植物病原细菌的细菌素

植物病原细菌的细菌素吴健胜,王金生（江苏南京农业大学植保系,南京２１００９５）细菌素是一种细菌的某些菌系所产生的对该种细菌的另一些菌株或关系较近的细菌有杀伤作用,非复制性的含蛋白的抗菌物质［１］。继１９４６年Ｆｒｅｄｅｒｉｃｑ报道大肠杆菌产生的大肠杆...     

马尾松毛虫肠道产细菌素细菌的筛选及抑菌特性

[背景]细菌素是一类由细菌产生的抗菌肽活性物质,对多种致病菌有抑制和杀灭作用.昆虫是世界上种类最多、肠道菌群资源最为丰富且多样的动物类群之一.昆虫肠道很可能蕴含着丰富的产细菌素菌种资源.[目的]以马尾松毛虫(Dendrolimuspunctatu)幼虫为研究材料,对其肠道细菌进行分离、培养和鉴定,获得对典型致病菌有明显...     

嗜酸乳杆菌产细菌素生物学特性的研究

嗜酸乳杆菌在MRS培养基中培养得到的细菌素经30、60、90、121℃处理20min后,活性几乎不变,对以金黄色葡萄球菌为代表的革兰阳性菌、大肠埃希菌为代表的革兰阴性菌有明显的抑制作用,Tricine—SDS—PAGE和不同pH值抑菌实验测定结果证明,嗜酸乳杆菌细菌素是一组低分子量,并在pH2—4时有抑菌作用的活性物质。     

乳酸菌细菌素的分子生物学研究进展

乳酸菌是一大类发酵糖产生大量乳酸的兼性厌氧菌 ,广泛应用于医药、食品、发酵等工业 ,主要包括乳杆菌( L actobacillus)、乳球菌 ( L actococcus)、明串珠菌( L euconostoc )、片球菌 ( Pediococcus )、链球菌( Streptococcus)、肠球菌 ( Enterococcus)、双歧杆菌( Bifidobacterium)和肉食杆菌 ( Carnobacterium)等属 [1 ]。许多乳酸菌除产生乳酸、乙酸和双乙酰外 ,还可产生一些具有抑菌或杀菌作用的细菌素 ( bacteriocin) ,在食品防腐保鲜中起重要作用 [2 ] 。细菌素的含义可以这样理解。细菌素是由某些细菌在代谢过程中通过核糖体合…     

细菌mRNA的提取方法

mRNA提取技术不仅是分子生物学技术的重要组成部分 ,也是功能基因组学科研技术的重要基础。随着细菌的后基因组时代的到来 ,寻求一种有效的提取细菌mRNA的方法成为迫切需要解决的问题。介绍细菌mRNA的特点、提取方法、标记和稳定性问题。     

乳酸菌细菌素研究进展

乳酸菌是一类能从可发酵性碳水化合物产生大量乳酸的革兰氏阳性细菌的通称。它们在人、动物体内及人类环境中是一类重要的微生物。一些定居在嘴、鼻粘膜中;一些定居在消化道、肠道（双歧菌、肠球菌和一些乳杆菌）和阴道粘膜中（一些特殊的乳杆菌）。在这些生境小区里,它们中大多数不仅不致病,相反有益,可以抑制一些腐败菌和病原菌,从而维持体内这些小生境尤其是肠道内正常的微生态平衡［’］。同时,乳酸菌也是一类重要的工业微生物,广泛应用于轻工业、医药工业、食品工业、发酵工业和饲料工业上。通常在食品和发酵工业中应用的乳酸菌…     

不同提取工艺对家蝇幼虫蛋白粗提液抗菌活性的影响

利用不同条件提取诱导过的家蝇Musca domestica 3龄幼虫的总蛋白,并用平板扩散法测定所得蛋白粗提液的抗菌活性。结果表明,收集幼虫时的处死温度、沸水浴时间及提取液的pH值均对家蝇幼虫粗提液的抗菌活性有明显的影响。     

环境因素对PlnA诱导类植物乳杆菌产生细菌素效果的影响

【目的】研究人工合成的PlnA (Plantaricin A)诱导类植物乳杆菌L-XM1细菌素合成的功能及环境条件对其诱导效果的影响。【方法】制备类植物乳杆菌L-XM1 Bac?培养物, 用人工合成的PlnA对其进行诱导, 确定PlnA在类植物乳杆菌L-XM1细菌素合成中的作用, 并通过比较不同温度、pH以及NaCl浓度、乙醇浓度条件下PlnA的诱导活性, 研究环境条件对PlnA诱导效果的影响。【结果】在不同温度及pH条件下, 自诱导肽PlnA的诱导活性有很大的差异, 较高的培养温度及pH有利于其诱导活性的发挥。不同浓度的NaCl对PlnA的诱导活性影响不大。乙醇可以减弱PlnA的诱导活性, 高浓度的乙醇完全抑制PlnA的诱导活性。6%乙醇对细菌素合成的抑制可以被700 μg/L的PlnA消除, 含有8%乙醇的培养基中, 恢复细菌素的合成需要浓度高达1 000 μg/L的PlnA。【结论】环境条件可以影响诱导肽PlnA的诱导活性, 乙醇对细菌素合成的抑制可以通过增大PlnA的浓度消除。     

细菌素的制备及其应用

近年来,具有抑菌活性的细菌素被发现在食品防腐保鲜、疾病治疗和其他许多相关方面有着广泛的应用价值,各种制备细菌素的方法也被广泛报道。本文概述了细菌素的制备方法以及其在诸多领域中的应用。     

细菌素的抗细菌耐药研究及应用现状

随着青霉素等抗生素的问世,人类因细菌感染所致疾病的死亡率大为降低;但在抗生素广泛应用至今,我们又面临着细菌耐药日趋严重、耐药菌感染难以控制、新抗生素研发脚步迟滞的严峻局势。如何应对这一全球性的难题,研究者们殚精竭虑,力求在抗生素以外寻求新的突破,有着比抗生素更悠久历史、同样具有抗菌活性的细菌素引起了研究者们的重视。但抗菌谱、产量等问题使细菌素的应用受到了限制,打破瓶颈成了当下研究的热点。本文主要对细菌素的研究现状、应用及异源表达做了相关综述。     

酶浸提取方法对士的宁产率的影响

目的：研究了纤维素酶在提取生物碱过程中的应用。方法：采用酶浸法和氯仿法两种不同的工艺提取马钱子生物总碱,高效液相色谱法（HPLC）测定了马钱子生物总碱中士的宁的含量。结果：酶浸法提取士的宁和氯仿法提取士的宁的含量分别为1．83％、1．32％;酶浸法和氯仿法提取马钱子生物总碱的产率分别为：2．85％、1．86％。     

Effect of Different Extraction Methods on Osmanthus Oil Quality

用超临界流体萃取法(SCFE)、可食用石油醚和酒精抽提蒸馏三种不同的抽提方法,提取了咸宁桂花品种——银星的花精油;气质联用(GC-MS)分析不同方法提取精油的香气成分及其相对含量.结果表明:SCFE提取的精油得率最高(0.19％),紫罗兰酮、醇类的相对含量高达36.99％;石油醚浸提结果次之(0.13％),酒精抽提法不可取(0.07％).     

不同提取方法对桂花精油品质的影响

用超临界流体萃取法(SCFE)、可食用石油醚和酒精抽提蒸馏三种不同的抽提方法,提取了咸宁桂花品种——银星的花精油;气质联用(GC-MS)分析不同方法提取精油的香气成分及其相对含量。结果表明:SCFE提取的精油得率最高(0.19%),紫罗兰酮、醇类的相对含量高达36.99%;石油醚浸提结果次之(0.13%),酒精抽提法不可取(0.07%)。     

不同提取条件对苦荞籽粒中芦丁降解的影响

本实验研究了不同提取条件对苦荞籽粒中芦丁含量的影响,经HPLC分析,浓度高于40％(v／v)的乙醇对芦丁降解酶有明显的抑制作用,其中90％乙醇的抑制作用最强。苦荞粉与水接触的时间强烈影响芦丁的含量．接触1min芦丁含量迅速由原来的79．72％下降到32．21％,即约60％的芦丁被降解。在pH1．0～11．0范围内．芦丁降解酶具有很强的抗酸碱性。当温度大于60℃时．芦丁降解酶开始缓慢失活,芦丁得以较好保存．高于70℃时芦丁保存率更高;当温度为90℃,芦丁保存率约为对照值的80％。该研究结果对于苦荞芦丁的提取和苦荞食品的加工具有重要的理论意义和实际指导价值。     

Bacteriocin Production and Different Strategies for Their Recovery and Purification

Bacteriocins from lactic acid bacteria (LAB) are a diverse group of antimicrobial proteins/peptides, offering potential as biopreservatives, and exhibit a broad spectrum of antimicrobial activity at low concentrations along with thermal as well as pH stability in foods. High bacteriocin production usually occurs in complex media. However, such media are expensive for an economical production process. For effective use of bacteriocins as food biopreservatives, there is a need to have heat-stable wide spectrum bacteriocins produced with high-specific activity in food-grade medium. The main hurdles concerning the application of bacteriocins as food biopreservatives is their low yield in food-grade medium and time-consuming, expensive purification processes, which are suitable at laboratory scale but not at industrial scale. So, the present review focuses on the bacteriocins production using complex and food-grade media, which mainly emphasizes on the bacteriocin producer strains, media used, different production systems used and effect of different fermentation conditions on the bacteriocin production. In addition, this review emphasizes the purification processes designed for efficient recovery of bacteriocins at small and large scale.     

CELⅠ酶的粗提取及其活性检测

CEL I酶是第一个从真核生物中提取的用于高效特异切割DNA双链碱基错配和DNA扭曲的内切酶, 因而也是TILLING技术中用到的一种关键酶。文章对CELI酶的粗提取及其活性检测进行了研究。错配切割实验表明, CELI酶在包含有G→A点突变的杂合双链中, 能有效地在错配位点进行切割, 并可以通过ABI377测序仪获得直观的检测结果, 从而可以用于TILLING分析。     

Effect of the Medium on Bacteriocin Production Among Strains of Streptococcus mutans

Bacteriocin production by Streptococcus mutans was shown to be influenced by the medium on which the strains were grown, and it is suggested that selected media might be useful in bacteriocin typing.     

不同提取剂对麦醇溶蛋白提取效果的电泳比较

以大麦、小麦品种为材料,分别采用醇溶蛋白提取剂乙醇、乙二醇、2-氯乙醇、2-巯基乙醇、尿素等配成不同浓度的单一组分提取剂和复合提取剂,在同一条件下提取大麦和小麦去胚种子的醇溶蛋白,通过A-PAGE分离样品液发现,单一组分提取剂中25％的2-氯乙醇效果较好,5％的2-巯基乙醇效果较差;复合提取剂中由2-氯乙醇和2-巯基乙醇组成的提取剂效果最好。这种复合提取剂制备的样品液经电泳后,在图谱中条带丰富,带型清晰,无论对大麦还是小麦种子,都是最佳的醇溶蛋白提取剂。     

Stimulation of Bacteriocin Production by Dialyzed Culture Media from Different Lactic Acid Bacteria

The cross-effects of dialyzed postincubates (with a cut-off at 1000 Da) on the biomass and bacteriocin production of six strains of lactic acid bacteria were studied, and a predominance of stimulating responses was found, the characteristics of which suggested merely nutritional effects or the presence of precursor fragments of the bacteriocins. Additionally, cluster analysis of the detected responses provides an approach to define groups of highly compatible (potential consortia) or doubtfully compatible strains of lactic acid bacteria. Such a definition, which does not claim taxonomic value, has practical interest, however, in cases (e.g., silage production) in which it is convenient to use mixed inocula including strains able to establish positive interactions.     

Concomitant Synthesis of Bacteriocin and Bacteriocin Inactivator from Serratia marcescens

We have found that Serratia marcescens strain P & S is bacteriocinogenic. However, the phenotypic expression of bacteriocin activity depends upon the temperature at which the cells are grown. When the organism is grown at 30 to 37 C, no bacteriocin activity can be demonstrated, whereas when it is grown at 39 C bacteriocin activity is readily observed. It appears that the P & S strain concomitantly synthesizes a bacteriocin and a substance which not only can inactivate the bacteriocin but also has a high activation energy for inactivation. This inactivator readily loses its activity when heated at 39 C for 1 hr. Two mutants were isolated from the P & S strain which can produce active bacteriocin when grown at temperatures from 30 to 39 C. It is significant that these mutants have considerably less bacteriocin inactivator. The data suggest that the inactivator is an extracellular protease. The ability of one of these mutants, JF58-12, to produce active bacteriocin at temperatures between 30 and 39 C is a stable property, whereas in the other mutant, JF48W, this property is unstable. JF48W was selected from the P & S strain in two steps: first a streptomycin-resistant variant (strain A-10) was isolated and from this mutant a strain (JF48W) was isolated which not only synthesized little of the inactivator but also did not synthesize the red pigmnet prodigiosin. This latter pleiotropic mutant appears to revert in one step to a phenotype similar to the P & S strain, since it is streptomycin-sensitive and produces prodigiosin and normal amounts of inactivator and the demonstration of bacteriocin activity is temperature-dependent.