家蝇抗菌肽MDC对鼠伤寒沙门氏菌的抑菌稳定性研究

以鼠伤寒沙门氏菌(Salmonella typhimurium)作为研究对象,探讨家蝇抗菌肽(Musca domestica cecropin,MDC)在不同条件下的抑菌稳定性.采用牛津杯法研究pH值、温度、光照、蛋白酶、金属离子、表面活性剂及有机试剂对MDC抑菌活性(抑菌圈大小)的影响.在酸性条件下MDC的抑菌活性稍...     

青海湖M1菌发酵液体外抗菌活性及稳定性的初步研究

从青海湖中分离得到一株霉菌M1,采用平板抑菌法进行体外抗菌作用以及pH值、温度因素对其抗菌活性的影响。结果表明：该菌株发酵液对大肠杆菌、枯草芽孢杆菌及金黄色葡萄球菌都有明显的抑菌效果。M1菌株发酵液的抑菌活性对热稳定性较差,在pH值3～7的条件下抑菌效果最佳,遗传稳定性也不高。     

5种常见中草药的抑菌性研究

采用平板打孔法对五倍子、金银花、大青叶、穿心莲、蒲公英这5种常见中草药进行抑菌试验,并测定其MIC(最低抑菌浓度)及抑菌时间。研究结果表明:5种中草药提取液对Bacillussubtilis抑菌效果普遍较好,五倍子、金银花、大青叶对Escherichiacoli抑菌效果较好;五倍子提取液药效时间较长,而其他中草药抑菌时间较短。     

石榴果皮提取物抑菌活性研究

以12种常见的食品污染菌为供试菌,采用平板打孔法对10个品种石榴果皮的9种溶剂提取物进行抑菌效果研究,并对甲醇提取物的化学成分进行了初步分析。结果表明,甲醇提取物抑菌活性最强;石榴果皮提取物对供试菌种中的细菌的抑制效果最强,对革兰氏阳性菌的抑制效果强于对革兰氏阴性细菌的抑制效果,对酵母菌的抑制效果较弱,对霉菌几乎没有抑制作用。在供试的10个石榴品种中,‘峄城软籽’石榴果皮甲醇提取物的抑菌活性最高。化学成分系统预试结果表明,石榴果皮甲醇提取物中含有黄酮及其苷类物质、生物碱、酚类、鞣质类等成分。     

海洋活性芽胞杆菌MD-5发酵时间优化及抑菌性质研究

[目的]探究海洋活性芽孢杆菌MD-5抑菌活性及性质。[方法]采用测定抑菌半径结合OD_(600)及pH确定最佳发酵时间;通过平板琼脂扩散法、平板对峙法测定其抑菌谱;通过测量抑菌圈面积探究加热时间、pH对抑菌活性物质的影响。[结果]在既定培养条件下,该菌株产抑菌活性物质最优的发酵时间为34 h,对多种指示菌具有抑制作用;其发酵上清在100℃下加热2、5、10 min活性保留分别为88.9%、60.4%、38.9%,加热15 min完全失活;当pH 5.0～7.0活性基本不变,pH为酸性活性有所降低,为碱性活性下降明显,pH≥11完全失活。[结论]该菌株具有广谱的抑菌作用,可有效抑制革兰氏阳性菌和部分阴性菌及真菌;所产生的活性物质对温度及pH敏感,高温或碱性环境易于降解失活。     

半边莲总黄酮提取工艺及抑菌活性的研究

研究了乙醇浓度、料液比、提取温度、提取时间对半边莲中总黄酮提取率的影响,并通过正交实验优化了半边莲中总黄酮的提取工艺条件,结果表明:当乙醇浓度60%,料液比为1∶40(g/m L),提取温度60℃,提取时间2.5 h,从半边莲中提取总黄酮的得率为1.69%。考察了半边莲总黄酮提取物对几种常见微生物的抑菌作用,结果表明半边莲总黄酮提取物具有一定的抑菌活性,对革兰氏阴性菌的抑制作用大于革兰氏阳性菌,低浓度下对青霉菌和酵母菌抑制效果不明显。     

土茯苓提取物抗细菌活性的研究

通过测定土茯苓提取物对革兰氏阳性菌和革兰氏阴性菌的抑菌活性,来更全面的评价和综合利用土茯苓资源,实验结果表明土苓955乙醇和乙酸乙酯的提取物抑菌范围广,服抑菌活性强,这两种提取物的MIC和MBC值显示了土茯苓作为抗细菌资源的可利用价值。     

20种中药提取物对牙龈卟啉单胞菌抑制作用的体外研究

目的筛选评价20种中药提取物对牙龈卟啉单胞菌抑制作用。方法选择20种有较强抑菌作用及清热解毒作用的中药提取物,采用杯碟法进行体外抑菌试验,比较各中药对牙龈卟啉单胞菌的抑菌环直径和最低抑菌浓度(MIC)。结果水煎剂中黄连、乌梅、五味子、五倍子和黄芩的MIC为0.0488~1.5625mg/mL。油剂中丁香油、香薷油的MIC为0.3906~1.5625mg/mL。结论本实验选择的20种中药提取物中香薷油、黄连、乌梅、五味子、五倍子和黄芩的抑菌敏感度最高。     

100 种中草药水提物体外抑杀无乳链球菌的药效研究

无乳链球菌(Streptococcus agalactiate)对罗非鱼产业以及人类健康有重要威胁, 为了减少抗生素抑杀无乳链球菌用量, 试验了100 种中草药水提物体外抑杀罗非鱼无乳链球菌的药效。结果表明, 黄连、大黄、黄柏、乌梅、五倍子、防己、公丁香、天花粉、白头翁、鱼腥草和苏木水提药原液有明显抑菌效果, 但将这些中药水提药液的pH 值调至中性后, 大部分中草药抑菌效果显著下降 (p<0.01), 甚至消失, 仅黄连、公丁香、五倍子和防己药液在调节pH 值后还有显著抑菌效果。采用二倍梯度稀释法测定pH 值调至中性后仍有抑菌作用的4 种中草药的最低抑菌浓度(MIC)和最小杀菌浓度(MBC),发现黄连的MIC 和MBC 值分别为3.125 mg·mL–1 和6.250 mg·mL–1, 效果最好; 五倍子的MIC 和MBC值均为6.250 mg·mL–1, 效果其次; 防己的MIC 和MBC 值均为25.000 mg·mL–1; 公丁香的MIC 和MBC 分别为50.000 mg·mL–1和100.000 mg·mL–1。     

食品包装用箬叶提取物抑菌活性及稳定性研究

目的：以牛津杯法研究箬叶提取物的抑菌活性和稳定性。方法：用水超声法提取箬叶提取物，以枯草芽孢杆菌、铜绿假单胞菌、痢疾志贺氏菌和伤寒沙门氏菌为指示菌，总抑菌圈为考察指标，进行抑菌试验；用正交试验分析料液比、提取时间和提取次数3个因素不同水平对箬叶提取物抑菌效果的影响，优化提取工艺，测试提取物的最小抑菌浓度（MIC）和稳定性。结果：研究表明，在工艺参数料液比1∶14、超声4次和每次50 min条件下获得的提取物对4种指示菌的抑菌效果最显著，提取物对枯草芽孢杆菌、铜绿假单胞菌、痢疾志贺氏菌和伤寒沙门氏菌的最小抑菌浓度分别为0.025、0.05、0.025、0.05 g/mL，并且在pH=4和100℃条件下抑菌效果稳定。结论：箬叶水提取物对枯草芽孢杆菌、铜绿假单胞菌、痢疾志贺氏菌和伤寒沙门氏菌具有显著的抑菌效果，且热稳定性和酸稳定性良好。     

黑眶蟾蜍皮肤抗菌肽的制备及其性质

收集黑眶蟾蜍皮肤分泌物,经Sephadex G-25去除大分子蛋白后,利用微量测定法进行抗菌活性分析。结果发现:黑眶蟾蜍皮肤分泌物对革兰氏阳性菌——金黄色葡萄球菌、枯草芽孢杆菌的抑制作用较强,对革兰氏阴性菌中的嗜水气单细胞菌也表现出较强的抑制作用,对溶藻弧菌、副溶血弧菌、河流弧菌、大肠杆菌的抑制相对较弱。利用胰蛋白酶对黑眶蟾蜍皮肤抗菌肽水解后,其抗菌活性消失。将黑眶蟾蜍皮肤抗菌肽在37~95℃和pH 2.5~5.0下保温,发现其抗菌活性成分对热及酸耐受性较强。黑眶蟾蜍皮肤分泌物在低浓度无溶血活性。     

Evaluation of antioxidant and antibacterial activity of methanolic extracts of Gentiana kurroo royle

In this study our objective was to evaluate the antioxidant and antimicrobial activity of methanolic extracts of leaves and roots of Gentiana kurroo. The antioxidant activities of the extracts were examined using different biochemical assays namely diphenylpicrylhydrazyl (DPPH), nitroblue tetrazolium (NBT) and ferric reducing power (FRAP). In all the assays, root extract exhibited stronger antioxidant activity than that of leaves. The antibacterial activity of the extracts was also evaluated and MIC values were calculated by broth dilution method. Although, the extracts prevented the growth of both Gram positive and Gram negative bacteria, the MIC values of methanolic extract of the leaves were higher than those of the root extract. The antibacterial and antioxidant activity of the extracts was found to be positively associated with the total phenolic and flavonoid content of the extracts.     

Antibacterial Diphenyl Ether,Benzophenone and Xanthone Derivatives from Aspergillus flavipes

The extract of the strain Aspergillus flavipes DL‐11 exerted antibacterial activities against six Gram‐positive bacteria. During the following bioassay‐guided separation, ten diphenyl ethers ( 1 – 10 ), two benzophenones ( 11 – 12 ), together with two xanthones ( 13 – 14 ) were isolated. Among them, 4′‐chloroasterric acid ( 1 ) was a new chlorinated diphenyl ether. Their structures were elucidated by extensive spectroscopic data analysis, including IR, HR‐ESI‐MS, NMR experiments, and by comparison with the literature data. All compounds showed moderate to strong antibacterial effects on different Gram‐positive bacteria with MIC values that ranged from 3.13 to 50 μg/mL, but none of the compounds exhibited activity against Gram‐negative bacteria Vibrio parahaemolyticus ATCC17802 (MIC>100 μg/mL). In particular, the MICs of some compounds are at the level of positive control.     

枸杞多糖与黄芪多糖抑菌活性的研究*

目的:研究黄芪多糖和枸杞多糖的抑菌活性并探讨不同pH值对其抑菌活性的影响。方法:采用滤纸片扩散法,分析不同浓度黄芪多糖和枸杞多糖在不同pH值下对几种常见细茵和霉菌(大肠杆菌、沙门氏菌、金黄色葡萄球菌、黑曲霉、产黄青霉)的抑制效果。结果:对于细菌,枸杞多糖8mg/mL时出现抑菌圈,而黄芪多糖0.02 mg/mL时效果最佳;对于霉菌,随着枸杞多糖浓度的增大,抑菌圈的直径增大,而黄芪多糖0.02 mg/mL时效果最佳;当枸杞多糖和黄芪多糖在pH6的条件下,二者抑菌活性均最强。结论:枸杞多糖和黄芪多糖对细菌、霉菌都有一定的抑制效果,pH值可影响枸杞多糖和黄芪多糖的抑菌效果。     

纳米银/植物源复合抗菌剂的制备及其抑菌性能的研究

以硝酸银作为银源,水溶性淀粉作保护剂,丙酮酸钠作还原剂,氨水提供碱性环境来制备纳米银胶,并以聚乙烯吡咯烷酮(PVP)作分散稳定剂,复配红景天提取液和无患子提取液制备出纳米银/植物源复合抗菌剂。实验结果表明,纳米银胶或植物提取液仅对部分细菌或霉菌有较强抑制效果,而复合抗菌剂对细菌、霉菌均有很强抑制效果。在湿巾液中添加0.5%复合抗菌剂时,其对大肠杆菌,金黄色葡萄球菌和白色念珠菌的抗菌效率可达99%,且经过常温六个月、高温55℃一个月保存后,其抗菌活性分别可达到95%、90%左右,表明复合抗菌剂具有较强的抗菌效率及抗菌稳定性。     

Copper Oxide Nanomaterials Derived from Zanthoxylum armatum DC. and Berberis lycium Royle Plant Species: Characterization,Assessment of Free Radical Scavenging and Antibacterial Activity

Copper oxide nanomaterials were synthesized by a facile sustainable biological method using two plant species (Zanthoxylum armatum DC. and Berberis lycium Royle ). The formation of materials was confirmed by FT‐IR, ATR, UV‐visible, XRD, TEM, SEM, EDX, TGA and PL. The antibacterial activity was evaluated by agar well diffusion method to ascertain the efficacy of plant species extract and extract derived copper oxide nanomaterials against six Gram‐positive bacteria namely Staphylococcus aureus, Streptococcus mutans, Streptococcus pyogenes, Corynebacterium diphtheriae, Corynebacterium xerosis, Bacillus cereus and four Gram‐negative bacteria such as Klebsiella pneumonia, Escherichia coli, Pseudomonas aeruginosa and Proteus vulgaris against the standard drug, Ciprofloxacin for Gram‐positive and Gentamicin for Gram‐negative bacteria, respectively. In both cases, copper oxide nanomaterials were found to be sensitive in all the bacterial species. Sensitivity of copper oxide nanomaterials shows an be higher as compared to plant species extract against different bacteria. Scavenging activity of plant extracts along with nanomaterials have been accessed using previously reported protocols employing ascorbic acid as standard. Scavenging activity of copper oxide nanomaterials shows an increase with increase in concentration. The biological activity (bactericidal and scavenging efficiency) of plant derived copper oxide nanomaterials revealed that these materials can be used as potent antimicrobial agent and DPPH scavengers in industrial as well as pharmacological fields.     

抗菌肽的固相合成,分离纯化与构效关系的研究

应用手工固相ＤＣＣ／ＨＯＢｔ法合成ＣｅｃｒｏｐｉｎＢ、Ｓｈｉｖａｌ１、ＡＢＰ３、ＷＨＤ４种抗菌肽,各抗菌肽的Ｃ－端均为酰胺化,最终用ＨＰＬＣ分离纯化,这４种肽对大肠杆菌Ｋ１２Ｄ３１,野生型大肠杆菌,产气杆菌及４种植物病原菌青枯菌,临床致病理大肠杆菌,伤寒杆菌,硝酸盐杆菌均有明显的杀伤或抑制作用,对白血病细胞Ｋ５６０,肺癌细胞Ａ５４９也有杀伤作用,其中尤以ＷＨＤ杀伤作用最为明显,并用对其它３种肽不能     

Influence of medium components and fermentation conditions on the production of bacteriocin(s) by Bacillus licheniformis AnBa9

Recently, antibacterial peptides are gaining more attention as an alternative therapeutics and food and other products from spoilage and deterioration. Antibacterial peptide producing strains were isolated from sediments of slaughterhouse sewage wastes. One among them, identified as Bacillus licheniformis inhibited the growth of several gram positive bacteria. Response surface methodology with central composite rotary design was used for optimization of fermentation medium and conditions for antibacterial peptide production. Lactose, NH(4)NO(3), yeast extract and NaCl and environmental factors such as pH, temperature and incubation period were selected as variables. Among ingredients, high concentration of yeast extract and NaCl had a positive effect on antibacterial peptide production and specific activity, respectively. Alkaline pH and high temperature favoured the production of antibacterial peptide by B. licheniformis AnBa9. Under optimized condition, B. licheniformis AnBa9 produced 25-fold higher production of antibacterial peptide than the un-optimized condition. Biochemical characteristics of the antibacterial peptides of B. licheniformis AnBa9 revealed that they are of bacteriocin type.     

Bioactive stilbenes from a Bacillus sp. N strain associated with a novel rhabditid entomopathogenic nematode

Aims: The aim of the present study was to purify and characterize a natural antimicrobial compound from Bacillus sp. strain N associated with a novel rhabditid entomopathogenic nematode. Methods and Results: The cell‐free culture filtrate of a bacterium associated with a novel entomopathogenic nematode (EPN), Rhabditis (Oscheius) sp. exhibited strong antimicrobial activity. The ethyl acetate extract of the bacterial culture filtrate was purified by column chromatography, and two bioactive compounds were isolated and their chemical structures were established based on spectral analysis. The compounds were identified as 3,4′,5‐trihydroxystilbene (1) and 3,5‐dihydroxy‐4‐isopropylstilbene (2). The presence of 3,4′,5‐trihydroxystilbene (resveratrol) is reported for the first time in bacteria. Compound 1 showed antibacterial activity against all the four test bacteria, whereas compound 2 was effective against the Gram‐positive bacteria only. Compounds 1 and 2 were active against all the five fungi tested and are more effective than bavistin, the standard fungicide. The antifungal activity of the compounds against the plant pathogenic fungi, Rhizoctonia solani is reported for the first time. Conclusions: Cell‐free extract of the bacterium and isolated stilbenes demonstrated high antibacterial activity against bacteria and fungi especially against plant pathogenic fungi. We conclude that the bacterium‐associated EPN are promising sources of natural bioactive secondary metabolites. Significance and Impact of the Study: Stilbene compounds can be used for the control of fungi and bacteria.     

杨梅果实不同溶剂提取物抑菌特性的研究

目的探讨4种溶剂杨梅果实提取物对14种致病菌的抑菌作用,并对其中活性成分的含量进行测定和比较。方法利用常压浸提法制备杨梅果实的水、乙醇、乙酸乙酯和丙酮提取物;采用管碟法、琼脂平板稀释法测定各种杨梅提取物的抑菌活性,采用常规含量测定方法对各提取物中的主要成分及含量进行研究。结果4种杨梅果实提取物对革兰阴性和阳性菌均表现出了较强的抑菌活性,其中水提取物的抑菌活性最强。含量测定结果表明4种提取物的主要成分中总酚、黄酮含量以及总酸度相差较大,单宁含量差异较小。结论推测提取物中的主要抑菌成分为单宁类物质并确定杨梅果实的最佳提取溶剂为水。