H2 S from coal-derived fuel gas was investigated using a laboratory-scale fixed-bed reactor. The effects of loading amount, reaction temperature and reaction atmosphere on Hg removal from coal-derived fuel gas were studied. The sorbents were characterized by N2 adsorption, X-ray diffraction（XRD） and X-ray photoelectron spectroscopy（XPS）. The results indicated that the efficiency of Hg removal increased with the increasing of Pd loading amount, but the effective utilization rate of the active component Pd decreased significantly at the same time. High temperature had a negative influence on the Hg removal. The efficiency of Hg removal in the N2-H2S-H2-CO-Hg atmosphere（simulated coal gas） was higher than that in N2-H2S-Hg and N2-Hg atmospheres, which showed that H2 and CO, with their reducing capacity, could benefit promote the removal of Hg. The XPS results suggested that there were two different ways of capturing Hg over sorbents in N2-H2S-Hg and N2-Hg atmospheres.     

Reduction and characterization of bioaerosols in a wastewater treatment station via ventilation

Bioaerosols from wastewater treatment processes are a significant subgroup of atmospheric aerosols. In the present study,airborne microorganisms generated from a wastewater treatment station(WWTS) that uses an oxidation ditch process were diminished by ventilation.Conventional sampling and detection methods combined with cloning/sequencing techniques were applied to determine the groups,concentrations,size distributions,and species diversity of airborne microorganisms before and after ventilation. There were 3021 ± 537 CFU/m3 of airborne bacteria and 926 ± 132 CFU/m3 of airborne fungi present in the WWTS bioaerosol.Results showed that the ventilation reduced airborne microorganisms significantly compared to the air in the WWTS. Over 60% of airborne bacteria and airborne fungi could be reduced after4 hr of air exchange. The highest removal(92.1% for airborne bacteria and 89.1% for fungi) was achieved for 0.65–1.1 μm sized particles. The bioaerosol particles over 4.7 μm were also reduced effectively. Large particles tended to be lost by gravitational settling and small particles were generally carried away,which led to the relatively easy reduction of bioaerosol particles0.65–1.1 μm and over 4.7 μm in size. An obvious variation occurred in the structure of the bacterial communities when ventilation was applied to control the airborne microorganisms in enclosed spaces.     

Bacterial degradation of monocrotophos and phyto- and cyto-toxicological evaluation of metabolites

The bacterium Serratia marsescens strain JAS16 was isolated from agricultural soil which had prior exposure to monocrotophos for three years. The strain JAS16 tolerated up to 1200 mg L^–1 monocrotophos and degraded the insecticide (1000 mg L^–1) at a degradation rate constant of 136 d^?1 (DT₅₀ = 3.7 d). In soil, the degradation rate constant was 105 d^?1 (DT₅₀ = 4.8 d). A schematic pathway is being proposed from the degraded products derived from gas chromatography--mass spectrometry (GC-MS). The phytotoxicity of degradation products to Vigna radiata, Vigna unguiculata, and Macrotyloma uniflorum and the genotoxicity to Allium cepa roots were found to be low. A cost-effective powder-based formulation was achieved with the isolate. The isolate remained viable during the storage and also multiplied with a higher colony forming units (CFU) load g^–1 for over a period of seven weeks of storage.