抗防腐剂型微生物培养基研究

食品饮料中含有山梨酸、山梨酸钾、苯甲酸及苯甲酸钠等防腐剂会对其中的细菌和真菌的检出造成严重干扰,把测定体系的抗防腐剂指数控制在８１．１～９４．５之间,可较好地消除防腐剂对微生物生长的抑制。防腐剂解抑剂Ⅲ的抗防腐剂指数为９２．３４,对细菌和真菌的生长无抑制作用,加入经改良和优化的普通培养基后,制得５种抗防腐剂型培养基,在灭菌前后和一年保存期内,它们的抗防腐剂指数基本保持不变。与普通培养基比较,当采用大样倾注平板法和液体大样法检测含有防腐剂的样品时,抗防腐剂型培养基可极大地提高样品中的细菌和真菌的检出率。     

抗防腐剂型微生物培养基研究*

食品饮料中含有山梨酸、山梨酸钾、苯甲酸及苯甲酸钠等防腐剂会对其中的细菌和真菌的检出造成严重干扰,把测定体系的抗防腐剂指数控制在８１．１～９４．５之间,可较好地消除防腐剂对微生物生长的抑制。防腐剂解抑剂Ⅲ的抗防腐剂指数为９２．３４,对细菌和真菌的生长无抑制作用,加入经改良和优化的普通培养基后,制得５种抗防腐剂型培养基,在灭菌前后和一年保存期内,它们的抗防腐剂指数基本保持不变。与普通培养基比较,当采用大样倾注平板法和液体大样法检测含有防腐剂的样品时,抗防腐剂型培养基可极大地提高样品中的细菌和真菌的检出率。     

发酵法生产丙酸的研究进展

目前广泛使用的三大防腐剂苯甲酸、丙酸、山梨酸中,丙酸是世界上公认的最经济实惠、安全有效的食用性防腐剂,它可有效抑制霉菌、嗜氧芽孢杆菌、革兰氏阴性杆菌且对人畜基本无害,因而被广泛运用在谷物、饲料和食品的防腐保鲜中。另外还可用来合成医药、塑料、农药、香料及除草剂等产品。目前世界年生产能力达２０万吨且呈上升趋势。丙酸最早曾用糖蜜淀粉发酵制备,后随着化工技术的提高,目前世界上已能用乙烯合成法、乙烯碳基化法、丙烯还原法等生产。但随着现代生物技术的迅猛发展,发酵法生产经济性的日渐提高,近年来国外这方面的研究…     

新型防腐剂在淋洗类日化产品中的应用

对三种新型日化防腐剂华科-CAP、华科-11M及华科-11N进行了微生物抑制特性测试,在不同的使用浓度下,对其在淋洗类产品中进行了微生物挑战试验。结果表明,单独使用时浓度为0.6%～0.8%的三种防腐剂均通过了微生物挑战性试验,并优选出了具有良好抑制细菌、真菌生长效果的防腐剂配方。     

乳酸钠、茶多酚与壳聚糖协同抑制铜绿假单胞菌的效果

以铜绿假单胞菌为研究对象,通过常量肉汤稀释法和琼脂扩散法探讨乳酸钠和茶多酚、壳聚糖复配后对铜绿假单胞菌是否有协同抑制效果。利用响应面方法对3种复合防腐剂的抑菌效果进行优化。应用BoxBehnken试验设计,建立3种防腐剂的二次多项式回归方程模型并进行分析。结果表明:三者对铜绿假单胞菌的抑菌效果(从大到小)顺序为乳酸钠、壳聚糖、茶多酚;乳酸钠和茶多酚交互作用极显著(p0.01),存在明显的拮抗作用;乳酸钠和壳聚糖交互作用显著(p0.05),二者存在明显的协同作用;而茶多酚和壳聚糖之间交互作用不显著(p0.05)。在乳酸钠62.50 mg/mL、壳聚糖3.17 mg/mL的条件下复合防腐剂对假单胞菌的抑菌圈达到最大,抑菌效果最好。     

复合生物防腐剂杀菌效果优化及草莓保鲜效果研究

为研究复合生物防腐剂(ε-聚赖氨酸、乳酸链球菌素、生物表面活性素质量百分比1:1:1混合)能否代替化学性食品防腐剂,通过敏感性测定、杀菌优化实验,草莓防腐应用试验,研究了其对指示菌点青霉的抑制效果。结果表明,点青霉对复合生物防腐剂较为敏感,其抑菌圈直径为18.73mm。利用响应曲面法对复合防腐剂杀灭点青霉孢子作用优化后,在温度为4.40℃、作用时间为9.95h、浓度为0.96mg/mL的情况下可以将基质中的点青霉孢子降低4个数量级。草莓防腐试验表明在自然贮藏10d其最高防效可达85.2%,防腐效果显著。     

农药助剂对苏云金杆菌毒力的影响及新液剂研制

研究了２０种化学物质对苏云金杆菌的毒力影响,分析了由乳化剂、湿润剂、防腐剂配制的几种不同农药助剂组合与该菌芽孢晶体混合物在不同贮存期的毒力变化及芽孢存活率。从供试的助剂组合中获得了一种最佳组合,其各项指标均优于中华人民共和国农业行业标准中所规定的各项要求,可发展成一种新的苏云金芽孢杆菌液剂。     

防腐抑菌中药的微量快速筛选法研究及其应用

本文探讨了筛选防霉防腐中药的微量快速筛选方法。试用MTT微量快速比色分析来测定药物对细菌和酵母菌的抑制作用,用培养板连续稀释法代替传统的试管稀释法测定药物抑制霉菌的作用。此法具有操作方便、节省材料、客观可靠、快速等优点。用此法筛选了几种传统食品类中药,其中以丁香抗霉菌作用最佳,乌梅对细菌、酵母有较明显的抑制作用,可作为食品防毒防腐剂。     

用香料油充当奶油制品防腐剂

目前,消费者对食品的营养价值和添加剂的安全性愈来愈重视。人们普遍认为天然食品添加剂比合成物的安全性高。例如,从枯茗(Cuminum cyminum L.)和百里香(Thymus vulgarius L.)的果实和叶子中,用蒸馏法提取的香料油便可充当奶油食品防腐剂。它可以抑制细菌、酵母和真菌     

微生物源天然防腐剂在食品上的应用研究

微生物源天然防腐剂是理想的天然食品防腐剂,具有安全、无毒、高效、无副作用的特点,符合未来食品防腐的发展与使用要求,在食品工业中的应用越来越广泛.该文对天然微生物源防腐剂的来源分类、抑菌特性、抑菌机理及适用范围进行了系统的研究分析与论述.有针对性地对目前两种应用最为广泛的微生物源天然防腐剂乳酸链球菌素和纳他霉素予以介绍,同时对微生物源天然防腐剂使用过程中遇到的问题提出了对策建议.对天然防腐剂的应用与发展具有现实和指导意义.     

Modulating effect of new potential antimelanomic agents, spin-labeled triazenes and nitrosoureas on the DOPA-oxidase activity of tyrosinase

The modulating effect of newly synthesized alkylating spin labeled triazene and spin labeled nitrosourea derivatives on the DOPA-oxidase activity of mushroom tyrosinase has been investigated by Bumett's spectrophotometric method (Burnett et al., 1967). All spin labeled triazenes have exhibited activating effect on DOPA-oxidase activity of tyrosinase, whereas clinically used triazene (DTIC), which does not contain nitroxide moiety, have showed inhibiting effect. At the same experimental conditions the spin labeled aminoacid nitrosoureas have showed dual effect - activating, in the beginning of the enzyme reaction and inhibiting later on. It is deduced that the activating effect of the spin labeled compounds is due to the nitroxide moiety and the inhibiting effect of all compounds depends on their half-life time. This study might contribute to make more clear the mechanism of action of the new compounds and on the other hand would come in quite useful as a preliminary prognosis for their antimelanomic activity.     

Isolation of DNA from plants high in polyphenolics

DNA suitable for digestion with restriction endonucleases has been isolated fromTheobroma cacao, a plant high in polyphenolic compounds, and several other plant taxa using the method presented in this paper. The method relies on concentrating nuclei away from most of the cytoplasmic components and inhibiting the formation of oxidized polyphenolic compounds and their interaction with the DNA fraction in the remaining steps.     

XIAP 基因在肿瘤中的研究进展

XIAP(X链锁凋亡抑制蛋白,X-linked inhibitor-of-apoptosis protain)是凋亡抑制蛋白(IAPs)家族中最有效力的caspase抑制物,具有抑制细胞凋亡,参与肿瘤的发生、发展。本文就XIAP在肿瘤中的作用机制、表达及治疗情况做一综述,有望为肿瘤的诊断及治疗提供一个新方法。     

植物源抗菌肽的研究进展

植物抗菌肽是植物自身合成的能够防御环境中微生物侵害的一类小分子多肽.它们大都是阳离子多肽,有较好的热稳定性.根据作用位点和抗菌机理的不同,植物抗菌肽可分为三大类:第一类通过干扰微生物细胞壁的合成来抑制微生物生长;第二类作用于质膜使其产生穿膜孔洞,从而导致微生物因细胞物质外泄受损;第三类则通过抑制某些细胞器的作用而起到抑菌的效果.本文从抗菌肽的作用机理及其分类等方面对植物源抗菌肽的研究进展进行了综述.     

Technique review: how to use RNA interference.

RNA interference (RNAi) has been rapidly adopted as a general method for inhibiting gene expression in most laboratory organisms. This paper discusses how libraries of RNAi reagents are being used to perform genome-wide reverse genetic screens in both model organisms and mammalian cells. Guidelines for designing effective small interfering RNAs and appropriate controls for mammalian RNAi experiments will also be discussed.     

Modification of the agarose drop micromethod for studying mouse macrophage migration inhibition factor

A modification of the drop agarose micromethod for the study of the factor inhibiting the migration of mouse macrophages is proposed. The syngeneic system was used instead of type RPMI-1640 complex culture media and calf embryonal serum, commonly used in the work with mouse macrophages. The production of the factor inhibiting the migration of macrophages by sensitized lymphocytes from mice of different strains has been shown to occur in vitro under the influence of pertussis corpuscular antigen. The method of obtaining supernatant containing macrophage migration inhibiting factor, from immune mouse lymphocyte culture is proposed. This supernatant may be used for, the analysis of the above-mentioned factor and other lymphokins.     

RANKL increases the level of Mcl-1 in osteoclasts and reduces bisphosphonate-induced osteoclast apoptosis in vitro

Introduction  

Bisphosphonates are the most widely used class of drug for inhibiting osteoclast-mediated bone loss, but their effectiveness at preventing joint destruction in rheumatoid arthritis has generally been disappointing. We examined whether the ability of bisphosphonates to induce osteoclast apoptosis and inhibit bone resorption in vitro is influenced by the cytokine receptor activator of nuclear factor-kappa B ligand (RANKL), an important mediator of inflammation-induced bone loss.     

PCR inhibitors – occurrence,properties and removal

The polymerase chain reaction (PCR) is increasingly used as the standard method for detection and characterization of microorganisms and genetic markers in a variety of sample types. However, the method is prone to inhibiting substances, which may be present in the analysed sample and which may affect the sensitivity of the assay or even lead to false‐negative results. The PCR inhibitors represent a diverse group of substances with different properties and mechanisms of action. Some of them are predominantly found in specific types of samples thus necessitating matrix‐specific protocols for preparation of nucleic acids before PCR. A variety of protocols have been developed to remove the PCR inhibitors. This review focuses on the general properties of PCR inhibitors and their occurrence in specific matrices. Strategies for their removal from the sample and for quality control by assessing their influence on the individual PCR test are presented and discussed.     

Synthesis and screening of 3-MA derivatives for autophagy inhibitors

Autophagy is a conserved degradation process, which plays important pathophysiological roles. The lack of effective inhibitors of autophagy has been an obstacle in both basic research and understanding the physiological role of autophagy in disease manifestation. The most widely used inhibitor, 3-methyladenine (3-MA), is poorly soluble at room temperature and is effective only at high concentrations. In this study, we synthesized a library of small compounds by chemically modifying 3-MA and screened this library for autophagy inhibitors. Three 3-MA derivatives generated through this approach showed improved solubility and effectiveness in inhibiting autophagy. We demonstrated that chemical modification of an existing autophagy inhibitor is an effective method to generate improved autophagy inhibitors.     

Comparison of methods used for the determination of cholinesterase activity in whole blood

Cholinesterases (ChEs) are classified as either acetylcholinesterase (AChE) or butyrylcholinesterase (BChE) based on their substrate and inhibitor specificity. Organophosphate and carbamate compounds commonly represented by herbicides, pesticides, and nerve gases irreversibly inhibit ChEs. Therefore, exposure to organophosphates and carbamates is normally assessed by measuring ChE activity in blood. There are two approaches for measuring AChE and BChE activity present in whole blood: (1) separating blood into erythrocytes, which contain only AChE, and plasma which contains only BChE, to measure their activity individually, or (2) use a BChE-specific inhibitor to measure the activity of AChE in whole blood. A number of studies have reported the use of different inhibitors for the simultaneous measurement of AChE and BChE activities. However, the inhibitors used for completely inhibiting BChE activity also inhibited AChE activity leading to errors in reported values. The goal of this study was to find the most accurate and simple method for the simultaneous determination of AChE and BChE activity in animal whole blood. Solutions containing human AChE and BChE in various proportions were prepared and AChE and BChE activities were measured using three reported methods. Results demonstrate that ethopropazine and (-) huperzine A appear to be the most specific ChE inhibitors. Preliminary results with human and animal whole blood suggest that 20muM ethopropazine and 500nM (-) huperzine A can be used for measuring AChE and BChE activities across species.