不同微生物诱导家蝇幼虫表达抗菌肽的特性

研究不同微生物诱导家蝇幼虫表达的抗菌肽特性.用3种不同的病源菌通过针刺感染的方法诱导家蝇幼虫表达抗菌肽,通过Sephadex G25分离,用Hult mark改进法和抑菌圈测定法作抑菌试验,用毛细管电泳（CE）分析不同微生物诱导得到的抗菌肽样品差异,检测抗菌肽的热稳定性和酸碱耐受性.发现不同微生物诱导产生的家蝇抗菌肽具有广谱抑菌性,但不同样品对不同病源菌抑菌活性有差异,不同测定抑菌效果的方法对抑菌结果有影响,各种抗菌肽样品CE蛋白谱具有明显不同.抗菌肽样品都具有热稳定性和酸碱耐受性.说明不同微生物诱导产生的家蝇抗菌肽类型以及抗菌肽含量与诱导源有关,抗菌肽为家蝇幼虫体内固有成分,诱导增加了抗菌肽的表达量同时刺激新抗菌肽的产生.用志贺氏菌、金黄色葡萄球菌、鼠伤寒沙门氏菌诱导家蝇幼虫可产生较多含量高活性好的抗菌肽.     

纳米光触媒抗菌织物的研究与开发

介绍了纳米光触媒抗菌织物的杀菌机理及其整理工艺,利用光触媒光催化活性的技术优势开发的光触媒抗菌织物,并在实验室条件下,对其抗菌性能进行了研究和评价.结果表明,光触媒抗菌织物对革兰氏阴性菌大肠杆菌(E.coli)、革兰氏阳性菌金黄色葡萄菌(S.aureus)和真菌白色念珠菌(C.albicans)均有较强的抑制和杀灭作用,证明了纳米光触媒织物具有很好的广谱抗菌性能.     

家蝇幼虫培养及其抗菌肽的初步研究

通过天然家蝇幼虫的人工培养及Tricine-SDS-PAGE电泳,分离纯化出2种抗菌肽（命名为MDL-1、MDL-2）,并检测了该抗菌肽的抑菌活性.MDL-1的相对分子量10772Da,MDL-2的相对分子量6091Da.实验结果表明：剩肉菜（骨头和虾皮等）对天然家蝇的产卵引诱力最大;红糖和奶粉的最佳比例为3：1;家蝇幼虫食料最佳含水量为80%;家蝇幼虫单体平均增重最大的最佳培养基为麦麸和骨头的混合物.抑菌活性检测结果：MDL-1对枯草芽胞杆菌的抑菌效果最强,大肠杆菌次之,金黄色葡萄球菌最差;MDL-2对大肠杆菌的抗菌效果最好,金黄色葡萄球菌次之,枯草芽胞杆菌稍差.     

产类细菌素乳酸菌的筛选及其生物学特性研究

采用平板稀释和CO2厌氧培养技术,从多种发酵食品中分离出158株乳酸菌。通过牛津杯双层平板扩散试验,筛选出1株有明显抑菌活性的乳酸菌R-6,经初步鉴定为乳酸乳杆菌(Lactobacillus sp.)。R-6发酵上清液用NaOH调节pH5.5,对指示菌Escherichi coli.仍有明显抑菌活性,过氧化氢酶作用后其抑菌效果基本不变,因此可以排除乳酸和过氧化氢的干扰;R-6培养液经胰蛋白酶和蛋白酶K处理后,抑菌活性明显降低,且超过100℃热处理其抑菌活性迅速丧失,证实所产抑菌物质确系多肽类细菌素。该细菌素在酸性条件下活性较强,对革兰氏阴性菌(E.coli)抑菌作用较强,对革兰氏阳性菌(Bacillus subtilis和Staphlococcus aureus)也有明显抑制,显示出一定的抗菌广谱性。     

杂合抗菌肽NK-LPd的设计、表达及抑菌活性评价

目的：了解杂合抗菌肽NK-LPd的抑菌活性，探讨进一步开发潜力。方法：用两个甘氨酸作接头连接NK-lysin和Piscidin的活性片段，生物信息学技术预测杂合抗菌肽的理化性质和功能结构，根据毕赤酵母（Pichia pastoris）的密码子偏好性优化杂合抗菌肽NK-LPd基因序列，重叠延伸聚合酶链式反应（gene splicing by overlap extension polymerase chain reaction,SOE-PCR）扩增基因并与分泌型表达载体pPIC9K连接，通过化学法将其转化至毕赤酵母KM71感受态细胞中，经0.5%甲醇诱导表达和亲和纯化后获得杂合抗菌肽NK-LPd，评价其抗菌活性。结果：成功构建了KM71/pPIC9K-NK-LPd，经诱导表达5 d后上清液中获得了相对分子质量约6 kDa的表达产物，与预期大小相符；抗菌活性实验表明，NK-LPd对革兰氏阴性菌和革兰氏阳性菌均具有较强的抑菌活性，与母体肽相比，杂合抗菌肽NK-LPd的抑菌活性显著增强。结论：设计并在毕赤酵母KM71中分泌表达了杂合抗菌肽NK-LPd，其抑菌活性优于母体肽。本研究可为新型杂合抗...     

普洱茶不同提取物体外抑菌活性研究

研究了不同溶剂普洱茶提取物及萃取物的体外抑菌活性。论文采用滤纸片扩散法和最低抑菌浓度检测了水提、75%和95%乙醇普洱茶提取物对S.aureus、E.coli、P.aeruginosa及B.subtilis体外抑菌效果。同时分析了95%醇提物的不同溶剂萃取物对供试菌的影响。结果表明:95%乙醇浸提物抑菌效果最好,尤其对S.aureus、E.coli最为明显,抑菌圈分别为19.58±0.24 mm、14.58±0.24 mm,MIC分别为0.63 mg/mL,0.39 mg/mL,但对B.subtilis抑菌效果差。在95%醇提物的不同溶剂萃取物中,萃取物抑菌活性为:乙酸乙酯>正丁醇>石油醚>氯仿。乙酸乙酯萃取物对S.aureus抑制效果最好,其抑菌圈直径为31.88±0.24 mm,MIC为0.47 mg/mL。普洱茶提取物的醇提乙酸乙酯萃取提物能显著抑制革兰氏阴性菌和阳性菌的生长,研究结果为普洱茶抗菌活性成分的开发利用提供一定的实践和数据参考。     

苦瓜溶菌酶的分离纯化及特性研究

目的:分离纯化苦瓜溶菌酶,同时进行酶学性质及其生物学性质研究,为苦瓜生物活性蛋白的研究提供依据.方法:应用盐提法、离子交换层析法(阴离子色谱柱Source Q和阳离子色谱柱POROS 50HS)、反相毛细管色谱和SDS-PAGE等方法分离纯化和鉴定.结果:分离纯化得到的溶菌酶经鉴定达到电泳纯,分子质量为20.1 kDa,酶比活力2000 U/mg,纯化倍数164.6;抗菌试验表明,苦瓜溶菌酶对总状毛霉(M ucor racem osus)、稻纹枯病菌(osusRhizocwnia solani)、大肠杆菌(Escherichia coli)具有较强的抑制作用,对大肠杆菌完全抑制的最低浓度为0.59 μmol/L,而对金黄色葡萄球菌(S taphy lococcus aureus)的抑制活性不明显.结论:分离表征到一种具有抗菌活性的新型植物溶菌酶,使用离子交换层析柱高效可行.     

2株中国红豆杉内生细菌代谢产抑菌活性物质的研究

自秦巴山区野生中国红豆杉(Taxus chinensis)中分离的25株内生细菌中筛选出2株具有较广抑菌活性的菌株TC-3和TC-2,通过生物学特征研究和16S rDNA序列分析,初步鉴定为Bacillus sp.和Bacillus subtilis.在排除酸性产物和过氧化氢的干扰后,TC-3和TC-2菌株发酵上清液对金黄色葡萄球菌(Staphyloccocus aureus)、枯草芽孢杆菌(Bacillus subtilis)等革兰氏阳性菌和大肠杆菌(Escherichia coli)等革兰氏阴性菌具有较好的抑菌作用,而且对部分真菌也有抑菌作用;经胰蛋白酶、胃蛋白酶和蛋白酶K处理后发酵液抑菌活性略有下降,表明该活性物质为非蛋白成分,或起抑菌作用的非单一物质.该活性物质不同于一般细菌素,属于类细菌素.它具有很好的热稳定性,在酸性条件下稳定且活性高,对蛋白酶敏感性低,且具有较广的抗菌谱.     

蚕蛹抗菌肽的分离纯化及其理化性质的研究

本研究采用加热-层析法和葡聚糖凝胶层析法分离纯化蚕蛹抗菌肽,利用Tricine SDS-PAGE电泳法确定抗菌肽的相对分子质量;采用琼脂孔穴扩散法研究不同条件对蚕蛹抗菌肽活性的影响。研究结果表明:蚕蛹抗菌肽的相对分子质量为4.85kD。纯化后的蚕蛹抗菌肽在100℃处理20min对大肠杆菌的抑菌圈直径可达1.80cm;pH在7.0-7.5时抑菌圈平均直径为1.975cm;室温放置3h抑菌圈直径可达2.05cm;盐离子浓度在0.2mol/L时抑菌活性最好抑菌圈直径为2.02cm。     

产类细菌素乳酸菌的筛选及其生物学特性研究

采用平板稀释和CO2厌氧培养技术,从多种发酵食品中分离出158株乳酸菌.通过牛津杯双层平板扩散试验,筛选出1株有明显抑菌活性的乳酸菌R-6,经初步鉴定为乳酸乳杆菌(Lactobacillus sp.).R-6发酵上清液用NaoH调节pH5.5,对指示菌Escherichi coil.仍有明显抑菌活性,过氧化氢酶作用后其抑菌效果基本不变,因此可以排除乳酸和过氧化氢的干扰;R-6培养液经胰蛋白酶和蛋白酶K处理后,抑菌活性明显降低,且超过100℃热处理其抑菌活性迅速丧失,证实所产抑菌物质确系多肽类细菌素.该细菌素在酸性条件下活性较强,对革兰氏阴性菌(E.coil)抑菌作用较强,对革兰氏阳性菌(Bacillus subfilis 和 Staphlococcus aureus)也有明显抑制,显示出一定的抗菌广谱性.     

The in vitro antibacterial activity of dietary spice and medicinal herb extracts

The in vitro antibacterial activities of a total of 46 extracts from dietary spices and medicinal herbs were investigated by agar-well diffusion method against five foodborne bacteria (Bacillus cereus, Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, and Salmonella anatum). Their total phenolic contents were also evaluated. Many herb and spice extracts contained high levels of phenolics and exhibited antibacterial activity against foodborne pathogens. Gram-positive bacteria were generally more sensitive to the tested extracts than Gram-negative ones. S. aureus was the most sensitive, while E. coli was the most resistant. There were highly positive relationships (R(2)=0.73-0.93) between antibacterial activities and phenolic content of the tested extracts against each bacterium. This suggested that the antibacterial activity of the tested extracts was closely associated with their phenolic constituents.     

Isolation and characterisation of antibacterial peptides derived from the f(164–207) region of bovine αS2-casein

A chymosin digest of sodium caseinate, which showed antibacterial activity against Listeria innocua, was fractionated using reverse phase high performance liquid chromatography and the purified antibacterial peptides were characterised by mass spectrometry, N-terminal amino acid sequencing and comparison to peptide masses of theoretical enzymic digests of milk proteins. Five antibacterial peptides, Cr1, Cr3, Cr4, Cr5 and Cr7 corresponding to amino acid residues 181–207, 180–207, 175–207, 164–207 and 172–207 of bovine α_S2-casein, respectively, were isolated. The minimal inhibitory concentration of peptides Cr1, Cr4 and Cr5 was determined against a range of Gram-positive and Gram-negative bacteria and showed similar activities to those of the bacteriocin peptide, nisin and the antibacterial peptide, lactoferricin B against certain Gram-positive bacteria. A partially purified chymosin digest of sodium caseinate (Cr_MIX) was prepared and observed to be heat stable for up to 15 min on exposure to 121 °C. Although Cr_MIX showed bactericidal activity against Salmonella Typhimurium in 0.1% (w/v) peptone medium, no antibacterial activity was observed when tested in skim milk at the same concentration.     

溶菌酶功能化金纳米颗粒抑菌性能研究

为了提高溶菌酶的稳定性及对革兰氏阴性菌的抑菌性能,以金纳米颗粒为核,通过表面定向修饰溶菌酶,制备了绿色、高效的溶菌酶功能化金纳米颗粒抑菌材料,研究溶菌酶与金纳米的比例、纳米颗粒质量浓度等对抑菌效果的影响,研究溶菌酶功能化纳米材料对大肠杆菌的抑菌机理及对人神经母细胞瘤(SH-SY5Y)的细胞毒性。结果表明:与未修饰的金纳米及单纯的溶菌酶相比,溶菌酶功能化金纳米颗粒对大肠杆菌和金黄色葡萄球菌的抑菌效果均显著增强,表现出协同抑菌作用,在最优条件下,0.1 g/L溶菌酶功能化金纳米颗粒可以完全杀死2种细菌,并且该溶菌酶功能化金纳米颗粒具有持久抑菌性及良好的生物相容性,对哺乳细胞没有毒性。透射电子显微镜和活菌/死菌荧光染色结果表明:溶菌酶功能化金纳米颗粒主要通过破坏菌体细胞壁和细胞膜结构,从而杀死细菌。     

桦褐孔菌多酚抑菌活性分析研究

为减少辅料糠壳给酒体带来的邪杂味，研究箭竹作为辅料酿造小曲酒的工艺。分别考察箭竹的粉碎大小、加量、小曲种类、入窖温度对箭竹小曲酒的影响。结果表明，约7.0 mm长、3.0 mm宽的箭竹适合作小曲固态酿酒辅料，箭竹使用前清蒸1 h，加量为7%，选用泸州某小曲，入窖温度为24 ℃。通过理化分析及感官评定表明在该优化条件下，出酒率为47%以上，总酸含量为685.3 mg/L，总酯含量为1 071.5 mg/L，达到优级白酒标准；小曲酒酒体清香纯正，柔和谐调、醇甜爽净，除具有乙酸乙酯为主体的复合香气外，还带有箭竹独有的清香味。     

林蛙抗菌肽的制备及抑菌活性研究

目的超声波方法提取林蛙表皮多肽,对其氨基酸组成和抑菌活性进行分析。方法以p H 4.5醋酸-醋酸钠缓冲液为提取溶剂,超声波方法提取林蛙表皮多肽,超高效液相色谱(UPLC)方法分析其氨基酸组成,同时采用活菌计数和滤纸片方法测定其抑菌活性。结果超声波方法提取林蛙多肽,提取率为19.81%,多肽分子量在3000~5000 Da,该活性多肽作用2 min对大肠杆菌、金黄色葡萄球菌、白色念珠菌、铜绿假单胞菌抑菌率均可达85%以上,作用5 min抑菌率可达100%;其对4株菌抑菌圈直径均可达10 mm以上。结论采用超声波方法可以从中国林蛙皮中提取抗菌肽物质,该抗菌肽为碱性多肽,对革兰氏阳性菌、革兰氏阴性菌均具有很强的抑菌活性。     

凝结芽孢杆菌XZQ-16抗菌脂肽分离鉴定及抗菌特性

对凝结芽孢杆菌(Bacillus coagulans)XZQ-16脂肽分离鉴定并探讨其抗腐败菌特性.通过酸沉、硅胶柱层析和Sephadex LH-20层析对脂肽分离纯化,利用傅里叶红外光谱(FT-IR)和反相高效液相色谱(RP-HPLC)对脂肽分析鉴定.结果表明,硅胶柱层析得到三个流分具有明显抗菌活性;Sephadex...     

小菜蛾moricin在毕赤酵母中的表达及抑菌活性分析

抗生素的过度使用给自然生态带来诸多不利影响,寻找合适的抗生素的替代物,从而减少抗生素的使用正成为当下的研究热点。以来自于小菜蛾的特异性抗菌肽moricin为研究对象,研究其酵母异源表达水平和抑菌性能及生化特性,为进一步的开发利用提供理论支持。根据已有的小菜蛾抗菌肽moricin特异性基因信息,采用聚合酶链式反应扩增其成熟肽基因mor-3,并克隆至pGAPZαA质粒中,构建组成型分泌表达载体pGAPZαA-mor3,线性化片段电转化导入毕赤酵母SMD1168菌株,高质量浓度Zeocin筛选获得高拷贝重组转化子。以YPD为培养基进行摇瓶发酵,重组蛋白获得高效表达,分子质量约为5kD,与理论预测的基本一致;发酵60 h,上清液中重组蛋白表达量达248.98 mg/L,而且耐热性能良好,同时具备较强的耐强酸及强碱的能力,特别在强酸环境中活性保持稳定,体现了较好的机体内环境的适应性潜力;对部分革兰氏阴性菌和革兰氏阳性菌均具有抑菌作用,特别是对革兰氏阴性菌具备特异性较强的抑制作用,对大肠杆菌的最低抑菌浓度为6.25μg/mL,而对金黄色葡萄球菌的最低抑菌浓度仅为124.49μg/mL。独特的抑菌性能和理化特点,使其具备广阔的开发应用前景及良好的社会与环保效益。     

Evaluation of antibacterial activity of 3-butenyl, 4-pentenyl, 2-phenylethyl, and benzyl isothiocyanate in Brassica vegetables

This study investigated antibacterial activities of 4 isothiocyanates (3-butenyl, 4-phentenyl, 2-phenylethyl, and benzyl isothiocyanate) against 4 Gram-positive bacteria (Bacillus cereus, Bacillus subtilis, Listeria monocytogenes, and Staphylococcus aureus) and 7 Gram-negative bacteria (Aeromonas hydrophila, Pseudomonas aeruginosa, Salmonella choleaesuis, Salmonella enterica, Serratia marcescens, Shigella sonnei, and Vibrio parahaemolyticus) by an agar disc diffusion assay. Benzyl isothiocyanate (> 90.00 mm inhibition zone diameter at 0.1 μL/mL) and 2-phenylethyl isothiocyanate (58.33 mm at 0.2 μL/mL) showed large inhibition zones especially against B. cereus. Also, 3-butenyl isothiocyanate (21.67 mm at 1.0 μL/mL) and 4-pentenyl isothiocyanate (19.67 mm at 1.0 μL/mL) displayed potent antibacterial activity against A. hydrophila. Benzyl and 2-phenylethyl isothiocyanate indicated higher activity against most of the pathogenic bacteria than 3-butenyl and 4-pentenyl isothiocyanate, and were more effective against Gram-positive bacteria than Gram-negative bacteria.     

Potent antibacterial peptides generated by pepsin digestion of bovine lactoferrin.

The antibacterial properties of enzymatic hydrolysates of bovine lactoferrin were examined to determine whether active peptides are produced from this protein. Hydrolysates prepared by cleavage of lactoferrin with porcine pepsin, cod pepsin, or acid protease from Penicillium duponti showed strong activity against Escherichia coli O111, whereas hydrolysates produced by trypsin, papain, or other neutral proteases were much less active. Low molecular weight peptides generated by porcine pepsin cleavage of lactoferrin showed broad-spectrum antibacterial activity, inhibiting the growth of a number of Gram-negative and Gram-positive species, including strains that were resistant to native lactoferrin. The antibacterial potency of the hydrolysate was at least eightfold greater than that of undigested lactoferrin with all strains tested. The active peptides retained their activity in the presence of added iron, unlike native lactoferrin. The effect of the hydrolysate was bactericidal as indicated by a rapid loss of viability of E. coli O111. The lactoferrin hydrolysate described in the present study has commercial value as a natural preservative agent for use in foods and cosmetics, and as a functional component of new clinical foods for prevention or treatment of gastrointestinal disease.