高产2,5-二甲基-4-羟基-3(2H)-呋喃酮(DMHF)酵母菌株的选育

从酒曲中筛选到1株高产2,5-二甲基-4-羟基-3(2H)-呋喃酮(DMHF)的酵母菌株(SX-21).高浓度NaCl和外源添加1,6-二磷酸果糖有利SX-21菌合成DMHF,其产量为100mg/L,达到文献报道的最高产量.经NTG诱变,筛选到1株突变株(NTG-SX-103),其产量提高到320 mg/L.SX-21菌株经18S rRNA鉴定为季也蒙毕氏酵母.     

溴化呋喃酮对单增李斯特菌生物膜形成及黏附作用的影响

目的:为了预防控制单增李斯特菌的污染,研究群体感应抑制剂3,4-二溴-2(5H)-呋喃酮在亚抑菌浓度下对单增李斯特菌生物膜形成的调控及黏附作用。方法:采用倍比稀释法确定抑制剂的最小抑菌浓度(MIC)和最低致死剂量(MBC),研究在亚抑菌浓度MIC,5MIC,10MIC时,单增李斯特菌生长曲线、细菌总蛋白含量、胞外多糖含量变化规律。通过结晶紫染色法观察生物膜形成情况,计算抑制率;通过细胞黏附试验测定对黏附率的影响。结果:3,4-二溴-2(5H)-呋喃酮对单增李斯特菌的MIC为25μg/mL,MBC为400μg/mL;在工作质量浓度分别为25,125,250μg/mL时,对单增李斯特菌生物膜形成的抑制率分别为18.83%,39.98%和83.27%,细菌总蛋白和胞外多糖明显减少;对单增李斯特菌侵染Caco-2细胞黏附率抑制率分别为44.41%,67.68%和85.28%。结论:3,4-二溴-2(5H)-呋喃酮在亚抑菌浓度下,对单增李斯特菌生物膜的形成以及黏附细胞均存在一定的调控作用,且随着抑制剂浓度的增加抑制效果更明显。     

Candida etchellsii产2(5)-乙基-4-羟基-5(2)-甲基-3(2H)-呋喃酮的影响因素

在埃切假丝酵母(Candida etchellsii)发酵过程中,通过盐度调控和氨基酸添加,强化目标产物HEMF(2(5)-乙基-4-羟基-5(2)-甲基-3(2H)-呋喃酮)的合成效率。分阶段调控发酵体系的盐度(初始阶段控制CaCl浓度为200 g/L,发酵40 h后提升至220 g/L),结合氨基酸添加(向发酵体系中添加丙氨酸、精氨酸和甘氨酸各1.67 g/L)。摇瓶结果表明:酵母C.etchellsii合成HEMF,其产量为110.74 mg/L。7 L发酵罐上罐验证,HEMF产量达到121.51 mg/L,相比空白(200 g/L CaCl浓度下且没有添加氨基酸)提高了21.2倍。分阶段盐度调控结合氨基酸添加策略显著强化了C.etchellsii对HEMF的合成。     

微生物发酵法制备4-羟基-2,5-二甲基-3[2H]-呋喃酮的研究进展

4-羟基-2,5-二甲基-3[2H]-呋喃酮(HDMF)是一种很好的食品调味剂,具有很高的商业价值.文中分析了微生物发酵法制备HDMF的优越性,总结了产生HDMF的菌种,论述了对其产生机理进行的探索,说明了目前存在的问题,并展望了运用现代生物技术手段改良菌种、构建幕因工程菌株、达到高产HDMF的研究前景.     

酱油中呋喃酮类物质的研究进展

酱油是我国一种传统的调味品,具有特殊的色、香、味,还具有一定生理活性.在酱油酿造过程中生成的4-羟基-2,5-二甲基-3(2H)-呋喃酮(HDMF)和4-羟基-2(5)-乙基-5(2)-甲基-3(2H)-呋喃酮(H EMF)是酱油酱香型风味物质的主体成分.不同原料及配比、接种方式和生产工艺的不同均会影响微生物的生长代谢...     

群体感应抑制剂3,4-二溴-2（5H）-呋喃酮对荧光假单胞菌生物膜形成的抑制作用

为了研究3,4-二溴-2（5H）-呋喃酮（3,4-dibromo-2（5H）-furanone,DF）对荧光假单胞菌生物膜形成的抑制作用。通过在24孔板和硅胶片上构建生物膜模型,CFU计数法测定DF对荧光假单胞菌的最低抑制浓度（Minimum Inhibitory Concentration,MIC）和最低杀菌浓度（Minimum Bacterial Concentration,MBC）以及生物膜生长曲线,在1倍MIC和5倍MIC的DF作用下的荧光假单胞菌生物膜形成率和细菌群集运动能力,并探讨DF对荧光假单胞菌总蛋白合成及多糖含量的影响。结果表明,DF对荧光假单胞菌作用的MIC和MBC值分别为12.5μg/m L和800μg/m L;在DF浓度为1 MIC和5 MIC时,作用于荧光假单胞菌24 h生物膜形成抑制率分别为20.59%±2.91%和99.54%±1.83%,并能明显抑制荧光假单胞菌的群集运动能力,干扰荧光假单胞菌群体感应（Quorum sensing,QS）系统而影响其总蛋白合成及多糖的含量,24 h时5 MIC的DF对荧光假单胞菌总蛋白和菌多糖合成量的抑制率分别为8.04%±0.37%和51.08%±2.71%。本研究对DF影响荧光假单胞菌生物膜形成的原因,DF对荧光假单胞菌生物膜形成的抑制作用及其对QS通路的干扰具有良好的理论和实践参考。      

基于群体感应的单增李斯特菌生物膜形成与控制研究进展

单增李斯特菌的生物膜结构可以赋予细菌对消毒剂更强的耐受性,这使得如何有效清除其生物膜成为了食品加工业的难题。群体感应与细菌生物膜的形成、毒力侵袭特性和应激响应等生理特性密切相关。因此,本文概述了单增李斯特菌生物膜的特性,重点从群体感应（呋喃糖基硼酸二酯系统和寡肽自诱导因子系统）角度阐述了单增李斯特菌生物膜的形成机制,并综述了当前控制单增李斯特菌生物膜形成的可行方法及植物提取物作为群体感应抑制剂的研究现状。以期为预防和控制单增李斯特菌生物膜的形成提供新思路。     

美拉德反应中间体2,3-二氢-3,5-二羟基-6-甲基-4(H)吡喃-4-酮的研究进展

2,3-二氢-3,5-二羟基-6-甲基-4(H)吡喃-4-酮(2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one, DDMP),是美拉德反应关键中间体之一,在美拉德反应产物调控中起到重要作用。DDMP属于烯醇酮类化合物,广泛存在于天然尤其是热加工食品,具有抗氧化、抗菌、心脏保护等作用。当前,随着对食品安全、风味和活性功能关注度的不断提升,学者对DDMP进行了广泛而深入的研究。该文基于近年来相关文献,对DDMP的存在、形成及降解、生物活性及感官特性等方面的研究进展进行全面系统的总结,旨在为DDMP在食品、医药、香料领域的基础和应用研究提供参考。     

2，6-二甲基-4-羟基苯甲醛的合成与反应历程研究

对传统的2,6-二甲基-4-羟基苯甲醛合成方法进行改进,确定最佳合成工艺条件:n(3,5-二甲基苯酚):n(Zn(CN)2):n,(AICl3)=1:0.7:1.8,以AlCl3升华品为催化剂,合成温度65℃,此时收率可达51.1%,较传统合成法提高了10.1%,纯度可达99.5%.     

新型甜味剂N-[3-(3-羟基-4-甲氧基苯基)丙基]-阿斯巴甜的制备研究

为了制备新型高倍二肽甜味剂,从甜味机理出发,通过钯碳催化和阿斯巴甜分子选择性催化加氢反应方法,以3-羟基-4-甲氧基苯甲醛和乙醛为原料,研究制备新型高倍甜味剂N-[3-(3班基-4-甲氧基苯基)丙基]-阿斯巴甜.结果表明,所得产物由于在阿斯巴甜分子上引入了疏水基团"-OCH3","-OH",甜度大大提高,约为蔗糖的24000倍.     

Stability of naturally occurring 2,5-dimethyl-4-hydroxy-3 [2H]-furanone derivatives

The stability, in aqueous buffer solutions at different pH values (pH?2.0–8.0, interval: 1.5?pH units), of 2,5-dimethyl-4-hydroxy-3[2H]-furanone (Furaneol, DMHF, 1), its methoxy derivative 2,5-dimethyl-4methoxy-3[2H]-furanone (methoxyfuraneol, mesifurane, DMMF, 2 and the glycosidically bound forms DMHF β-D-glucopyranoside 3 and DMHF 6′-O-malonyl-β-Dglucopyranoside 4 was investigated over a period of 32 days at 23?°C. Only slight decomposition of 2 and 3 was observed, whereas 1 and 4 were found to be unstable at all pH values. In addition, 3 and 4 were subjected to enzymatic hydrolysis. In contrast to the rapid hydrolysis of 3, the malonylated glycoside, 4, remained unaffected by enzymatic treatment with β-glucosidase (Emulsin). Using a pectinolytic enzyme preparation (Rohapect D5L; Röhm, Darmstadt, Germany) with esterase activities, hydrolysis of 4 was achieved.     

Stability of naturally occurring 2,5-dimethyl-4-hydroxy-3 [2H]-furanone derivatives

The stability, in aqueous buffer solutions at different pH values (pH 2.0–8.0, interval: 1.5 pH units), of 2,5-dimethyl-4-hydroxy-3[2H]-furanone (Furaneol, DMHF, 1), its methoxy derivative 2,5-dimethyl-4methoxy-3[2H]-furanone (methoxyfuraneol, mesifurane, DMMF, 2 and the glycosidically bound forms DMHF β-D-glucopyranoside 3 and DMHF 6′-O-malonyl-β-Dglucopyranoside 4 was investigated over a period of 32 days at 23 °C. Only slight decomposition of 2 and 3 was observed, whereas 1 and 4 were found to be unstable at all pH values. In addition, 3 and 4 were subjected to enzymatic hydrolysis. In contrast to the rapid hydrolysis of 3, the malonylated glycoside, 4, remained unaffected by enzymatic treatment with β-glucosidase (Emulsin). Using a pectinolytic enzyme preparation (Rohapect D5L; R?hm, Darmstadt, Germany) with esterase activities, hydrolysis of 4 was achieved. Received: 25 September 1996     

环境胁迫对屎肠球菌8-3 LuxS/AI-2群体感应系统的影响

以酸马奶酒中分离出的1 株高产信号分子AI-2（Autoinducer-2）的屎肠球菌（Enterococcus faecium）8-3为研究对象,通过改变菌株生长环境（pH值、温度、渗透压、营养条件）探究对菌株LuxS/AI-2群体感应系统的影响。采用生物学方法和实时荧光定量聚合酶链式反应法检测信号分子AI-2产量及相关基因luxS和pfs表达量的变化。结果表明：轻度酸性胁迫会诱导E. faecium 8-3信号分子AI-2的产生,碱性条件下菌体生长旺盛,菌体密度主要介导信号分子AI-2产生;在渗透压和低温胁迫时,E. faecium 8-3菌体密度和信号分子AI-2的产生同时受到抑制,菌体密度调控信号分子AI-2的产生;低6-82营养胁迫可以诱导E. faecium 8-3产信号分子AI-2。不同环境胁迫下E. faecium 8-3的luxS和pfs基因表达均有不同程度的变化,说明LuxS/AI-2群体感应系统参与菌株的抗逆过程。     

Amino acid-dependent formation pathways of 2-acetylfuran and 2,5-dimethyl-4-hydroxy-3[2H]-furanone in the Maillard reaction

The formation pathways of two furanoids, 2-acetylfuran and 2,5-dimethyl-4-hydroxy-3[2H]-furanone (DMHF) were studied by GC–MS in the Maillard-type model system based on glucose and selected amino acids. The reaction was performed in 0.01 M phosphate buffer by heating a 1:1 mixture of [¹³C6] glucose and [¹²C6] glucose with amino acid. There is only one major formation pathway for DMHF in which the glucose carbon skeleton stayed intact. Formation pathways for 2-acetylfuran were more complicated. They formed either from glucose or from glucose and glycine. In the presence of glycine, the [C-5] unit of glucose combined with formaldehyde from glycine leads to 2-acetylfuran. For other amino acids, either cyclisation of intact glucose or recombination of glucose fragments can lead to 2-acetylfuran formation. These results indicate a competitive trend in controlling Maillard reaction. Therefore, besides changing Miallard reaction impact factors (temperature, time, pH etc.), inhibiting or preventing the competitive reaction cascade may direct desired pathways of Maillard reaction.     

LuxS/AI-2群体感应系统对植物乳杆菌抵御环境胁迫的作用

LuxS/AI-2群体感应系统可介导乳酸菌种内和种间信号,其中自诱导因子-2(autoinducer-2,AI-2)对乳酸菌的益生菌活性(环境胁迫耐受、黏附和定植能力等)至关重要。然而,目前对于LuxS/AI-2群体感应系统在植物乳杆菌抵御多种环境胁迫中的调控作用仍有待系统研究。通过群体感应信号分子研究及实时荧光定量聚合酶链式反应,分析了环境胁迫下植物乳杆菌KLDS 1.0328信号分子AI-2产量及群体感应关键基因luxS和pfs的转录情况。结果表明:酸胁迫可诱导信号分子AI-2的产生,强酸及强碱胁迫下可显著促进luxS及pfs的转录(P<0.05)。低温25℃、高温50℃、质量分数6.0%NaCl及质量分数3.0% NaCl+3.0% KCl诱导的高渗透压胁迫均会显著抑制菌体的增殖和代谢产酸,并抑制信号分子AI-2的产生;25℃低温胁迫会上调luxS及pfs基因的转录。随着高渗胁迫程度的增强,luxS及pfs基因的转录水平均逐步上调。营养胁迫诱导植物乳杆菌KLDS 1.0328产生更多的信号分子AI-2;随营养胁迫程度的加剧,luxS的转录水平显著上调,在营养物质体积分数为20%时,luxS及pfs基因的转录均达到最高水平,而pfs基因的转录在营养物质被稀释至体积分数为40%~60%时被显著抑制(P<0.05)。研究结果表明,多种环境胁迫下LuxS/AI-2群体感应系统具有不同的变化规律,且在植物乳杆菌KLDS 1.0328的抗逆过程中发挥重要作用。     

L-Rhamnose: progenitor of 2,5-dimethyl-4-hydroxy-3 [2H]-furanone formation by Pichia capsulata?

 2,5-Dimethyl-4-hydroxy-3[2H]-furanone (Furaneol, 1), an important aroma constituent, was detected at concentrations of up to 2 mg/l after 4 days of growth of Pichia capsulata on casein peptone culture medium containing L-(+)-rhamnose (2). Blank samples without yeast contained no 1 after the incubation period. In parallel experiments five samples of 2 exhibiting different [¹³C] abundance were given to P. capsulata. The volatile compounds formed were isolated and analysed for their [¹³C]/[¹²C] ratios by on-line gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). A positive correlation between the isotopes in 1 and 2 was observed; thus, 2 served as the carbon source for 1. However, 1 was formed from a postulated intermediate of 2 generated during thermal sterilization, as 1 was neither detected after sterile filtration of the culture medium nor after separate thermal sterilization of the casein peptone and 2. This observation was confirmed by an experiment investigating the time course of the formation of 1. Received: 4 June 1996     

High Performance Liquid Chromatography of 2,5-Dimethyl-4-Hydroxy-3 (2H)-Furanone in Pineapple and Grapefruit Juices

A reversed-phase HPLC method was developed for rapid analysis of 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF), the compound responsible for the “burnt-pineapple” flavor in pineapple juices. A Zorbax ODS column was used with a mobile phase of 0.05M sodium acetate (pH 4.0)/methanol (70:30); detection was by UV at 290 nm. Sample clean up was accomplished by solid-phase extraction with C-18 Sep-Pak cartridges. DMHF contents ranged from 1.6 to 27.3 ppm from 10 fresh pineapple juices. Using this system, the production of DMHF was monitored in canned grapefruit juices during storage at varying temperatures.