粪肠球菌fsr群体感应系统的研究进展

群体感应系统是微生物间交流和适应周围环境的一种机制。粪肠球菌fsr群体感应系统与粪肠球菌致病性密切相关。综述了粪肠球菌fsr群体感应系统的组成,各部分特点,群体感应系统信号调控通路,fsr群体感应系统相关毒力基因,群体感应系统抑制剂等国内外研究进展,并对粪肠球菌所引起疾病的治疗提出新的建议。     

屎肠球菌新序列型ST989菌株的分离鉴定及多重耐药性分析

试验从青海民和县某羊场致病性感染半月龄羔羊中分离出革兰氏阳性菌,感染羔羊临床症状有精神萎靡,采食减少,发病1~2 h后死亡。两只濒死羔羊剖检结果发现,其中一只出现肝脏肿大及肝包膜脱落,其余脏器无明显病理变化;另一只各脏器均未发现病理变化。分离病料,革兰氏染色发现,从病料中分离到的细菌均为革兰氏阳性球菌。对分离菌株进行Tuf基因PCR扩增,BLASTn比对结果显示与屎肠球菌AUS0085核苷酸序列相似性为99.8%,据此初步确定这些菌株为屎肠球菌。药敏试验结果表明,这些菌株可分为两类,第1类对β-内酰胺类、氨基糖苷类、大环内酯类、四环素类、喹诺酮类、利福霉素类抗生素及林可霉素和克林霉素耐药,对氯霉素和万古霉素敏感;第2类对β-内酰胺类、氨基糖苷类、四环素类、喹诺酮类、利福霉素类抗生素耐药,对红霉素和罗红霉素中度耐药,但对克拉霉素、阿奇霉素、克林霉素、林可霉素、氯霉素和万古霉素敏感。对第1类耐药性代表菌株lby1和第2类耐药性代表菌株lbg3进行多位点序列分析(MLST),结果发现这些菌株为一个屎肠球菌的新序列型,为ST989。系统进化树结果显示屎肠球菌lbg3与屎肠球菌ST468亲缘关系最近,致病力试验结果表明屎肠球菌lby1和lbg3均具有致病性。     

Classification and Antimicrobial Susceptibilities of Enterococcus Species Isolated from Apparently Healthy Food‐Producing Animals in Japan

Summary A total of 1024 enterococci were recovered from faeces of healthy animals from 178 cattle, 178 pig and 156 broiler farms. Enterococcus faecium was the predominant species recovered (35.8%), followed by E. faecalis (31.3%) and E. hirae (25.6%). Oxytetracycline resistance was most frequently found among E. faecalis (85.9%), E. faecium (58.8%) and E. hirae (48.1%). Resistance rates to almost all antimicrobials were higher in E. faecalis than E. faecium and E. hirae. Isolates from cattle were more susceptible to the antimicrobials studied than those from pigs and broilers. VanA‐ or VanB‐type vancomycin‐resistant enterococci have not been found since the ban of avoparcin use 5 years ago.     

2株猪源益生性肠球菌对酸和胆盐及热的耐受性研究

为了筛选动物肠道中的有益优势菌,研究了2株分离自猪肠道的益生性屎肠球菌(E1,E7)的耐受特性。本试验设pH 2,2.5,3,4的4个处理组,以pH 7为对照组;设胆盐浓度分别为0.2%,0.4%,0.6%,0.8%,1%的5个处理组,以不含胆盐的培养液为对照组;温度设50,80,90℃,以37℃为对照,分别作用5,10,15,20 min,经该3种方法处理后各取100μL培养液用细菌稀释计数法测定活菌数。结果表明:E1,E7都有较强的耐酸能力,在pH 2时,作用2 h后仍能检测到活菌。胆盐浓度达到0.4%时,E1,E7仍有一定的耐受能力,随胆盐浓度升高至0.6%时,活菌数由108.2CFU/mL降到102.5CFU/mL。2菌株在不同温度下经不同作用时间处理后呈不同的生长态势。     

Effect of probiotics, Enteroccus faecium, on tilapia (Oreochromis niloticus) growth performance and immune response

The aim of this study was to analyze the effect of a probiotic bacterium, Enterococcus faecium ZJ4 on growth performances and immune responses of tilapia (Oreochromis niloticus). The tilapias were treated with E. faecium ZJ4 at a final concentration of 1 × 10⁷ cfu ml^− 1 in aquaria water every 4 days. Six aquaria with three replicates for treated and controls were used. After 40 days, the tilapias supplemented with the probiotic showed significantly better final weight and daily weight gain (DWG) than those fed the basal diet (Control) (P < 0.05). There was no remarkable difference (P > 0.05) in the total serum protein, albumin content, globulin concentration and A/G ratio between the treated and control tilapias. The result of lysozyme activity assay was similar to these biochemical indexes. However, the complement component 3 content, myeloperoxidase (MPO) activity and the respiratory burst activity of blood phagocytes were higher (P < 0.05) in E. faecium treated tilapias (trial 1) than the controls.     

养殖废水中异养硝化细菌的分离筛选和鉴定

为了获得脱氮功能强的异养硝化菌株用于养殖废水的脱氮处理,通过富集、分离和纯化等步骤,并结合格利斯试剂检验菌株硝化能力的方法,从某养猪场污水处理池污泥中分离筛选了4株具异养硝化功能的菌株,分别标号为79、84、L116、L117,通过16SrDNA序列分析和美国全自动微生物分析仪Biolog鉴定,4株菌均为粪产碱杆菌（Alcaligenesfaecalis）,并验证了这4株菌的硝化能力。结果表明,当液体培养基初始氨氮浓度为90mg.L-1左右时,在振荡培养48h内,菌株79、84、L116、L117培养基中氨氮和总氮均快速下降,氨氮去除率分别达到44.4%、47.9%、61.3%和56.4%,总氮（除菌）去除率达到39.9%、38.5%、43.4%和40.7%。     

应用16S rRNA基因序列分析鉴定猪源肠球菌

对河南省不同地区病猪分离的11株疑似肠球菌提取基因组DNA,PCR扩增16SrRNA基因片段,经克隆后测序,并与GenBank中注册的相关肠球菌菌株的16SrRNA基因序列进行比较、绘制系统发育树,进行鉴定。结果表明,4株临床分离株鉴定为粪肠球菌（E.faecalis）,7株为屎肠球菌（E.faecium）。首次从分子水平上证实了猪肠球菌在河南省的存在,为临床诊断及分子鉴定提供依据。     

宠物源菌株的分离鉴定及耐药性分析

为了解河南郑州市常见宠物携带菌株组成以及耐药情况,本试验采集了郑州地区不同宠物医院患病及健康犬、猫共计76个样本的肛拭子、眼拭子、耳拭子。试验通过细菌分离培养、形态学观察、生化试验、16s rRNA基因测序完成细菌鉴定,确定分离菌株种类,采用微量肉汤稀释法测定分离菌株耐药表型。结果共分离得到大肠杆菌50株、肠球菌27株、奇异变形杆菌24株、葡萄球菌46株、绿脓杆菌4株。奇异变形杆菌耐药最为严重,对多西环素、替米考星两种药物耐药率高于90.0%;大肠杆菌对替米考星的耐药率高达94.0%,对阿莫西林耐药率为62.0%,对多西环素、多粘菌素E、庆大霉素、环丙沙星、恩诺沙星、头孢噻呋的耐药率在4.0%~24.0%之间。肠球菌对多西环素、庆大霉素、头孢噻呋三种药物的耐药率在29.6%~40.7%之间;对阿莫西林、恩诺沙星、环丙沙星三种药物的耐药率在7.4%~14.8%之间,对替米考星的耐药率为66.7%。葡萄球菌对替米考星的耐药率为39.1%,对阿莫西林、多西环素、庆大霉素、环丙沙星、恩诺沙星、头孢噻呋的耐药率均低于20.0%。上述试验结果表明:大肠杆菌和葡萄球菌在宠物菌群组成中占比较大;大肠杆菌和奇异变形杆菌的耐药情况较为严重。     

二氧化氯（ClO2）在桑叶消毒上的应用研究

为探讨二氧化氯（ClO2）对桑叶质量、家蚕微孢子虫和肠球菌的灭活作用及其稳定性、腐蚀性,以直接喷洒桑园桑叶和浸泡离体桑叶消毒的方式,测定ClO2对桑叶质量的影响,并用悬液法和桑叶片载体法处理家蚕微孢子虫,测定ClO2对微孢子虫的灭活效果。结果显示,浓度在500 mg/L以下的ClO2溶液对桑叶质量无显著影响;采用悬液法时,30 mg/L ClO2溶液处理6.0 min即可达到完全杀灭家蚕微孢子虫的效果,而漂白粉精浓度需要达到0.24%才具有同等效果;采用桑叶片载体法时,300 mg/L ClO2溶液处理10.0 min可达到完全杀灭家蚕微孢子虫的效果。以10 mg/L ClO2溶液处理1.0 min,可完全杀灭家蚕肠球菌。ClO2稳定性较差,对金属具有中度腐蚀性。可见,ClO2适合作为桑叶消毒剂用于预防家蚕微粒子病的发生。     

单一益生菌(屎肠球菌)介导的断奶仔猪肠道菌群变化规律

通过细菌16SrRNA基因的高通量测序,对断奶仔猪的肠道菌群结构和饲喂两株单一益生菌(屎肠球菌)后肠道菌群的变化情况和规律进行分析。结果显示,断奶仔猪肠道微生态中拟杆菌门Bacteroidetes和厚壁菌门Firmicutes的细菌所占比例分别为50.5%和42.2%,为绝对优势菌群。饲喂屎肠球菌后,肠道菌群的多样性和细菌丰度均增加;厚壁菌门Firmicutes,变形菌门Proteobacteria、无壁菌门Tenericutes、酸杆菌门Actidobacteria、芽单胞菌门Gemmatimonadetes、放线菌门Actinobacteria细菌的丰度明显上升,而拟杆菌门Bacteroidetes的细菌丰度则发生了明显下降。屎肠球菌所在的肠球菌属Enterococcus的比例虽由0.07%(对照组)上升至0.12%(SF1组)和0.14%(SF2组),但在肠道菌群中所占比例仍然很小,说明屎肠球菌对仔猪肠道微生态的作用主要是影响其他细菌的丰度和多样性进而改变菌群结构。与对照组相比,SF1组的上述菌群变化幅度高于SF2组,通过与3组仔猪生长性能数据的对比,上述菌群变化的幅度与仔猪生长性能提高的程度呈现正相关。