杜氏藻与大肠杆菌跨界融合初探

以链霉蛋白酶制得了杜氏藻(嗜盐单胞绿藻)的原生质体。采用聚乙二醇(PEG)-钙离子法将它们与大肠杆菌(含氯霉素乙酰转移酶基因质粒)的球1,20,1状体进行融合。“融合子”酷似杜氏藻。它们对氯霉素抗性的显著提高寓示了大肠杆菌的质粒已转移到“融合子”细胞中;而且,“融合子”的蛋白质组分与杜氏藻和大肠杆菌相比已发生了较明显的变化。     

致病性鳗弧菌W-1外膜蛋白ompU基因克隆及在大肠杆菌中的表达

从致病性鳗弧菌W-1基因组DNA扩增并克隆了1 156bp的特异性片段,含有完整的外膜蛋白ompU基因阅读框,由993个核苷酸组成,编码330个氨基酸残基的蛋白质。与国外已发表的鳗弧菌外膜蛋白基因的序列同源性为100%,与创伤弧菌(Vibrio vulnificus)、霍乱弧菌(Vibrio cholerae)、费氏弧菌(Vibrio fischeri)和副溶血弧菌(Vibrio parahaemolyticus)的序列同源性分别为72%,69%,68%和64%。将该外膜蛋白基因克隆于pBV220表达质粒,在大肠杆菌中得到了表达,SDS-PAGE分析表明表达蛋白分子量约38kDa,Western blot分析发现表达蛋白能与鳗弧菌外膜蛋白抗体很好的反应。     

Impact of land use on the faecal microbial quality of hill‐country streams

Faecal contamination of rural streams is of increasing concern in New Zealand. This study assessed hill‐country streams in the Whatawhata district that were impacted by pastoral farming, indigenous forest, or Pinus radiata forest; by measuring Escherichia coli bacteria at 14 sampling sites fortnightly for 2 years. E. coli concentrations were highest in streams flowing through grazed pasture. In both years there was a noticeable seasonal pattern in all streams irrespective of land use, with highest bacterial concentrations in summer and autumn and lowest in winter and early spring. There was no obvious correlation between E. coli concentration and rainfall or stream flow. In those streams impacted by a change in land use from pastoral to pines during the study, E. coli concentration fell rapidly and remained at levels lower than those in streams impacted by either indigenous or 7‐year pine forests. As E. coli was detected in all but two samples, the water in these streams is not suitable for human consumption. The pastoral streams consistently failed to meet stock drinking‐water guidelines (median concentration not greater than 100 E. coli 100 ml^–1) and the forest streams failed to do so in summer. Twenty‐eight percent of pastoral samples, 25% of indigenous forest samples, 14% of 7‐year pine forest samples, and 5% in New Pines stream samples (after planting) had E. coli concentrations associated with a high level of risk for contact recreation (>500 E. coli 100 ml^‐1) and the high concentrations usually occurred in summer.     

间接酶联免疫吸附技术检测活的非 可培养状态的大肠杆菌O157：H7

大肠杆菌O157H7在低温贫营养的条件下可进 入活的非可培养状态（Viable but nonculturable state,VBNC），用常规的培养法无法将其检出。作者利用间接酶联免疫吸附技术（Indirect Enzyme-Linked Immunosorbent Assa y, ELISA）检测VBNC的大肠杆菌O157H7，发现此方法可以快速有效地将其检出，最小检测 浓度为10     

澳大利亚昆士兰州西北世纪锌铅银矿床的地球物理特征

世纪锌铅银矿床由CRA公司于1990年发现,并进行勘探.钻探圈定出锌(10.3%)、铅(1.5%)、银(35×10^-6)的矿石量达11600万t.矿床被发现以来,物探技术就应用于帮助确定矿化范围,不同岩性边界和构造的圈定,提供矿石储量的计算和采矿计划的资料以及该区下一步勘探工作帮助.使用的物探方法有重力、地面和航空磁法、地面和航空电磁、IP/电阻率法、钻孔物探测井及地震反射.最为有效的方法是IP/电阻率法.它可以帮助确定在深度至少为150m的石灰岩和年轻盖层下的矿化范围     

Escherichia coli strains harvested from springs in Kampala,Uganda: cell characterization and transport in saturated porous media

We hypothesized that the transport of Escherichia coli strains harvested from springs could be characterized by a similar set of cell characteristics and transport parameters. The hypothesis was tested by sampling springs throughout the Lubigi catchment in Kampala, Uganda. Chemo‐physical parameters in addition to total coliform concentrations were determined. Furthermore, E. coli strains were harvested, and cell properties determined. Column experiments in saturated quartz columns of 7 cm height were conducted to determine transport parameters of selected E. coli strains. Using a two‐site non‐equilibrium sorption model, transport was modelled by fitting breakthrough data in HYDRUS 1D. Results indicated faecal contamination of the springs with high concentrations of total coliforms, chloride and nitrate. Furthermore, the maximum relative E. coli concentrations (C/C₀)_max in the column experiments were high. Compared with our previous work on E. coli strains, collected from a pasture and from zoo animals, attachment was low. Modelling revealed that both equilibrium and kinetic sorption were not important under conditions employed in the experiments. These observations are explained by the way in which the strains were harvested: from termination points of flow lines (springs). Such strains may possess characteristics that might have influenced their transport in the subsurface leading to their low attachment efficiency and possibly contributing to the lack of influence of equilibrium and kinetic sorption characteristics. There was no significant correlation between cell properties and transport parameters. Furthermore, 58% of the tested strains were of the O21:H7 serotype, and all definable serotypes identified were associated with diseases. We speculate that this serotype may possess characteristics that allow preferential transport through the aquifers of the area. We demonstrated that bacteria harvested from termination points of flow lines compared with those obtained from pollution sources, which have not undergone transport yet, present a good option for the assessment of bacteria transport characteristics in aquifers. Copyright © 2013 John Wiley & Sons, Ltd.     

Faecal indicators and pathogens in selected New Zealand waterfowl

Freshly excreted droppings from Canada geese (n=80), black swans (n=80), ducks (n=80) and gulls (n=80) were collected from sites around New Zealand. The droppings were enumerated for Escherichia coli, enterococci and Salmonella spp., and for the presence/absence of Cryptosporidium spp. Overall prevalence of E. coli and enterococci in samples was 95% and 94%, respectively. Cryptosporidium spp. was detected in 2% of the samples, whereas no Salmonella spp. were detected in the survey. Preliminary estimates of daily microbial outputs suggest that ducks will produce the highest loadings of E. coli and enterococci per bird, whereas Canada geese will produce the highest loadings of Campylobacter spp. per bird. This study provides the first set of indicator and pathogen counts for one of the largest sources of diffuse faecal contamination of natural waters in New Zealand.     

Wachstum gentechnisch veränderter E. coli K—12-Zellen in Klärschlamm aus zwei Kläranlagen Growth of Genetically Modified E. coli K - 12 Cells in Sewage Sludge of Two Different Sewage Treatment Plants

The release of genetically engineered microorganisms may occur from research laboratories of production plants. The most important pathway of release is via the sewage system and the sewage treatment plants into surface waters. The growth of these organisms might represent a risk to the environment. Therefore the growth of a genetically engineered strain of E. coli K-12 was investigated. Aqueous supernatant from sewage sludge of two domestic sewage plants was used as medium. This medium was treated with sterile filtration and amended with nutrients. The test strain E. coli K-12 W3110i^qM15Nal^r(pBR322) did not show permanent growth under the conditions employed. The result is interpreted by the presence of bacteriophages and the poor nutritional conditions in the medium.     

演艺海豚混合感染大肠埃希氏菌和变形杆菌的检验分析

解剖了一条出现腹泻等症状、经治疗无效死亡的海豚 ,发现肺、肝、脾、胃等均有病变 ,从病变组织器官中分离到 7株细菌 ,通过菌株的形态、染色特征、生化特性、血清学鉴定 ,发现其中 5株菌株为大肠艾希氏菌 O8血清型 ,另 2株分别为普通变形杆菌和奇异变形杆菌。动物试验表明 ,大肠埃希氏菌和变形杆菌是海豚发病的致病菌。 7个菌株均对菌必治和先锋噻肟高敏 ,对氯霉素、链霉素、痢特灵等中敏 ,对青霉素 G、氨苄青霉素等耐药