致病杆菌和发光杆菌抗菌代谢产物研究进展

致病杆菌Xenorhabdus和发光杆菌Photorhabdus是昆虫病原线虫肠道共生细菌,具有对宿主昆虫致病和对寄主线虫共生的双重特性,是一类特殊的生防细菌资源,其代谢产物具有广泛的杀虫和抑菌功能。本文综述了近年来昆虫病原线虫共生细菌产生的抗菌物质、编码抗菌代谢产物的基因及抗菌机制的研究进展。     

尿素-SDS-PAGE显示干酪成熟过程中酪蛋白降解生成的小分子多肽

本文采用尿素－SDS－PAGE对多肽标准品MarkerI(2512-16949）的分子量进行了测定，并对干酪成熟过程中酪蛋白降解生成的小分子多肽进行了分析。结果表明，采用16％T，6C物分离胶，6％T，3％C的浓缩胶，6 mol/L的尿素分析系统能清楚地显示分子量为2512－16949的小分子多肽，多肽标准品的直线回归系数R^2=0.9948，样品在固定，染色和脱以过程中不易扩散丢失，不需特殊染色方法，该法是显示小分子多肽物质的简单，快速，有效的方法。对成熟30天的霉菌干酪样品进行分析结果表明，样品中的酪蛋白降解后生成了大量的小分子多肽物质（分子量＜100000Da).     

Epitope identification and <Emphasis Type="Italic">in silico</Emphasis> prediction of the specificity of antibodies binding to the coat proteins of <Emphasis Type="Italic">Potato Virus Y</Emphasis> strains

A phage library containing 2.7 × 10⁹ randomly expressed peptides was used to determine the epitopes of three monoclonal antibodies that bind to the coat protein of potato virus Y. Construction of the consensus sequences for the peptides obtained after three selection rounds indicated that each antibody recognized a different epitope located within the first 50 N-terminal amino acids of the coat protein. The location of the epitopes was confirmed by heterologous expression of the N-terminal part of the coat protein in Escherichia coli, and, subsequently, by performing an immunological test with the three antibodies. The accuracy of the phage library was demonstrated by predicting in silico the cross-reactivity of the three antibodies with other potyvirus family members. ELISA and in silico predictions revealed the same results in almost every case. The potential of peptide phage libraries to optimize the use of antibodies in plant virology is discussed.     

Acquired antimicrobial resistance in the intestinal microbiota of diverse cat populations

The aim of this study was to investigate the prevalence of acquired antimicrobial resistance in the resident intestinal microbiota of cats and to identify significant differences between various cat populations. Escherichia coli, Enterococcus faecalis, E. faecium and Streptococcus canis were isolated as faecal indicator bacteria from rectal swabs of 47 individually owned cats, 47 cattery cats and 18 hospitalised cats, and submitted through antimicrobial sensitivity tests. The results revealed that bacteria isolated from hospitalised and/or cattery cats were more frequently resistant than those from individually owned cats. E. coli isolates from hospitalised cats were particularly resistant to ampicillin, tetracycline and sulfonamide. Both enterococci and streptococci showed high resistance to tetracycline and in somewhat lesser extent to erythromycin and tylosin. Most E. faecium isolates were resistant to lincomycin and penicillin. One E. faecalis as well as one E. faecium isolate from hospitalised cats showed 'high-level resistance' (MIC > 500 microg/ml) against gentamicin, a commonly used antimicrobial agent in case of human enterococcal infections. The results of this research demonstrate that the extent of acquired antimicrobial resistance in the intestinal microbiota of cats depends on the social environment of the investigated population. It is obvious that the flora of healthy cats may act as a reservoir of resistance genes.     

象拔蚌酶解制备抗氧化肽的工艺研究

[目的]探讨酶解象拔蚌蛤肉制备抗氧化肽的最佳工艺条件。[方法]采用复合蛋白酶对象拔蚌蛤肉进行酶解获得抗氧化肽,以羟自由基清除率及蛋白水解度为指标,通过单因素试验与响应面分析法对酶解工艺条件进行优化。[结果]象拔蚌蛤肉的最佳酶解工艺条件为料水比1∶11.11,加酶量3 000 U/g,酶解时间1.2 h,酶解温度55℃,pH 7.52;在该条件下,酶解液获得较高的蛋白水解度,同时对羟基自由基和DPPH自由基显示出很好的清除效果,其EC50值分别为11.26和37.75 mg/ml。[结论]该研究为象拔蚌保健食品的开发提供了依据。     

鸡白痢沙门氏菌临床分离株的耐药性分析

旨在了解鸡白痢沙门氏菌临床分离株的耐药性情况。对疑似雏鸡白痢的33份病料进行病原菌的分离鉴定、形态学观察和生化试验,鉴定出26株鸡白痢沙门氏菌。采用Kindy-Bauer法检测分离菌株对14种抗菌药敏感性。试验结果表明,分离菌株对庆大霉素、阿米卡星、新霉素、多粘菌素B、复方新诺明和氯霉素较为敏感,耐药率分别为11.54%、0、7.69%、0、19.23%和15.38%;对阿莫西林、氨苄西林、链霉素、四环素、多西环素、恩诺沙星、诺氟沙星和环丙沙星耐药性较强,耐药率分别为53.85%、65.38%、57.69%、100%、69.23%、61.54%、76.92%和53.85%。且所有鸡白痢沙门氏菌分离株均为多重耐药性,其中以6耐和7耐的菌株为主,分别占42.31%和30.77%。鸡白痢沙门氏菌分离株对多数抗菌药物具有不同程度的耐药性,加强对临床分离株的耐药监测,对于指导临床合理用药及控制疾病流行具有重要的现实意义。     

天竺葵提取物对黄瓜病菌的抑制作用

采用天竺葵(Pelargonium hortorum)叶片提取物对黄瓜的镰刀菌(Fusarium oxyporum)、链格孢菌(Alternaria cucumerina)、蔓枯病菌(Ascochyta citrullina)进行抑菌实验.结果表明,天竺葵提取物对3种黄瓜病菌的菌丝生长均有一定的抑制作用,且抑制效果与提取物浓度呈正相关,提取物对蔓枯菌菌丝生长的抑制作用最强,对镰刀菌菌丝生长的抑制作用次之,对链格孢菌菌丝生长的抑制效果最弱.     

鱼腥草甲醇提取物体外抗氧化性及抑菌活性评价

采用α-脱氧核糖法、邻苯三酚自氧化法、1,1-二苯基-2-三硝基苯肼(DPPH)法体外测定了鄂西北产鱼腥草甲醇提取物的抗氧化性,同时采用生长速率法和孢子萌发法评价了其对绿色木霉、啤酒酵母菌、黑曲霉、木质层孔菌及枯草芽孢杆菌等微生物的抑制作用。结果表明:鱼腥草甲醇提取物具有一定抗氧化性和抑菌活性,在试验浓度范围内,抗氧化活性及抑菌活性与其质量浓度呈量效关系。     

玫瑰露抑菌效果研究

研究了玫瑰露对4种细菌(沙门氏菌、大肠杆菌、枯草芽孢杆菌和苏云金杆菌)、3种霉菌(木霉、青霉、黑曲霉)以及2种酵母菌(啤酒酵母、葡萄酒酵母)的抑菌活性和最低抑菌浓度(MIC),采用滤纸片法测定抑菌圈、液体培养法测定最低抑菌浓度。结果表明,玫瑰露对供试细菌,不论是G+菌还是G-菌,都有较强的抑菌活性,而对霉菌、酵母菌的抑菌活性不明显;对细菌的抑菌效果以沙门氏菌最强,MIC为0.98 mL/L。说明玫瑰露既可以加入到食品中作为香料,同时可配合其他天然香料使用,组成复配防腐剂。     

生物活性多肽制备与纯化的研究进展

文中对生物活性多肽的制备和纯化进行了综述,详细阐述了生物活性肽的制备,包括化学合成法、提取法、重组菌生产法和酶解法,及其分离和纯化,包括凝胶过滤色谱、反相液相色谱等方法。