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1.
为了给表达高活性的抗菌肽Hadrurin提供开发应用的依据,进一步为用基因工程方法生产具有多种生物活性的抗菌肽Hadrurin蛋白提供研究基础,本研究表达获得重组抗菌肽Hadrurin(rHadrurin)蛋白的基础上,将纯化的rHadrurin蛋白进行肠激酶酶切,恢复其天然活性结构。用最小抑菌浓度(MIC)和最小杀菌浓度(MBC)方法检测抗菌肽Hadrurin在不同剂量、不同pH值、不同保存温度下对鸡致病性大肠杆菌和金黄色葡萄球菌的抑菌活性及杀菌活性。并以小鼠为动物模型,进行抗菌肽rHadrurind对小鼠的体内保护实验。结果表明抗菌肽rHadrurin对上述细菌的最小抑菌范围为1.32μg/mL～4.32μg/mL,最小杀菌范围为1.77μg/mL～8.54μg/mL,而且-70℃～100℃及在pH3～pH10条件下仍具有高效抗菌活性。240μg/只剂量的抗菌肽蛋白可有效预防保护小鼠免受致死剂量鸡致病性大肠杆菌攻击,320μg/只剂量可达到保护率85%以上。 相似文献
2.
Unsupplemented porcine colostrum and milk exhibited a powerful bactericidal effect for porcine strains of E coli incubated in vitro at 37 degrees C. This activity was independent of complement but was susceptible to acid pH, to the presence of soluble iron and to the selective immunoprecipitation of IgG, IgA and IgM. Manifestation of bactericidal activity required bacteria in an active state of metabolism and the length of incubation was an important factor in demonstrating the quality of the anticoli activity, ie, proliferation-inhibitory, bacteriostatic or bactericidal. Whey obtained by acid precipitation or by the application of rennin was devoid of bactericidal activity but was capable of slowing down proliferation of E coli. There was no correlation between lysozyme and anticoli activity although the complete removal of lysozyme by adsorption on to bentonite reduced bactericidal titres. With very few exceptions the highest bactericidal titres were recorded for colostrum, but even 28 days post partum about one half of 22 undiluted milk samples exhibired bactericidal activity. 相似文献
3.
P Rainard 《Veterinary microbiology》1987,13(2):159-166
The antibacterial activity of milk against a virulent strain of Escherichia coli was investigated using milk fractions from normal or inflamed glands. Mastitic whey exhibited either bactericidal or bacteriostatic activities, depending on whether bacteria were enumerated by the pour plate technique or by surface plating onto sheep blood agar. The former activity was not due to lactoferrin (Lf), which never exerted bactericidal activity, even when assayed in distilled water. Milk whey ultrafiltrate (UF) (mol. wt. less than 5000 d) was used to assay the ability of normal and mastitic milk to support the antibacterial activities of Lf against a strain of E. coli. The addition of purified Lf to UF from mastitic whey resulted in bacteriostasis, whereas Lf was without effect in UF from normal whey. It was concluded that Lf can actually slow down the growth of Lf-sensitive bacteria during mastitis, provided that plasma exudation takes place. 相似文献
4.
研究天然化合物肉桂醛对奶牛乳房炎主要致病菌——大肠杆菌、金黄色葡萄球菌和链球菌的抑菌效果。采用试管二倍稀释法测得肉桂醛对奶牛乳房炎主要致病菌金黄色葡萄球菌和标准金黄色葡萄球菌的体外最小抑菌浓度(MIC)分别为3.2 mmol/L和1.6 mmol/L;链球菌1.6 mmol/L;大肠杆菌和标准大肠杆菌6.4 mmol/L和3.2 mmol/L,且能完全抑制这三种菌的生长。肉桂醛的最小杀菌浓度(MBC)金黄色葡萄球菌和标准金黄色葡萄球菌分别为25.6 mmol/L和12.8 mmol/L;链球菌12.8 mmol/L;大肠杆菌和标准大肠杆菌25.6 mmol/L和12.8 mmol/L;在7 h内能有效杀灭这三种菌,肉桂醛对奶牛乳房炎主要致病菌有抑菌和杀菌能力,是一种潜在的奶牛乳房炎的临床治疗药物。 相似文献
5.
试验旨在研究抗菌肽BSN-37的抑菌活性和稳定性。采用微量倍比稀释法测定抗菌肽BSN-37的最小抑菌浓度(MIC),菌落计数法分析抗菌肽BSN-37对大肠杆菌CVCC1568的杀菌动力学特征,扩散法测定抗菌肽BSN-37的盐离子稳定性、酸碱稳定性、血清稳定性、胰酶稳定性、热稳定性、反复冻融稳定性、室温保持稳定性、药效保持时间稳定性。结果显示,抗菌肽BSN-37对革兰氏阴性菌(大肠杆菌和沙门氏菌)的MIC为1.5625～25μg/mL,对革兰氏阳性菌(枯草芽孢杆菌和短小芽孢杆菌)的MIC为1.5625～12.5μg/mL,对真菌(白色念珠菌)没有活性;抗菌肽BSN-37可在90min内完全杀灭大肠杆菌CVCC1568;除了Fe2+和胰酶会影响抗菌肽BSN-37的抑菌活性外,在75～100℃的高温、150～250mmol/L高浓度盐离子(Na+、K+、Ca2+和Mg2+)、20%～25%饱和浓度的Cu2+、pH 4～10、20%～25%的血清、10～12次的反复冻融、10～12d室温保存等条件下仍能保持较好的抑菌活性,药效保持时间可达7.5d。本试验结果表明,抗菌肽BSN-37具有替代抗生素成为新抗菌药物的潜力,为抗菌肽BSN-37的临床应用提供了理论依据。 相似文献
6.
7.
芽孢杆菌B13的分离鉴定及其抑菌作用研究 总被引：1，自引：0，他引：1
试验旨在发掘有效的抗性菌以替代部分抗生素,并研究其抑菌作用,以大肠杆菌K88、鼠伤寒沙门氏菌和金黄色葡萄球菌为指示菌,采用凝胶打孔法从猪肠道内容物中筛选出一株对3种病原菌均具有抑菌活性的菌株,利用形态特征观察、革兰氏染色、16SrDNA序列同源性比对鉴定菌株,并对其抑菌条件和生长条件进行优化。结果显示,试验筛选到1株对大肠杆菌K88、鼠伤寒沙门氏菌和金黄色葡萄球菌均具有较强抑制作用的菌株,经鉴定确定其为芽孢杆菌(Bacillus sp.),并命名为芽孢杆菌B13。此分离菌为革兰氏阳性菌,单生或成对生长。生长试验结果表明,该分离菌在pH为6.0,温度为34℃,以蔗糖为碳源、蛋白胨为氮源时,生长速度最快;在pH为7.0,温度为35℃,以麦芽糖为碳源、蛋白胨为氮源时,抗鼠伤寒沙门氏菌、黄色葡萄球菌和大肠杆菌K88活性最高。本试验通过对芽孢杆菌B13的特性进行研究发现,此菌株具有较好的抑菌效果,在抑菌方面具有良好的开发应用前景。 相似文献
8.
Kmet V Lucchini F 《Zentralblatt für Veterin?rmedizin. Reihe B. Journal of veterinary medicine. Series B》1999,46(10):683-687
A total of 20 strains of lactobacilli were isolated from the oesophagus and vagina of 20 sows at the time of partus. Aggregation activity was seen between six homofermentative autoaggregative lactobacilli and three strains of pathogenic Escherichia coli with F4, F5 and F6 fimbriae. The highest aggregation activity was observed between vaginal Lactobacillus acidophilus PV 32 or oesophageal OE 2/1 and E. coli with F4 (K88). The presence of aggregation-promoting factor (APF) was confirmed by polymerase chain reaction (PCR) with primers of a specific fragment the apf gene derived from human L. gasseri 4B2 in one oesophageal L. acidophilus strain OE 2/1. We propose that autoaggregative lactobacilli that aggregate with diarrhoeagenic E. coli can express a class of APF proteins that exhibit the function of an aggregation mediator. 相似文献
9.
为评价石榴皮止泻散的体外抑菌效果，将石榴皮止泻散制成水煎液，采用平板法进行体外抑菌试验，并采用试管稀释法测定其最小抑菌浓度(MIC)和最小杀菌浓度(MBC)。结果显示，平板法体外抑菌试验中每1 mL含1 g生药的石榴皮止泻散水煎液孔周围有明显的抑菌圈，平均抑菌圈直径分别为14.0和15.7 mm;试管稀释法测定石榴皮止泻散对大肠杆菌的MIC为25 mg/mL,MBC为50 mg/mL。结论，石榴皮止泻散水煎液在体外对大肠杆菌具有抑制和杀灭作用。 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.
OBJECTIVE: To determine the antibacterial activity of bovine lactoferrin hydrolysate (bLf-lysate) alone or in combination with other antimicrobials against antimicrobial-resistant Escherichia coli strains isolated from baby pigs. SAMPLE POPULATION: 3 clinical strains of E coli were isolated from baby pigs with severe diarrhea and designated as strains 9061, 9062, and 9065. PROCEDURE: The broth microdilution checkerboard and fractional inhibitory (or bactericidal) concentration index were used to evaluate the antibacterial effect elicited by bLf-lysate in combination with kanamycin, gentamicin, cephalothin, cefamandole, penicillin G, ampicillin, tetracycline, erythromycin, or rifampicin against the 3 strains of E coli. RESULTS: The 3 strains of E coli were susceptible to gentamicin and rifampicin but highly resistant to most of the other antimicrobials tested, except for strain 9061 that was also susceptible to cephalothin but intermediately inhibited by kanamycin and cefamandole. Synergistic growth-inhibitory activity was observed between bLf-lysate and gentamicin against 1 strain of E coli (strain 9062); synergistic bactericidal activity was found between bLf-lysate and rifampicin against all 3 strains of E coli. Moreover, partial synergy was observed between bLf-lysate and kanamycin, gentamicin, cephalothin, or cefamandole against the strains of E coli, but this partial synergistic activity was mostly seen against only 1 of the strains. Little interaction between bLf-lysate and tetracycline, ampicillin, penicillin G, or erythromycin was observed against the clinical strains of E coli. CONCLUSIONS AND CLINICAL RELEVANCE: A combination of bLf-lysate and certain antimicrobials may prove clinically effective against antimicrobial-resistant strains of E coli. 相似文献
12.
Bujnakova D Kmet V 《Journal of veterinary medicine. B, Infectious diseases and veterinary public health》2002,49(3):152-154
The effect of selected autoaggregative lactobacilli on enterohemorragic O157 Escherichia coli was studied. A total of 27 Lactobacillus sp. strains were examined for expression of autoaggregation and cell surface hydrophobicity. Autoaggregative isolates were obtained from the crops of chickens and vaginas of calves. Aggregative activity was seen between eight autoaggregative lactobacilli and six strains of enterohemorrhagic E. coli O157. The presence of aggregation-promoting factor (apf gene) was confirmed by polymerase chain reaction (PCR). We propose that autoaggregative lactobacilli that aggregate with enterohemorrhagic E. coli can express a class of APF proteins that exhibit the function of an aggregative mediator. The results of this study suggest that APF-producing lactobacilli could represent a further mechanism in the interaction of comensal microflora with enterohemorrhagic E. coli. 相似文献
13.
Turkey macrophage and heterophil bactericidal activity against Pasteurella multocida. 总被引：2，自引：0，他引：2
Bactericidal activity of turkey macrophages and heterophils was demonstrated in an in vitro colorimetric bactericidal assay. Two vaccine strains and one field isolate of Pasteurella multocida A:3,4 and a single isolate each of Escherichia coli and Staphylococcus aureus were compared for susceptibility to the bactericidal activity of turkey macrophages and heterophils. Only P. multocida A:3,4-strain M-9 (the least virulent strain) was susceptible to macrophage bactericidal activity in the absence of specific immune serum, whereas all three P. multocida A:3,4 organisms were killed when opsonized with specific immune serum. E. coli was susceptible to the bactericidal activity of macrophages, and S. aureus was resistant. All bacteria tested were highly sensitive to the bactericidal activity of intact turkey heterophils, regardless of the opsonin treatment. Electron microscopic findings suggested that heterophils may kill extracellular P. multocida. Only S. aureus and E. coli were killed by lysed heterophils. 相似文献
14.
The effects of pH, acetate, propionate, or butyrate concentration, and diet on acid resistance of fecal Escherichia coli and E. coli O157:H7 were determined by in vitro and in vivo experiments. The pH tested was from 4.0 to 8.0, and the VFA concentrations tested were 0 to 100 mM. The E. coli O157:H7 used was strain 505B. In an in vivo study, cattle were fed a grain-based diet, then either not switched or switched to a grain-based diet with 3% added calcium carbonate or two fiber-based diets (soybean hulls or hay). Acid resistance was expressed as viability after acid-shock at pH 2.0 for 1 h and 4 h for fecal E. coli and E. coli O157:H7, respectively. Enumeration methods used were multitube fermentation, agar plate, and petri-film methods. The E. coli O157:H7 was not found in continuous culture inocula or in vivo samples. The viability of fecal E. coli decreased linearly (P < 0.01) as the culture pH increased, and viability of E. coli O157:H7 was highest (P < 0.01) when cultivated at pH 6.0. The viability of fecal E. coli and E. coli O157:H7 showed quadratic responses (P < 0.05) as acetate and butyrate concentrations increased at pH 7.2, with maximal acid resistance at 20 and 12 mM, respectively. As propionate concentration increased, the acid resistance was not different (P > 0.05) for fecal E. coli. Acid resistance of E. coli was induced by acetate and butyrate, even though the environmental pH was near neutral. Similar results were measured in the in vivo study, where viability after acid shock was more dependent on VFA concentration than on pH. Increasing the dietary calcium carbonate concentration also increased (P < 0.05) acid resistance of fecal E. coli. Results from these studies demonstrated that culture pH and VFA affect acid resistance of E. coli. 相似文献
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16.
为研究从酸马奶中提取的植物乳杆菌DSM20174细菌素的理化特性,本试验提纯植物乳杆菌DSM20174细菌素,经过硫酸铵沉淀、透析后得到细菌素粗提液,再利用SephadexG-100凝胶柱层析进行纯化后,细菌素的比活力明显增加,达到154.70 AU/mL,得率为43.5%.采用牛津杯法测定纯化的植物乳杆菌DSM20174细菌素在3种不同方式处理下对牛源野生致病性大肠杆菌O78抑菌效果的影响.结果显示:①植物乳杆菌DSM20174细菌素在5组温度处理下,随着温度的升高抑菌作用降低,各组抑菌作用差异显著(P<0.05).即使121 ℃处理30 min后,抑菌直径仍达14.90 mm.②植物乳杆菌DSM20174细菌素在pH 2.0~12.0由低到高的11组酸碱处理下,pH越大抑菌直径越小,且除了pH 9.0和pH 10.0之间差异不显著(P>0.05)外,其余各组抑菌作用均差异显著(P<0.05). ③植物乳杆菌DSM20174细菌素经胰蛋白酶、胃蛋白酶、木瓜蛋白酶3种酶处理后抑菌直径变化明显,处理前后抑菌作用均差异显著(P<0.05).结果表明植物乳杆菌DSM20174细菌素是较好的抑菌活性物质,但不是热稳定性物质;具有较广泛的pH适用范围,且pH越小时其抑菌活性越强,在最适生长pH时抑菌活性有所增强;不是蛋白酶稳定性物质. 相似文献
17.
JIANG Jing Ao-ri-ge-le WANG Chun-jie ZHANG Yan ZHAO Chen-he WU Hong-jun HAO Jian-gang 《中国畜牧兽医》2016,43(2):444-449
To study the physicochemical properties extracted from koumiss of Lactobacillus plantarum DSM20174 bacteriocin,we purified the Lactobacillus plantarum DSM20174 bacteriocins and got the bacteriocin crude extractions after ammonium sulfate precipitation and dialysis.After purification with Sephadex G-100 gel column chromatography,bacteriocin specific activity apparently increased,reaching 154.70 AU/mL,yield was 43.5%.We detected the effects of purified Lactobacillus plantarum DSM20174 bacteriocin on bacteriostatic action of wild bovine pathogenic E.coli O78 by Oxford cup method under 3 different treatments.The results showed that:①In five groups of temperature treatments,the bacteriostatic action decreased with the increase of temperature,bacteriostatic actions of all groups were significantly different (P<0.05).Even after treatment at 121 ℃ 30 min,antimicrobial diameter was 14.90 mm.② After Lactobacillus plantarum DSM20174 bacteriocin were treated with pH 2.0 to pH 12.0,the higher of pH,the smaller of antibacterial diameter.The inhibitory effect of groups were significantly different (P<0.05) except pH 9.0 and pH 10.0.③Lactobacillus plantarum DSM20174 bacteriocins were treated by trypsin,pepsin and papain,antibacterial diameter apparently changed,bacteriostatic action was significantly different (P<0.05) before and after treatment.The results suggested that Lactobacillus plantarum DSM20174 bacteriocins were better antibacterial substances,but not thermal stability substances.It had a relatively wide pH range,and the smaller of pH,the stronger of its antibacterial activity,the antibacterial activity had been enhanced at optimum growth pH.It was not protease stability substances. 相似文献
18.
Pasteurella multocida exhibits nonspecific susceptibility to nonpolar antimicrobial agents such as triclosan, despite possessing an ultrastructurally typical gram-negative cell envelope. Capsulated and noncapsulated cell surface variants were examined to investigate the role outer membrane permeability plays in triclosan susceptibility. Test strains were unable to initiate growth in the presence of bile salts and were susceptible to triclosan with minimal inhibitory concentrations (MICs) ranging from 0.06 to 0.25 microg/ml. Disk agar diffusion bioassays revealed triclosan susceptibility to be dose dependent and all strains were susceptible to the hydrophobic antibiotics novobiocin, rifamycin SV, and chloramphenicol. Triclosan minimal bactericidal concentrations were greater than MICs, thereby suggesting that dose dependency reflected both bacteriostatic and bactericidal effects. Total and viable cell density growth kinetic determinations revealed a triclosan concentration of 2.0 microg/ml resulted in loss of batch culture viability within 4-24 h. Concentrations of 0.02 and 0.2 microg/ml exerted either a bacteriostatic or bactericidal effect depending on the strain. Uptake of the hydrophobic probe 1-N-phenylnaphthylamine was greater in P. multocida strains than refractory control organisms Pseudomonas aeruginosa and Escherichia coli thereby suggesting the presence of phospholipid bilayer regions in the outer membrane. Because triclosan inhibits a conserved enoyl-ACP reductase necessary for bacterial fatty acid biosynthesis, these data support the notion that extreme susceptibility in P. multocida is due to the general inability of the outer membrane to exclude nonpolar compounds. Moreover, susceptibility is independent of the presence of capsular material and the biocide is bactericidal in a concentration dependent manner. 相似文献
19.
The role of turkey complement in a serum bactericidal reaction was determined using serum-sensitive and serum-resistant Escherichia coli isolated from turkeys. Inactivation of complement by heating serum (56 C for 40 minutes) or by treating serum with 10 mM EDTA eliminated bactericidal activity. Serum-sensitive E coli organisms were killed by turkey serum treated with 10 mM ethylene glycol-bis-beta-(aminoethyl ether)-N,N,N',N'-tetraacetic acid and 5 mM MgCl2. Exposure of normal turkey serum to serum-sensitive or serum-resistant E coli resulted in equivalent reductions in hemolytic activity of serum. Treatment of serum-resistant E coli with antibody rendered the bacteria sensitive to bactericidal effects of normal turkey serum. Serum-sensitive E coli organisms were readily killed by an alternative complement pathway, serum-sensitive and serum-resistant E coli activated the complement system equally well, and antibody was required for complement-mediated killing of certain serum-resistant E coli organisms from turkeys. 相似文献
20.
16味蒙药对金黄色葡萄球菌和大肠杆菌O8的体外抑菌效果研究 总被引：1，自引：1，他引：0
为筛选对奶牛乳房炎主要致病菌金黄色葡萄球菌（S.aureus）和大肠杆菌O8（E.coli O8）具有良好抑菌作用的蒙药,本试验采用牛津杯法测定金银花、黄连、何首乌、地榆、五味子、秦皮、穿心莲、甘草、蒲公英、夏枯草、虎杖、柴胡、黄柏、苦参、石榴皮、板蓝根16味蒙药的抑菌圈直径,微量稀释法和平板法测定蒙药的最小抑菌浓度（minimal inhibitory concentration,MIC）和最小杀菌浓度（minimal bactericidal concentration,MBC）,棋盘法测定敏感蒙药对E.coli O8和S.aureus的协同指数（fractional inhibitory concentration index,FICI）。结果显示,黄柏、金银花、黄连、五味子、蒲公英、秦皮6味蒙药对S.aureus的抑菌圈直径为10.22~22.44 mm,MIC为15.6~250 mg/mL;五味子、金银花、黄连、秦皮4味蒙药对E.coli O8的抑菌圈直径为11.29~26.41 mm,MIC为15.6~500 mg/mL;黄柏与黄连联合用药对S.aureus的FICI为0.36,为协同作用,黄连与地榆联合用药对E.coli O8的FICI为0.48,为协同作用。综上所述,金银花、黄连、五味子、秦皮、蒲公英、黄柏6味蒙药对S.aureus综合抑菌效果达极敏或高敏;金银花、黄连、五味子、秦皮4味蒙药对E.coli O8综合抑菌效果达极敏或高敏,黄柏、黄连、秦皮在抑制S.aureus的组方中可优先考虑,黄连与地榆在抑制E.coli O8的组方中可优先考虑。 相似文献