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1.
研究嗜酸乳杆菌、禽大肠杆菌O78、大肠杆菌ATCC 25922、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肉鸡不同肠段粘液糖蛋白的粘附性能,探讨嗜酸乳杆菌对四种病原菌的粘附排斥作用.结果表明,在不同的肠道部位,嗜酸乳杆菌、鸡白痢沙门氏菌和鼠伤寒沙门氏菌与肠粘液糖蛋白的粘附能力不同,而禽大肠杆菌O78、大肠杆菌ATCC 25922在各肠段粘液上的粘附性能相近;在相同的肠道部位,所试菌与肠粘液糖蛋白的粘附能力有差异,其中嗜酸乳杆菌的粘附作用最强;嗜酸乳杆菌对所试病原菌均有不同程度的粘附排斥作用,其中对鸡白痢沙门氏菌的粘附排斥较强,而对大肠杆菌ATCC25922的则较弱.  相似文献   

2.
《中国兽医学报》2017,(12):2260-2265
为了研究河北秦皇岛地区鸡致病性大肠杆菌(Escherichia coli,E.coli)地方流行株的优势血清型、毒力基因和致病性,本研究采用常规鉴定方法和16SrRNA PCR方法,从采集自河北秦皇岛地区不同养鸡场的83份病鸡组织中分离鉴定出56株E.coli。人工感染1日龄雏鸡试验表明,46株分离株为致病性E.coli。采用玻片凝集试验、PCR方法分别测定致病性E.coli分离株的血清型分布和16种毒力基因携带情况。结果显示,定型的42株致病性E.coli分离株包括11种血清型,以O7 8、O89、O142及O1为优势血清型;46株致病性E.coli分离株中以irp2、fuyA、ompT、Iss a、iutA、iroN和hlyF毒力基因检出率较高,在89.1%~100.0%,其他毒力基因检出率为22.0%~72.0%。选择优势血清型代表株QH1(O78)、QH1(O89)、QH1(O142)和QH1(O1)人工感染1日龄雏鸡,计算半数致死量(LD50),确定其致病性。结果表明,QH1(O78)株致病性最强,对1日龄雏鸡的LD50为3.16×106 CFU/mL;对14,49日龄雏鸡的LD50分别为1.07×107,5×108 CFU/mL。本研究为河北秦皇岛地区鸡致病性E.coli地方流行株防控提供试验依据。  相似文献   

3.
为了探究天然发酵酸马奶中发酵乳杆菌对致病性大肠杆菌O8(E.coli O8)的抑菌机理,本试验从酸马奶中分离筛选出抑菌效果最佳的菌株,对其进行16S rDNA序列鉴定,经NCBI网站BLAST对比鉴定菌种;对菌株进行培养发酵,制备无细胞发酵上清液(CFS);通过排酸、排过氧化氢(H2O2)、不同蛋白酶处理等方法初步确定CFS中的抑菌活性物质性质及其含量;采用牛津杯法和二倍稀释法确定CFS对致病性E.coli O824h生长曲线的最佳抑菌浓度;试剂盒法测定CFS对致病性E.coli O8的细胞膜和细胞壁通透性的影响。结果显示,从酸马奶中分离出22株对致病性E.coli O8有抑制作用的菌株,对抑菌作用最好的菌株进行16S rDNA序列鉴定及系统进化树分析后确定其为发酵乳杆菌属;CFS中主要的抑菌物质为蛋白,含量为399.5μg/mL;最低抑菌浓度(MIC)和最低杀菌浓度(MBC)分别为25.0和49.9μg/mL;CFS能使致病性E.coli O8的碱性磷酸酶(AKP)含量在1h内快速升高,之后呈缓慢增长趋势,且使致病菌培养液中的蛋白含量明显升高。综上所述,发酵乳杆菌CFS的主要抑菌物质为蛋白,蛋白浓度越高抑菌能力越强;CFS通过破坏或改变致病性E.coli O8细胞膜和细胞壁的通透性,使其释放出AKP和胞内蛋白,从而在短时间内起到抑制致病性E.coli O8生长的作用。  相似文献   

4.
采用1日龄雏鸡对1株O1血清型鸡源大肠埃希菌(E.coli)的致病性进行测定,并扩增iss基因.结果表明,鸡E.coli O1对1日龄雏鸡具有较强的毒力.iss基因在致病性鸡E.coli O1中的序列与已知禽大肠埃希菌iss基因序列同源性为100%,与人源大肠埃希菌iss基因核苷酸,序列同源性为90.9%,显示了此基因具有保守性.  相似文献   

5.
iss基因与鸡大肠杆菌毒力相关性的分析   总被引：1，自引：0，他引：1  
对20株鸡源大肠杆菌的致病性进行测定。并对不同致病性鸡大肠杆菌的iss基因进行了扩增。结果表明：鸡E．coli O1、O2、北京1、北京3、贵州1、新大、田大、E10、E11、E27对1日龄雏鸡具有较强的毒力;O78、E5、E21的致病性较弱;而E．coli E1、E4、E7、E8、E9、E14、E18接种雏鸡均无死亡。iss基因在致病性鸡E．coli O1、O2、O78、北京1、北京3、贵州1、新大、田大、E5、E21、E10、E11、E27中的扩增频率为92．31％;在毒力较强的致病性鸡Ecoli O1、O2、北京1、北京3、贵州1、新大、田大、E10、E11、E27中的扩增频率为100％;在无致病性(或低毒力)的鸡Ecoli E1、E4、E7、E8、E9、E14、E18中的扩增频率为14．29％。结果表明：iss基因在致病力强的菌株中的扩增频率明显高于其它菌株,iss基因的存在与鸡大肠杆菌的毒力问有一定的相关性。  相似文献   

6.
为研究Ⅰ型菌毛在F18ac大肠杆菌(F18ac E.coli)粘附过程中的作用,本研究利用λ-Red同源重组系统构建了F18ac E.coliⅠ型菌毛主亚基编码基因fim A缺失突变株(F18ac△fim A),以野生株为对照,通过体外易感细胞粘附试验和生物被膜(BF)形成定量试验,探索Ⅰ型菌毛在F18ac E.coli粘附宿主细胞过程中的作用。体外易感细胞粘附结果显示,经8%甘露糖封闭Ⅰ型菌毛受体或fim A基因缺失后,F18ac E.coli对易感仔猪上皮细胞IPEC-1的粘附能力均显著下降。BF结晶紫定量试验显示,F18ac△fim A菌株形成BF的能力显著下降,而F18ac△fim A/pfim A回补株的粘附能力以及生物被膜形成能力均得到了恢复。本研究表明Ⅰ型菌毛是F18ac E.coli重要的粘附素,介导了F18ac E.coli对仔猪易感细胞的粘附过程。本研究为进一步阐释F18ac E.coli致病机制中多毒力因子的作用提供了实验依据。  相似文献   

7.
为了探究不同蒙药对致病性大肠杆菌的抑菌效果,从而筛选出抑菌效果较好的药物进行试验。本研究选取了9味蒙药,通过牛津杯法、二倍稀释法以及小鼠致病性试验,测定不同蒙药对牛源致病性E.coli O78抑菌直径和最低抑菌浓度(MIC)。试验结果显示,除了柯子和多叶棘豆没有抑菌作用外,其余7味蒙药对致病性E.coli O78均有不同程度的抑制作用。其中黄连的体外抑菌效果最好,抑菌圈直径为22mm,表现为极敏,MIC为0.0039g/m L;姜黄的体外抑菌效果最差,抑菌直径为9mm,表现为低敏,MIC为0.5000g/m L。表明不同蒙药对致病性E.coli O78体外抗菌效果不同。黄连的抑菌效果最好,在较低药物浓度下对致病性E.coli O78有较强的抑制作用。本研究旨在筛选出对致病性E.coli O78抑菌效果较好的蒙药,从而为大肠杆菌病的防治提供科学的理论依据。  相似文献   

8.
从10日龄健康小鸡的小肠中成功分离筛选出有抑菌作用的嗜酸乳杆菌M16。颉颃病原菌试验表明,该菌株的代谢产物在体外具有抑制杀灭鸡大肠埃希氏菌O78、鸡白痢沙门氏菌O79和金黄色葡萄球菌C58000的作用,是微生态制剂可选用的优良菌株。  相似文献   

9.
中药对鸡致病性大肠埃希菌的体外抑菌试验   总被引：1，自引：0，他引：1  
为研究25种中药对秦皇岛地区鸡致病性大肠埃希菌(Escherichia coli)地方流行株QH1(O78)、QH2(O89)、QH4(O1)的体外抑菌效果,以E.coli标准株ATCC25922作为质控菌株。利用水提法制备中药药液,使终浓度为1g/mL;用平板琼脂打孔法和改良微量二倍稀释-平板法分别测定25种中药的抑菌圈直径和最小抑菌浓度(MIC)。结果表明,金银花、黄连、乌梅、五味子4种中药对鸡致病性E.coli地方株极度敏感,抑菌圈直径在20.3mm~22.7mm之间,其MIC在15.65mg/mL~31.25mg/mL之间;其他药物对鸡致病性E.coli地方株有不同程度的敏感性,为鸡致病性E.coli地方株中药防治提供理论基础。  相似文献   

10.
为了探究天然发酵酸马奶中发酵乳杆菌对致病性大肠杆菌O8（E.coli O8）的抑菌机理,本试验从酸马奶中分离筛选出抑菌效果最佳的菌株,对其进行16S rDNA序列鉴定,经NCBI网站BLAST对比鉴定菌种;对菌株进行培养发酵,制备无细胞发酵上清液（CFS）;通过排酸、排过氧化氢（H2O2）、不同蛋白酶处理等方法初步确定CFS中的抑菌活性物质性质及其含量;采用牛津杯法和二倍稀释法确定CFS对致病性E.coli O8 24 h生长曲线的最佳抑菌浓度;试剂盒法测定CFS对致病性E.coli O8的细胞膜和细胞壁通透性的影响。结果显示,从酸马奶中分离出22株对致病性E.coli O8有抑制作用的菌株,对抑菌作用最好的菌株进行16S rDNA序列鉴定及系统进化树分析后确定其为发酵乳杆菌属;CFS中主要的抑菌物质为蛋白,含量为399.5 μg/mL;最低抑菌浓度（MIC）和最低杀菌浓度（MBC）分别为25.0和49.9 μg/mL;CFS能使致病性E.coli O8的碱性磷酸酶（AKP）含量在1 h内快速升高,之后呈缓慢增长趋势,且使致病菌培养液中的蛋白含量明显升高。综上所述,发酵乳杆菌CFS的主要抑菌物质为蛋白,蛋白浓度越高抑菌能力越强;CFS通过破坏或改变致病性E.coli O8细胞膜和细胞壁的通透性,使其释放出AKP和胞内蛋白,从而在短时间内起到抑制致病性E.coli O8生长的作用。  相似文献   

11.
To test the interaction between various species of bacteria and Salmonella serovar typhimurium (S. typhimurium), the population of S. typhimurium was measured in the cecum of gnotobiotic chickens in the presence of Escherichia coli (E. coli) and one of the four intestinal bacteria; Lactobacillus acidophilus. Clostridium perfringens, Bifidobacterium thermophilum and Bacteroides vulgatus. Competitive exclusion of S. typhimurium by di-flora chicken was not demonstrated. But the population of S. typhimurium was temporarily suppressed in di-flora chickens with E. coli and L. acidophilus. In penta-flora chickens with E. coli and these four intestinal bacteria, the population of S. typhimurium was suppressed for only 2 days. In normalized chickens, the population of S. typhimurium was markedly suppressed.  相似文献   

12.
Two strains of E. coli O139:K12 (B):H1 were compared in vitro and in the intestinal environment. Both strains colonized the small intestines of experimentally inoculated pigs and exhibited in vivo a similar relationship to the microvillus border as enterotoxigenic E. coli (ETEC). Strain 107/86 grown on blood agar expressed numerous long flexible non-haemagglutinating fimbriae which were antigenically distinct from the known fimbriae of porcine ETEC. It adhered in vitro to porcine enterocyte brush border fragments. Strain 124/76 grown on blood agar was devoid of fimbriae and did not adhere to brush border fragments. However, fimbriae morphologically and antigenically indistinguishable from those of strain 107/86 were detected in the intestinal environment by direct immunofluorescence and by immuno electron microscopy.  相似文献   

13.
Glycated proteins are considered as one of the factors involved in the pathogenesis of diabetic complications, including nephropathy. These proteins are formed endogenously under conditions of hyperglycemia, as well as being provided with food containing sugars, which was subjected to high temperature. Examples are egg products. One of the proteins found in eggs in a relatively high concentration is chicken cystatin (ovocystatin). It is now believed that some proteins can passage the intestinal epithelium by transcytosis directly into the bloodstream. Thus, glycated protein present in food can be an additional source of glycotoxins. The aim of this study was to compare the affinity of native and glycated cystatin to the brush border membranes of rat kidney. Kinetic analysis was performed with surface plasmon resonance technique using sensor chip L1. Dissociation constants for native and glycated cystatin (Kd) were 2.76 μmol/L and 3.82 μmol/L, respectively. The results of our study indicate that glycation only slightly affects binding of cystatin to brush border membranes. This suggests that glycated cystatin and other glycated proteins may also be efficiently taken up in the kidney proximal tubule. The observation may be important for understanding the mechanisms involved in the development of diabetic nephropathy.  相似文献   

14.
An adhesion test for binding of porcine brush border membranes to Escherichia coli cells that possess the K88 antigen (K88+) has been developed using enzyme immunoassay procedures. K88 pilus protein or K88+ E. coli cells were immobilized in the wells of polystyrene microtitre plates. These plates were incubated in the presence of material obtained by scraping the villous surface of pig small intestines. Adhesion of membrane material to immobilized K88 was detected by adding rabbit anti-brush border IgG followed by urease-labelled sheep anti-rabbit IgG conjugate. Action of bound enzyme on urea/bromo-cresol purple substrate solution (pH 4.8) produced an intense colour change from yellow to purple, enabling the test to be read visually. This test enables simple, rapid testing of large numbers of intestial samples and gives results that agree well with the more cumbersome microscopic adhesion test for adhesion of K88+ E. coli to purified brush border membranes.  相似文献   

15.
试验选用60只健康的德国牧羊犬仔犬,共计10窝,随机将每窝仔犬分成2组,试验组20-30日龄饲喂混有3.2 g乳酸菌素的奶粉,30日龄断乳后继续饲喂混有3.2 g乳酸菌的饲料,与对照组进行比较。以此来研究日粮中添加乳酸菌对仔犬生长性能、发病率、肠道菌群的影响。结果表明:在日粮中添加乳酸菌可提高断乳仔犬生长性能,增重明显,饲料利用率提高;降低仔犬发病率、死亡率(P<0.05)及缩短腹泻时间;降低粪便pH值约0.3-0.5单位,使断乳前厌氧菌群呈优势分布,同时增加乳酸菌的含量、减少大肠杆菌的含量(P<0.05)。  相似文献   

16.
[Objective] The paper was to isolate and identify probiotics in the intestine of laying hens. [Method] The intestinal probiotics in laying hens at peak period were isolated using conventional separation methods; the physical and chemical properties of target strains and in vitro antibacterial effects were measured. Moreover, the safety test of chicks was conducted. [Result] Four strains of lactobacillus were isolated from the jejunum of laying hens, including Lactobacillus plantarum, Bacillus acidophilus, L. delbrueckii subsp. Delbrueckii and L. delbrueckii subsp. Lactis, and their inhibition zone diameters were 18.30, 16.07, 11.45, 17.26 mm, respectively. One strain of Lactobacillus, L. brevis, was isolated from the cecum, with the inhibition zone diameter of 10.26 mm. Three strains of bacillus were isolated from the cecum, including Bacillus subtilis, B. cereus and B. licheniformis, and their inhibition zone diameters were 9.25, 8.46 and 8.37 mm, respectively. Daily drinking 2 billion units of viable bacteria was the safe dosage for chicks. [Conclusion] Eight strains of probiotics had certain inhibitory effect on Escherichia coli O_2, and had no toxic side effects to chicks. Lactobacillus had strong antibacterial effect on E. coli O_2, while the antibacterial effect of bacillus was relatively weak.  相似文献   

17.
Purified brush border and basolateral membranes were isolated from homogenized intestinal enterocytes of Holstein steers by divalent cation precipitation followed by differential and sucrose density gradient centrifugation. Alkaline phosphatase and Na/K adenosine triphosphatase served as marker enzymes for the brush border and basolateral membranes, respectively. The brush border and basolateral membrane fractions were enriched 5.1- and 10.1-fold, respectively, over the cellular homogenate. Electron micrographs, obtained with transmission electron microscopy, confirmed the vesicular nature of the membranes and revealed that basolateral membrane vesicles generally were smaller and more irregular in shape than brush border membrane vesicles. The vesicular nature of isolated membrane preparations was confirmed with osmotic activity experiments. Enrichment of brush border and basolateral membrane fractions compared to the initial homogenate and the vesicular configuration of both preparations indicate that the isolated brush border and basolateral membrane preparations were suitable models for evaluating nutrient transport properties of bovine small intestine. The number of transport experiments possible per animal using the membrane vesicle technique is many times more efficient than some other in vitro techniques (i.e., intestinal rings or everted sacs).  相似文献   

18.
Ileal samples from 242 pigs, collected at 3 Michigan slaughterhouses, were studied to determine the prevalence of intestinal receptors for K99-positive Escherichia coli. A brush border adhesion test was used to identify the receptors. Of the 242 samples examined, receptors were demonstrated in 230 (95%). After storage of brush border preparations at 4 C, bacterial aggregates lacking identifiable brush border fragments were present in samples tested for adhesion, indicating that K99 receptors may be released from brush border membranes. Seemingly, most, if not all, pigs have intestinal receptors for K99 pili, and an inheritance pattern similar to that observed for K88 receptors probably does not exist for K99 receptors.  相似文献   

19.
Enteric infection with an attaching and effacing Escherichia coli was diagnosed in a puppy with protracted diarrhea. Extensive colonization of the small intestinal mucosa was observed by light and scanning electron microscopy and characteristic lesions of bacterial attachment of the brush border of the enterocytes were demonstrated by transmission electron microscopy. The E. coli strain isolated from the small intestine belonged to serotype O49:H10, did not produce any known E. coli enterotoxin or cytotoxin, was not invasive, and was negative for the known fimbrial colonization factors produced by animal and human enterotoxigenic E. coli. A positive immunoperoxidase reaction was obtained on the bacteria attached to the enterocytes with an anti-E. coli O49 antiserum.  相似文献   

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