枣核木醋液化学成分分析及其抑菌活性

为了充分利用枣核资源,采用干馏法（150～400 ℃）制得枣核木醋液,并采用气相色谱-质谱联用仪分析其化学成分,通过对大肠杆菌、青霉菌及石榴干腐病菌的抑菌实验评价其抑菌活性。结果显示,枣核木醋液中含有35 种化合物,主要为酚类、酮类、有机酸类、醛类和杂环化合物等,其中含量最多的是酚类、酮类化合物和有机酸,三者占总检出成分的71.01%。枣核木醋液对大肠杆菌、青霉菌及石榴干腐病菌均有抑制作用,并呈现剂量依赖效应,对3 种菌的最小抑菌浓度分别为1.25%、2.5%和0.625%。表明枣核木醋液具有较强的抑菌活性,初步分析酚类物质和有机酸是其抑菌的主要有效成分。     

In Vitro Assessment of Probiotic Properties of Lactobacillus Strains from Infant Gut Microflora

Lactobacillus isolates from infant feces were identified and investigated in vitro for their probiotic properties. The isolates belonged to the species L. acidophilus, L. rhamnosus, L. paracasei subsp. paracasei, L. fermentum, L. delbrueckii subsp. delbrueckii, L. cellobiosus, L. plantarum, L. brevis and L. crispatus. The strains were examined for acid and bile tolerance, adhesion to Caco-2 cells, antibiotic susceptibility and antimicrobial activity against selected enteric pathogens. According to the obtained results, a L. deblueckii subsp. delbrueckii strain was found to exhibit probiotic properties. Other strains from L. paracasei subsp. paracasei and L. fermentum group also could be further investigated as potential probiotic candidates.     

pH对费氏丙酸杆菌细菌素抑菌性的影响

以实验室保存的一株费氏丙酸杆菌CS1420(Propionibacterium freudenreichii CS1420)为试验菌株。首先考察了不同初始pH下对其发酵产细菌素的影响。结果表明:以大肠杆菌ATCC25922为指示菌,当培养基初始pH为6.0时,细菌素抑菌效果最好;以Saccharomyces cerevisiae 2-10515为指示菌,当培养基初始pH为5.5时,细菌素抑菌效果最好。然后用丙酸调节细菌素粗提物的pH进行抑菌试验,结果表明,pH对粗提得到的细菌素抑菌性影响很大,当用丙酸将细菌素溶液的pH调至5.5时,细菌素的抑菌活性有显著提高。     

黄精多糖抑菌及抗氧化性能研究

用滤纸片抑菌圈实验法研究了黄精多糖对常见的几种细菌的抑制作用。结果表明:黄精多糖对实验菌有明显的抑制作用。其中对金黄色葡萄球菌抑制作用最强,MIC=0.5%,抑菌圈直径为19.6mm,对大肠杆菌最弱,MIC=2.0%,抑菌圈直径为11.2mm。黄精多糖具有一定的抗氧化作用。     

精氨酸-共轭亚油酸抗氧化活性研究

测定了精氨酸-共轭亚油酸清除超氧阴离子自由基(O2-.)、羟自由基(.OH)和二苯代苦味肼基自由基(DPPH.)的能力,并与VC的抗氧化活性进行了比较。结果表明:精氨酸-共轭亚油酸对3种自由基的清除能力均与其浓度存在着量效关系;精氨酸-共轭亚油酸对O2-.有一定的清除作用,但清除能力低于VC;精氨酸-共轭亚油酸对.OH和DPPH.有较强的清除作用,且清除能力均高于VC。在精氨酸和共轭亚油酸的协同作用下,精氨酸-共轭亚油酸的抗氧化活性得到增强。因此,精氨酸-共轭亚油酸是一种有效的抗氧化剂。     

共轭亚油酸的生理活性及制备方法研究进展

旨在为进一步提高共轭亚油酸产量提供理论依据,总结概述了共轭亚油酸的生理活性与制备方法的研究进展。共轭亚油酸是一种天然存在于反刍动物体内的物质,具有降低胆固醇含量、抗癌、抗氧化、提高免疫力等重要生理功能,在减肥、癌症治疗、哮喘治疗等方面发挥了重要作用,在功能性膳食研发领域拥有巨大潜力。由于共轭亚油酸的天然含量与来源无法满足人们日常生活的需求,因此研究更高产率的共轭亚油酸的合成方法一直是热点内容。合成共轭亚油酸的方法主要有生物合成法和化学合成法,生物合成法中的微生物合成法和酶催化异构化合成法是近年来的研究热点。     

苯甲酸的酯化及其抑菌活性研究

对苯甲酸甲酯化的合成工艺条件及抑菌效果进行了研究。合成实验结果表明苯甲酸甲醇酯化混合液（ｌｍｏｌ：５ ｍｏｌ）在８５℃时酯化反应速度最快;不同类型酯化催化剂间适当组合对苯甲酸甲酯的合成可产生显著的增效作用。抑菌实验结果表明苯甲酸经酯化修饰后,可显著抑制微生物的生长,缩短对数生长期和减少微生物的生长量。     

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。     

溴代山梨酸的合成与抗菌作用研究

针对山梨酸使用过程中存在的问题 ,首次合成了溴代山梨酸 ,研究了它对不同种类微生物的抗菌性能 ,并与山梨酸的抗菌性能进行了比较。山梨酸经化学修饰合成溴代山梨酸后 ,抗菌作用显著增强 ,抗菌作用稳定性显著提高 ,半衰期延长了 3 3倍 ,在水中溶解性得到明显改善 ,具有一定的开发应用前景     

共轭亚油酸抗氧化性能的研究进展

介绍了近十余年来关于共轭亚油酸(CLA)抗氧化性能的研究以及CLA抗氧化性与其抗癌机理的关系，并对影响CLA氧化性能评价的因素进行了分析。CLA氧化性能的研究与评价，与试验体系、测定方法、CLA存在形式及浓度等诸多因素有关；CLA是否属于抗氧化剂仍然存在分歧。     

腐竹揭皮过程中理化参数变化趋势研究

本文探讨了腐竹揭皮过程中各种理化指标的变化趋势及其对腐竹品质的影响。研究表明,在揭皮过程中蛋白质浓度和豆浆固形物浓度分别从3％和5％上升到4．4％和12％,pH值从6．5下降到6．1,腐竹中蛋白质含量从50％下降到40．1％,腐竹的韧性则从280g下降到50g。     

对羟基苯甲酸酯衍生物的抗菌活性及其发展趋势

介绍了新型高效食品防腐剂对羟基苯甲酸酯衍生物的抗菌活性，阐述了对羟基苯甲酸酯衍生物的生产现状和在食品工业应用研究的发展趋势。     

不同取代度水溶性羧甲基茯苓多糖的制备、结构表征及体外抑菌活性

为提高茯苓多糖的水溶性和提高其生物活性,以一氯乙酸为羧甲基化试剂合成羧甲基茯苓多糖（carboxymethylated pachymaran,CMP）,并对不同取代度水溶性CMP进行结构表征及体外抑菌活性分析。结果表明：羧甲基化反应的最佳条件为反应温度65 ℃、反应时间4 h、反应溶剂乙醇体积分数80%、反应物茯苓多糖-氢氧化钠-一氯乙酸物质的量比为1∶3.5∶1.75,此条件下,CMP的平均取代度为0.724;通过调控反应条件可制备出不同取代度的CMP,取代度范围为0.350～0.728;红外光谱分析结果表明茯苓多糖衍生化成功;高效凝胶渗透色谱法测定取代度越高,分子质量越小;取代度越高的CMP Zeta电位绝对值越大,粒径先增大后减小,中性糖含量越低,热稳定性先增大后减小;核磁共振光谱分析结果表明羧甲基衍生化反应主要发生在C6位的羟基上;扫描电镜显示取代度越高,空间结构越紧密,裂解情况越严重。体外实验发现,CMP对食源性致病菌的抑制能力随取代度的增加而增强,对革兰氏阳性菌的抑制能力强于革兰氏阴性菌。     

Novel bacteriocins produced by Lactobacillus fermentum strains with bacteriostatic effects in milk against selected indicator microorganisms

The aim of this work was to isolate and characterize bacteriocins produced by 2 Lactobacillus fermentum strains isolated from artisanal Mexican Cocido cheese. Fractions (F ≤3 kDa) obtained from cell-free supernatants of Lb. fermentum strains J23 and J32 were further fractionated by reversed-phase HPLC on a C18 column. Antimicrobial activities of F ≤3 kDa and bacteriocin-containing fractions (BCF), obtained from fractionation of F ≤3 kDa against 4 indicator microorganisms, were determined by the disk diffusion method and growth inhibition in milk. Subsequently, isolated BCF were analyzed by reversed-phase HPLC tandem mass spectrometry. Results showed that BCF presented antimicrobial activity against the 4 indicator microorganisms tested. For J23, one of the fractions (F3) presented the highest activity against Escherichia coli and was also inhibitory against Staphylococcus aureus, Listeria innocua, Salmonella Typhimurium, and Salmonella Choleraesuis. Similarly, fractions F3 and F4 produced by J32 presented antimicrobial activity against all indicator microorganisms. Furthermore, generation time and growth rate showed that F3 from J23 presented significantly higher antimicrobial activity against the 4 indicator microorganisms (2 gram-positive and 2 gram-negative) when inoculated in milk compared with F3 from J32. Interestingly, this fraction presented a broader antimicrobial spectrum in milk than nisin (control). Reversed-phase HPLC tandem mass spectrometry analysis revealed the presence of several peptides in BCF; however, F3 from J23 that was the most active fraction of all presented only 1 bacteriocin. The chemical characterization of this bacteriocin suggested that it was a novel peptide with 10 hydrophobic AA residues in its sequence and a molecular weight of 2,056 Da. This bacteriocin and its producing strain, J23, may find application as a biopreservative against these indicator microorganisms in dairy products.     

共轭亚油酸的生理功能及提高其在乳制品中含量的途径

概述共轭亚油酸(CLA)的生理功能,及提高其在乳制品中CLA的途径,如选育高产CLA的动物品种、研发新饲料、控制和改进加工条件等.     

抑制铜绿假单胞菌耐药菌株中药活性的研究

目的研究14种中药水提物对铜绿假单胞菌的质控菌株和耐药菌株的体外抑菌作用。方法先用纸片扩散法验证分离所得到的铜绿假单胞菌对庆大霉素和丁胺卡那霉素的耐药性,再用平板倍比稀释法测定中药水提物对铜绿假单胞菌质控菌株和耐药菌株的最低抑菌浓度（MIC）。结果苦参、石榴皮和鱼腥草对质控菌株和耐药菌株无抑菌作用（MIC〉100mg/mL）;金银花、蒲公英和黄芩对耐药菌株的抑菌作用明显优于对质控菌株,其他中药水提物对2种菌株的抑菌作用相似,其中西青果和石斛的抑菌作用最强（MIC=3.125 mg/mL）。结论多种中药水提物对铜绿假单胞菌具有显著的抑菌作用,尤其是对耐药菌株具有抑菌作用,表明中药在对抗细菌耐药性方面具有重要的开发价值。     

Role of the conjugated linoleic acid in the prevention of cancer

There are multiple lines of evidence that a variety of natural fatty acids are effective in health promotion. Among these fatty acids, conjugated linoleic acid (CLA)--a collective term referring to a mixture of positional and geometric isomers of linoleic acid (LA, cis-9, cis-12-octadecadienoic acid)--is currently under intensive investigation due to its health-promotion potential. The antitumor activity of CLA is of special interest, since it shows inhibitory effects against multistage carcinogenesis at relatively low dietary levels. Many studies using in vivo and in vitro models have shown that CLA suppresses the development of multistage carcinogenesis at different sites. The research to date on CLA has provided a vast amount of information about the mechanism on how CLA functions in the prevention of cancer. This article discusses characteristics of CLA in the prevention of cancer in both in vivo and in vitro studies and the possible underlying chemoprevention mechanisms.     

水翁皮水煎液抗菌作用研究

目的观察水翁皮水煎液的抗菌活性。方法采用纸片法对不同细菌和真菌进行抗菌活性测定,并采用琼脂平板稀释法和试管稀释法分别测定其最低抑菌浓度（MIC）和最低杀菌浓度（MBC/MFC）。结果水翁皮水煎液对各实验菌均有不同程度的抑制作用,对金黄色葡萄球菌、痢疾杆菌的抑制作用最强;对红色毛癣菌和须癣毛癣菌有明显的抑制作用。结论水翁皮水煎液具有良好的体外抗菌作用。     

Molecular cloning,expression and characterization of bile salt hydrolase from Lactobacillus rhamnosus E9 strain

Bile salt hydrolase (BSH) enzyme, commonly found in probiotic bacteria of gut origin, catalyzes the hydrolysis of glycine and/or taurine-conjugated bile salts allowing for colonization of the bacteria in the gut and contributing to a decrease in levels of cholesterol. However an excessive deconjugation of tauro-conjugated bile salts and production of secondary bile acid can have harmful side-effects. The aim of this study was to characterize the activity of BSH enzymes from Lactobacillus rhamnosus E9, a popular probiotic strain. The bsh gene was cloned, expressed, purified and characterized in Escherichia coli BLR(DE3) strain. The hydrolysis activities and substrate specificities of the recombinant BSH (rBSH) enzyme were examined using six different bile acids. Nucleotide sequence analysis results indicated that the bsh of E9 contained an open reading frame (ORF) of 1014 and nucleotides encoding a 338-amino acid protein with a molecular weight of 37 kDa. Five catalytically important amino acids and the amino acid motifs located around the active site were highly conserved. The rBSH showed a slight preference towards glycine-conjugated to tauro-conjugated bile salts. This confirms that it is a safe strain for probiotics and its preference for glycine-conjugated bile salts should be further investigated.     

阿魏酸化学修饰溶菌酶及扩展抑菌谱的研究

为了使溶菌酶扩展抑菌谱,同时作用于革兰氏阳性菌和革兰氏阴性菌,本文采用了阿魏酸修饰溶菌酶。采用EDAC作为缩合剂,使溶菌酶赖氨酸残基上的ε-氨基共价结合阿魏酸的羧基,形成一定程度的阿魏酸修饰酶。结果显示:与天然溶菌酶相比,修饰酶的酶活力略有下降,但是修饰酶扩展了抑菌谱,对革兰氏阴性菌的抑菌作用增强。修饰酶对大肠杆菌和沙门氏菌的最小抑菌浓度均为0.5mg/mL,而对金黄色葡萄球菌的抑菌作用略有下降。