益生屎肠球菌RS3的分离鉴定及增殖条件的优化

为筛选具有益生作用的乳酸菌,该研究从泡菜中筛选到1株细菌菌株RS3,经菌落形态观察、生化试验和16 S rRNA序列分析确定为屎肠球菌。为高效获得屎肠球菌RS3菌体,对其最佳增殖条件进行优化研究。利用单因素筛选和中心复合响应面试验对屎肠球菌RS3菌体增殖用液体培养基和增殖条件进行研究,优化的最佳培养基为乳糖15 g/L、胰蛋白胨25 g/L、初始pH值为8.2、培养温度37℃。与优化前培养条件相比,优化后培养条件下菌体生物量提高了54.9%,乳酸产量提高了53%,为后期规模化培养和益生菌剂开发奠定基础。     

屎肠球菌发酵特性及其功能性研究

探讨了分离自新疆酸奶疙瘩的一株屎肠球菌在乳制品应用中具有的潜在益生价值。通过测定滴定酸度、丁二酮、乙醛、游离氨基酸等指标,研究了屎肠球菌在脱脂乳中的发酵特性以及发酵乳上清液具有的抗氧化与抑菌功能。结果表明,屎肠球菌产酸、产香和降解酪蛋白能力强,37℃发酵24h,滴定酸度为123.55°T,丁二酮含量为12.31μg/mL,乙醛含量高达90.12μg/mL,游离氨基酸含量为331.92μg/mL,活菌数最高可达1.10×1010cfu/mL。发酵乳上清液对常见病原微生物有抑制作用,且抑菌物质具有热稳定性、较宽的pH范围、对蛋白酶敏感的特点,对羟自由基清除率为96.84%,超氧阴离子自由基清除率为31.33%,具有抗氧化能力。     

豆汁源屎肠球菌DZ的发酵特性及其安全性评估

本文以豆汁源屎肠球菌DZ为研究对象,从生长曲线、产酸能力、产粘能力及模拟人体胃肠道耐受性等方面探究其特性;通过吲哚实验,溶血实验,硝酸还原酶检测等实验探究其安全性,并进一步探究其发酵产品的安全性。结果表明,屎肠球菌DZ在1h-4 h时菌落生长较快;在p H 3.0的人工胃液中可存活,之后进入肠道可增殖;豆汁接菌发酵16 h时,酸度值达43.69°T,接菌发酵的豆汁酸度值差异极显著(p0.01);发酵时间为16 h时,粘度值达5.50 mPa·s且差异极显著(p0.01);在安全性探究实验中,硝酸还原酶检测及吲哚实验均为阴性,溶血性实验表明屎肠球菌DZ为γ-溶血;其发酵产品均未检出黄曲霉毒素、呕吐毒素等有害物质。结论说明,屎肠球菌DZ具备在极低p H值情况下存活的能力,产酸能力良好,且具备一定的产粘能力;该菌不分解色氨酸,不溶血,其代谢产物中不含硝酸还原酶,具有一定安全性。     

泡菜源屎肠球菌Enterococcus faecium R2的环境胁迫耐受性及安全性评价

屎肠球菌R2是分离于泡菜中的优势产酸菌,可高效利用豆腐黄浆水中的低聚糖产酸制备酸浆,可作为一种新型酸浆纯种发酵剂。该文通过毒力基因检测、万古霉素耐药基因筛查、有害代谢产物实验来评价屎肠球菌R2的安全性,并进一步研究该菌株对外界环境的耐受性,为生产一种新型酸浆纯种发酵剂奠定基础并为其实际生产应用提供科学基础。结果表明,屎肠球菌R2的毒力基因检测和万古霉素耐药基因筛查及有害代谢产物检测结果均为阴性,也不会产生溶血现象;该菌株对外界环境中的酸性、胆盐及高渗透压耐受性较好且具有一定的自聚集性和疏水性。由此可见屎肠球菌R2具有安全性。     

豆酱中产细菌素屎肠球菌的筛选及特性分析

从农家传统发酵豆酱中分离出164株疑似乳酸菌,其中有84株球菌。试验筛选到1株产细菌素的屎肠球菌R1并对其理化性质进行研究。该细菌素对金黄色葡萄球菌、单核细胞增生李斯特菌、大肠杆菌等具有较好的抑制作用,对酸和热稳定。经鉴定该细菌素种类为肠球菌素P。菌株R1在p H3.0模拟胃液中3 h存活率达86.35%,在模拟肠液中6 h存活率达87.72%,对人工消化液耐受性良好。药敏试验结果表明,菌株R1对青霉素、氨苄西林、环丙沙星、氯霉素和庆大霉素敏感,对诺氟沙星和红霉素不敏感,未检测出毒力因子,具有潜在安全性。     

屎肠球菌BC-3产细菌素条件优化及其理化特性研究

从东北传统发酵酸菜中筛选到一株屎肠球菌BC-3,通过其代谢产生的细菌素来控制食品中的某些腐败菌和病原菌,开发其作为高效广谱食品生物防腐剂。通过滤纸片法对屎肠球菌BC-3产生细菌素发酵条件进行优化,结果表明,发酵时间为20 h、pH值为6.5、接种量为1.5%、温度为37.0℃时,抑菌圈直径最大,为17.87 mm。经硫酸铵粗提后,对肠球菌素E3生物学特性进行分析,结果表明其具有较高耐热性,在pH为2.0~10.0的范围内稳定性较好,可被蛋白酶降解,经有机溶剂处理后稳定性几乎不受影响。     

屎肠球菌冷冻干燥保护剂筛选及稳定性比较研究

屎肠球菌在微生态产品中的应用效果受产品活菌量、贮存稳定性影响明显,为寻找适于屎肠球菌规模化生产的冻干保护剂,本研究通过正交试验设计,及屎肠球菌冷冻干燥保护剂4℃、37℃贮存稳定性比较,优化适合屎肠球菌的冻干保护剂配方为:脱脂乳5g/100mL、蔗糖1g/100mL、麦芽糊精5g/100mL。采用此保护剂配方制备的屎肠球菌冻干样品,在铝箔袋密封包装、温度37℃、相对湿度75%条件下存放4周,菌存活率为97.90%。     

屎肠球菌饲用效果及作用机理

屎肠球菌是动物肠道中的一种常见菌,它是一种兼性厌氧的乳酸菌,具有良好的耐酸、耐胆盐和耐热性,能够抑制肠道致病菌增殖,如大肠杆菌和沙门氏菌,医学上屎肠球菌制剂常被用来治疗腹泻。结合我们有关屎肠球菌影响仔猪肠道基因表达的最新研究结果,重点综述了屎肠球菌在饲料中的应用效果及作用机理。     

产酪胺粪肠球菌和屎肠球菌PCR检测方法的建立

目的：建立快速简便地检测产酪胺粪肠球菌(Enterococcus faecalis)和屎肠球菌(Enterococcus faecium)的PCR方法。方法：将粪肠球菌和屎肠球菌的酪氨酸脱羧酶基因与GenBank数据库中已公布的细菌的酪氨酸脱羧酶基因进行比对,根据它们的非保守序列,分别设计粪肠球菌和屎肠球菌的特异性引物,建立检测产酪胺粪肠球菌和屎肠球菌的PCR方法。结果：根据非保守序列,分别设计粪肠球菌和屎肠球菌的特异性引物,用27株细菌对这两对引物分别进行反复验证,结果显示,所设计的两对引物都只对其目的菌株产生特异性扩增,对其他菌株没有扩增,方法的检测限可达到1.0×102CFU/mL。结论：本方法具有良好的特异性、稳定性和灵敏性,可用作食品中产酪胺粪肠球菌和屎肠球菌的检测。     

粪肠球菌(Enterococcus faecalis)和屎肠球菌(Enterococcus faecium)产生物胺交互作用研究

粪肠球菌和屎肠球菌是发酵香肠中常检出的2种主要的产酪胺和苯乙胺微生物。将粪肠球菌和屎肠球菌按照不同比例进行混合接种培养,发现在48h连续培养过程中,当粪肠球菌和屎肠球菌以1∶9比例混和接种培养时,体系pH值、细菌数量和酪胺生成量均显著低于其他各处理组;粪肠球菌有很强的产苯乙胺能力而屎肠球菌产苯乙胺能力较弱,当两者混合接种培养时,各混合体系的产苯乙胺水平相当,屎肠球菌产苯乙胺能力不受影响,而粪肠球菌产苯乙胺能力显著降低。     

Relation of Enterococcus faecalis and Enterococcus faecium isolates from foods and clinical specimens

Clinical Enterococcus faecalis (n=65) and Enterococcus faecium (n=12) blood isolates from three Swiss hospitals were characterized with testing for resistance to antimicrobial agents, pulsed-field gel electrophoresis (PFGE), and the occurrence of virulence factors. Phenotypic determination of resistance to antimicrobial agents resulted in 20% of E. faecalis isolates showing a triple resistance against chloramphenicol, tetracycline, erythromycin, and seven isolates (two E. faecalis and five E. faecium) exhibiting a multiresistance against five or more antimicrobials. One isolate each of E. faecalis and E. faecium showed vancomycin resistance. All isolates contained at least two of the nine tested virulence genes (agg, gelE, cyl, esp, efaAfs, efaAfm, cpd, cob, and ccf). Phylogenetic analysis of the PFGE profiles identified several small clusters within E. faecalis isolates, one of which included isolates of all three hospitals. Fifty-six (73%) isolates occurred as unique, patient-specific clones. Several PFGE types were associated with shared features in their resistance patterns, indicating spread between and within wards. Finally, enterococci from this study and previous isolates from cheeses were examined by PFGE typing. The comparison of PFGE profiles from human and food isolates resulted in clusters of genetically strong related strains, which suggests high similarities of the enterococcal community composition of these two environments. A possible spread of the enterococcal isolates through the food supply cannot be excluded.     

屎肠球菌源谷氨酸脱羧酶的制备及其酶学性质研究

为了开发谷氨酸脱羧酶(glutamate decarboxylase,GAD),以Enterococcus faecium为gadB基因供体、纤维素结合域(cellulose-binding domain,CBD)为亲和标签,利用内含肽DnaB自剪切作用分离GAD,对融合酶CBD-DnaB-GAD的构建、表达、GAD纯...     

一种抗猪链球菌细菌素的生物学特性研究

为了开发新型天然抗菌物质,本研究以猪粪便中分离出的一株产抗猪链球菌细菌素产生菌屎肠球菌LPL420P06为试材,对其产生的细菌素进行了理化特性研究。结果表明,该细菌素具有良好的热稳定性,在90℃、30min热处理的条件下仍能保持90%以上的活性;易被胰蛋白酶、蛋白酶K、木瓜蛋白酶、中性蛋白酶失活,表明该细菌素是一类蛋白类物质;在pH5～9范围内37℃、4h处理,活性保持稳定;抑菌谱实验结果表明,该细菌素不仅对单增李斯特氏菌、金黄色葡萄球菌、猪链球菌等多种革兰氏阳性病原菌有明显的抑制作用,而且对沙门氏菌、大肠杆菌等部分革兰氏阴性菌有不同程度的抑制作用,显示出该细菌素具有很好的开发应用前景。     

Growth and energy generation by Enterococcus faecium FAIR-E 198 during citrate metabolism

Citrate metabolism by Enterococcus faecium FAIR-E 198, isolated from Greek Feta cheese, was studied in various growth media containing citrate either in the presence of glucose, or as the sole carbon source, both under aerobic and anaerobic conditions. In de Man-Rogosa-Sharpe (MRS) broth with increasing citrate concentrations, cometabolism of citrate and glucose took place. Glucose was stoichiometrically converted into lactate, while citrate into acetate. Glucose consumption and biomass yield were enhanced with increasing initial citrate concentrations, even though maximum specific growth rate was not. When citrate was used as the sole carbon source in increasing initial concentrations, the main end product was acetate. Small amounts of lactate, formate, ethanol, and acetoin were also produced. In all cases, no significant differences were observed between aerobic and anaerobic conditions. However, when citrate was used as sole carbon source, formate production was favored in the absence of oxygen. The present work shows that E. faecium is able to utilize citrate in synthetic media, either in the presence of glucose or as the sole carbon source, resulting in energy production and the formation of aroma compounds.     

动物性食品源大肠杆菌耐药性研究

目的:近年食源致病菌及指示菌的耐药性已引起有关人员的重视,本文旨在了解动物性食品源大肠杆菌(E coli)的耐药情况,为其耐药性的安全评价提供依据.方法:采用NCCLS推荐的肉汤微量稀释法,对源自动物性食品中的319株大肠杆菌做25种抗生素(组合)的敏感性实验.结果:319株大肠杆菌对喹诺酮类(93.00％～100％)、利福平(98.75％)、多黏菌素E(75.20％)和链霉素(75.60％)的耐药率较高,共产生87种耐药谱,多重耐药率为100％.其中个别菌株耐药物高达20种.结论:动物性食品中大肠杆菌耐药情况严重,应加强其耐药性监测与控制.     

Genetic diversity of Enterococcus faecium isolated from Bryndza cheese

One hundred and seventy-six Enterococcus faecium isolates from Slovak dairy product Bryndza were tested for the presence of plasmid DNA. Eighty-two isolates were positive and their plasmid DNA was isolated and digested by EcoRI and HindIII restriction endonucleases. The patterns obtained were compared with those obtained after pulsed-field gel electrophoresis of macrorestriction fragments (PFGE), (GTG)(5)-PCR and ERIC-PCR. All these molecular approaches were applied for the study of genetic variability and determination of strain relatednesses among plasmid-positive isolates of E. faecium. In general, all methods revealed a considerable genetic diversity of E. faecium isolates. Plasmid profiling and ERIC-PCR have offered a higher resolution than PFGE and (GTG)(5)-PCR.