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101.
R. J. Scheffer D. M. Elgersma Letty A. De Weger G. A. Strobel 《European journal of plant pathology / European Foundation for Plant Pathology》1989,95(5):281-292
To understand the mechanisms involved in biological control of Dutch elm disease byPseudomonas, data were needed on the distribution of the introduced bacteria within elm and on the development of the bacterial population over a period of time.As traditional biochemical identification techniques are not suitable for distinguishment between individualPseudomonas isolates, three alternative approaches were compared.
相似文献
1) | Chemotaxonomy, using lipopolysaccharide pattern, cell envelope protein pattern or DNA restriction fragment pattern. These techniques were reliable, but tedious. |
2) | Labeling bacteria with a transposon (Tn903) or a plasmid construct (pMON5003) with a metabolic marker (Lac ZY, coding for -galactosidase and lactose permease) allowed for a reliable identification of reisolates. However, populations of transposon-labeled bacteria in elms declined much faster than populations of the unlabeled wild type. The plasmid carrying the metabolic marker disappeared from the bacterial populations over time. Apparently both the transposon and the plasmid were a disadvantage to the bacteria compared with the wild type parent strains. |
3) | Immunoagglutination of representative reisolates with an antiserum against theP. fluorescens isolate in use proved to be specific and fast. For routine purposes the immunoagglutination test therefore was the best method of the various ones employed. |
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106.
猪链球菌2型srtA基因缺失菌株的构建及生物学特性 总被引:1,自引:0,他引:1
扩增了srtA基因的上、下游同源臂P1和P2及其全长序列,利用温度敏感型"自杀性"质粒pSET4s构建了重组质粒pSET4s-P1-P2,并将该质粒电转化入野生菌株SS2(SC21)中,通过抗生素和温度双重筛选,得到srtA基因缺失菌株,命名SC211.同时,将srtA基因定向插入穿梭质粒pAT18,构建穿梭质粒pAT18-srtA,并将该质粒电转入srtA基因缺失菌株SC211中,通过抗生素筛选,得到质粒介导的srtA基因互补菌株SC212.通过PCR、South-ern blotting等对缺失突变菌株和互补菌株进行了鉴定.对基因缺失突变菌株和回复菌株传代培养遗传稳定性试验结果显示,缺失突变菌株和互补菌株能够稳定遗传.比较了基因缺失突变菌株、互补菌株及野生菌株的生长特性、溶血活性、细胞粘附特性,结果表明,3个菌株的生长速度、溶血活性没有明显差异.基因缺失后SS2对Hep2细胞的粘附能力明显下降,只有野毒菌株的49%,互补菌株粘附能力几乎达到野毒菌株的水平,是野毒菌株的89%.CD1小鼠毒力试验结果显示,srtA基因缺失株SC211的LD_(50)(4.93×10~7)约为野毒菌株SC21的LD_(50)(8.21×10~6)的6倍,质粒介导的互补菌株SC212的LD_(50)(1.43×10~7)是野生菌株SC21的1.7倍,接近野毒菌株的水平,说明srtA基因缺失后SS2毒力显著下降. 相似文献
107.
毛状根是产生植物次生代谢产物的重要生物反应器。本文简述了发根农杆菌Ri质粒诱导植物产生毛状根的基本原理与方法及影响因子,对毛状根培养次生代谢物在药用植物上的应用作了概述,并提出其产业化前景、存在的问题。 相似文献
108.
对江西省樟树市某鸭养殖场送检的病死鸭进行病理剖检,通过细菌分离、生化鉴定得到1株致病性大肠杆菌。药敏试验结果表明,该菌株对头孢拉定、头孢唑啉、头孢曲松和阿莫西林等β-内酰胺类抗生素产生了严重的耐药。通过质粒提取和接合转移试验对分离菌株进行耐药性分析;提取得到一10 kb左右的质粒;质粒接合转移试验表明,成功将该质粒转化入感受态E.coli JM109,并能使E.coli JM109获得对β-内酰胺类抗生素耐药且与分离菌株的耐药谱一致。推测该菌株产β-内酰胺酶的基因存在于质粒,并且该耐药基因能随质粒的转移转化入敏感菌E.coli JM109。 相似文献
109.
为了构建猪囊尾蚴(Cysticercuscellulosae)热休克蛋白的真核表达载体,试验利用PCR技术扩增HSP35.6的基因,将其与增强型绿色荧光蛋白的基因先后连接到pVAXI真核表达载体上,得到pVAXI—HSP35.6-EGFP的重组质粒,经酶切及测序鉴定正确。采用脂质体介导的DNA转染法,将阳性重组质粒转染Vero细胞。转染48h后荧光显微镜下观察到明亮的绿色荧光,说明融合基因可在Vero细胞中高效表达。本研究为进一步研究该蛋白生物学功能奠定了基础。 相似文献
110.
Prasannan Geetha Preena Arathi Dharmaratnam Vattiringal Jayadradhan Rejish Kumar Thangaraj Raja Swaminathan 《Aquaculture Research》2021,52(1):237-248
For the sustainable farming of tilapia, proper maintenance of their health and adequate treatment for infections at appropriate time are inevitable. The indiscriminate use of antibiotics in aquaculture, as a part of treatment and as growth promoters, accelerates antimicrobial resistance (AMR) among the fish pathogens. In the present study, we have isolated diverse aeromonads from Nile tilapia and studied their antibiogram and plasmid profiling. Aeromonas hydrophila, Aeromonas veronii, Aeromonas sobria, Aeromonas dhakensis, Aeromonas caviae, Aeromonas jandaei and Aeromonas aquatica were isolated from infected tilapia (n = 150), and their Shannon wiener diversity index was calculated as 1.926. A. veronii was found to be the most multiple antibiotic‐resistant pathogen with the MAR index of 0.46, and A. aquatica was noticed as the least resistant isolate. The minimum inhibitory concentration of resistant antibiotics was shown as >256 mcg/ml for most of the isolates. The virulent genes such as aerolysin and hemolysin were identified in all the isolates except A. aquatica. The detection of class 1 integrons, plasmid profiling and plasmid curing studies confirmed that AMR exhibited by most of the Aeromonas species is of plasmid mediated. This challenges the risk of wide spread of AMR among the pathogens and subsequent treatment of the infection. 相似文献