羊源肠球菌溶血素特性分析及其对兔红细胞作用的观察

对致羔羊脑炎肠球菌E129-3菌株溶血素进行检测分析，并利用光学显微镜和电子显微镜观察其对兔红细胞的作用，探讨了肠球菌溶血素的特性及溶血类型。结果表明，小白鼠、兔、犬红细胞对该溶血素最敏感，牛红细胞不敏感。该溶血素可以被DTT、Ca^2＋活化，被蛋白酶K、EDTA、Zn^2＋、Cu^2＋抑制。在培养后2h，细胞浆内着色不一致或密度降低，5h时红细胞数量明显减少，细胞膜较完整。提示，肠球菌溶血素为成孔蛋白类溶血素。     

Prevalence of vancomycin-resistant Enterococcus faecium (VREF) in pig faeces from slaughterhouses in Spain

A study to estimate the prevalence of vancomycin-resistant Enterococcus faecium in faecal samples from pigs at slaughterhouses in Spain was carried out between November 1998 and January 1999 with 900 samples taken from four abattoirs representing 9.7% of all pig slaughtered in 1998. Using a selective enrichment broth with vancomycin (8 μg/ml), 64 samples (7.1%; 95% CI: 5.5, 9.0%) had E. faecium vancomycin-resistant strains that showed minimal inhibitory concentrations of 256 μg/ml (62 strains) and 512 μg/ml (two strains). Results by farm showed that 43 of the 240 pig farms represented in the sampling had at least one faecal sample with vancomycin-resistant E. faecium.     

日粮中添加屎肠球菌对AA肉鸡生产性能、免疫器官指数和血液脂质代谢相关指标的影响

本试验旨在研究日粮中添加屎肠球菌对AA肉鸡生产性能、免疫器官指数和血液脂质代谢相关指标的影响，探讨屎肠球菌替代抗生素在肉鸡日粮中应用的可行性及其最适添加量。试验选取1日龄AA肉鸡公仔鸡600只（50 g/只），随机分成5组，每组6个重复，每个重复20只鸡。对照组（CON）饲喂基础日粮；抗生素组（ANT）饲喂基础日粮+0.1%金霉素；3个屎肠球菌试验组（LEF、MEF和HEF组）在基础日粮中分别添加50、100、200 mg/kg屎肠球菌。试验分2期，分别为1~21日龄（前期）和22~42日龄（后期）。结果显示：①各试验组肉鸡生长性能与CON组相比均无显著差异（P>0.05）；从饲养全期看，MEF组和HEF组AA肉鸡的死淘率最低。②在饲养后期，与CON组相比，MEF组胸腺指数显著提高（P<0.05），MEF组脾脏指数有提高的趋势（0.05 < P < 0.1）。③在饲养前期，与CON组和ANT组相比，LEF组和HEF组血清总胆固醇（TC）含量极显著降低（P<0.01）；与ANT组相比，LEF组和MEF组血清甘油三酯（TG）含量极显著降低（P<0.01）；与CON组相比，MEF组和HEF组血清高密度脂蛋白（HDL）含量极显著提高（P<0.01）；与ANT组相比，添加屎肠球菌试验组的低密度脂蛋白（LDL）含量极显著降低（P<0.01）。在饲养后期，与CON组和ANT组相比，LEF组肉鸡血清中TG含量极显著降低（P<0.01），LEF组和MEF组HDL含量极显著提高（P<0.01）。综上所述，在肉鸡饲养中，添加屎肠球菌可以在一定程度上降低死淘率，并有促进免疫器官发育的趋势，还具有一定的降低血脂的作用。综合考虑，建议在AA肉鸡日粮中添加100 mg/kg屎肠球菌。     

Detection on Biofilm and Biofilm-associated Genes of Enterococcus faecalis Inducing Lamb Encephalitis

The purpose of this study was to observe and analyze the ability of biofilm formation of the Enterococcus faecalis (E.faecalis) XJ05 and to detect if the E.faecalis which could induce lamb encephalitis carried the biofilm-associated genes. The E.faecalis XJ05 was used as the sample. The biofilm model was established by the 96-well microtiter plate and read by microplate reader in the D_{595 nm} at the same time observed by the inverted microscope. The primers were designed to examine if the 11 strains of E.faecalis carried the biofilm related genes and then the amplified products were sequenced and analyzed for homology. The results showed that the amount of BF produce in XJ05 strain was significantly different from blank control group at different time (P<0.05), and the highest D_{595 nm} value was at 24 h and significant difference compared with other time (P<0.05). The biofilm of 6 h was scattered when observed under the microscope and the time between 12 to 24 h biofilm to be more denser, after 24 h the biofilm became to degradate and loose gradually. It turned out that the 11 strains of bacteria carried different biofilm-associated genes, 8 biofilm-associated genes were found in 6 strains of bacteria, 7 biofilm-associated genes were find in 1 strain of bacterium, 6 biofilm-associated genes were found in 1 strain of bacterium, 2 biofilm-associated genes were found in 1 strain of bacterium, 2 strains of bacteria could not text out anyone of the detected genes.The homology of all detected genes were all between 93.3% to 100.0%. It concluded that the E.faecalis XJ05 could form the completed biofilm and there were 9 kinds carried the biofilm-associated genes in 11 strains of E.faecalis.     

肉牛运输前后牛源肠球菌的分离鉴定及其耐药基因检测

为探讨肉牛运输应激综合征的潜在致病菌,本试验采集肉牛运输前后的粪便和血液,针对牛源肠球菌进行分离鉴定、药敏试验和耐药基因检测。结果检出45株肠球菌（粪便中34株,血液中11株）,且对克林霉素等不敏感,其中携带耐药基因aac（6’）／aph（2＂）阳性菌株14株（阳性率31.1%）和ant（6）-Ⅰ的阳性菌株9株（阳性率20%）。表明肉牛经过长途运输后易被携带耐药基因的肠球菌侵入。     

豆腐(豆浆)中屎肠球菌生长的温度预测模型

采用预测食品微生物学的方法研究了豆腐(豆浆)中主要腐败微生物屎肠球菌的生长规律，建立了屎肠球菌在豆浆培养基中的初级和二级预测模型，研究了0—55℃屎肠球菌的生长曲线。结果表明，在适温阶段屎肠球菌的生长曲线呈典型的S形，适合用Gompertz模型拟合；当温度接近最低生长温度和最高生长温度时，适合用线性回归方程拟合。屎肠球菌在立浆中生长的温度模型符合Ratkowsky3式。根据预测模型，屎肠球菌的最低生长温度为4．8℃，最高生长温度为54.6℃，最适生长温度为4l℃。对模型进行了验证。     

我国18个省份猪源肠球菌耐药调查及分析

为研究我国猪源肠球菌的耐药情况,本研究采集18个省市猪养殖场的粪便样品836份进行了肠球菌的分离鉴定,并通过琼脂稀释法测定11种抗菌药物的最小抑菌浓度。结果显示:从836份样品中共分离出225株肠球菌,其中屎肠球菌106株,粪肠球菌56株,小肠肠球菌34株,鹑鸡肠球菌17株,铅黄肠球菌7株,坚忍肠球菌4株,Enterococcus thailandicus 1株。所有的肠球菌对被检抗菌药物耐药程度由高到低依次是四环素(98.2%)、阿米卡星(94.7%)、多西环素(89.3%)、米诺环素(88.9%)、氟苯尼考(88.4%)、红霉素(86.2%)、环丙沙星(63.1%)、氨苄西林(33.8%)、氯霉素(29.8%),未检测到万古霉素和利奈唑胺耐药菌株。除氨苄西林、万古霉素、利奈唑胺外,粪肠球菌对其余8种被检抗菌药物耐药率均高于屎肠球菌。小肠肠球菌对阿米卡星、红霉素、四环素、多西环素、米诺环素5种抗菌药物的耐药率高于屎肠球菌。肠球菌的多重耐药情况集中在6耐、7耐和8耐,占肠球菌总数的72.9%。本研究表明我国猪源肠球菌对常见抗菌药物耐药率较高,应引起更多关注。     

5 L发酵罐中粪肠球菌发酵工艺参数优化

本试验旨在通过单因素试验及Box-Behnken响应面试验设计法优化饲用粪肠球菌EXW 27发酵工艺,探索搅拌速度、中和剂、pH、接种量、初始糖含量、通气方式以及补料工艺等对菌体在发酵罐内生长的影响。优化菌体小试发酵工艺为:将种子液以3%(V/V)接种于装液量为70%的5 L小罐,发酵温度37℃,搅拌转速165 r/min,通空气保压0.02 Mpa,自动流加12.5%的氨水控制pH在5.5,当pH高于5.5流加葡萄糖补料发酵18 h左右结束,在此最佳条件下所得发酵液的活菌浓度约为3.799×10^10 cfu/mL,比优化前提高了近3倍,为以后工业化生产提供参考。     

猪源屎肠球菌tetM基因的检测

用微量肉汤倍比稀释法测定了猪源屎肠球菌对四环素等抗生素的敏感性,用PCR和DNA测序方法检测了屎肠球菌中四环素类耐药基因(tet基因),并分析了试验菌对四环素类的耐药机制。结果表明:14株猪源屎肠球菌对四环素、多西环素、环丙沙星、红霉素全部耐药,4株对头孢噻呋耐药;在14株屎肠球菌中,分别有13株和9株含tet L和tet M基因,其中有9株同时携带tet L和tet M基因;猪源屎肠球菌主要存在主动外排和核糖体保护两种耐药机制,其对四环素类的耐药性主要与携带tet M和tet L有关。