肉桂醛对HL－60细胞的生长抑制及诱导凋亡作用研究

目的：探讨肉桂醛对HL-60细胞的增殖及凋亡的影响。方法：采用台盼蓝细胞计数和四甲基偶氮唑蓝(MTT)法研究肉桂醛对HL-60细胞增殖的抑制作用;采用流失细胞仪(FCM)、荧光显微镜(FM)、扫描电镜(SEM)以及透射电镜(TEM)探讨肉桂醛对HL-60细胞的诱导凋亡作用。结果：台盼蓝细胞计数和MTT法结果表明：肉桂醛对HL-60细胞的增殖有明显抑制作用,抑制作用与肉桂醛质量浓度及作用时间呈依赖关系,其半数致死质量浓度为34.87μg/mL;流式细胞仪检测结果表明：肉桂醛(终质量浓度20μg/mL)作用16h后,HL-60细胞早期凋亡比例为32.6%;该组细胞在荧光显微镜、扫描电镜以及透射电镜观察下均呈现早期凋亡特征。结论：肉桂醛能抑制HL-60细胞增殖并促进其凋亡。     

甲酸对酿酒酵母的细胞毒性

研究甲酸对酿酒酵母(Saccharomyces cerevisiae)GGSF16的毒害作用,测定不同质量浓度甲酸对酿酒酵母生长代谢的影响,结果表明,甲酸质量浓度为1.8 g/L时能够明显抑制酵母细胞的生长和降低乙醇产量,延长细胞发酵周期;酵母细胞外的核酸、蛋白质和丙二醛含量分别是对照组的1.4、1.67倍和5.3倍,...     

丙烯酰胺诱导酿酒酵母的抗氧化降解动力学研究

目的 研究丙烯酰胺处理酿酒酵母的抗氧化降解动力学。方法 以酿酒酵母为模型, 测定丙烯酰胺对酿酒酵母的生长影响及抗氧化指标。结果 丙烯酰胺对酿酒酵母的生长有抑制作用, 且呈剂量依赖性。与对照组相比, 大部分丙烯酰胺处理组的丙二醛(malondialdehyde, MDA)含量、谷胱甘肽(glutathione, GSH)含量、总超氧化物歧化酶(total superoxide dismutase, T-SOD)活力增加, 总抗氧化能力(total antioxidant capacity, T-AOC)降低, 且MDA含量、T-AOC的变化符合动力学方程。结论 在培养前期, 处理组各抗氧化指标的波动比对照组大, 这表明丙烯酰胺对酿酒酵母具有氧化损伤, 且在培养前期较为明显, 这可能与丙烯酰胺的半衰期及酿酒酵母自身抗氧化防御系统有关。     

肉桂醛微胶囊的制备工艺

研究了以阿拉伯树胶和麦芽糊精为壁材 ,喷雾干燥法制备微胶囊化肉桂醛的工艺条件 .探讨了壁材组成、乳化剂用量、固形物质量分数、芯壁比、进风温度、进料速度、喷射压力等对微胶囊化效果的影响 .经过正交试验 ,确定了最佳工艺条件 .实验结果表明 ,阿拉伯胶和麦芽糊精的最佳质量配比为 1∶1,蒸馏单甘酯的用量为 0 .4 g/dL ,固形物质量分数为 4 0 % ,芯材与壁材的配比为 1mL∶10 g ,肉桂醛微胶囊化的最佳喷雾干燥条件为进风温度 2 2 5℃ ,进料流量 2 10mL/h ,喷射压力0 .18MPa .实验还表明 ,肉桂醛微胶囊产品有一定的缓释抑菌效果 .     

肉桂醛抑菌作用的研究进展

肉桂醛是肉桂精油的主要成分,常被用作食用香料,同时具有良好的抑菌活性。综述肉桂醛对细菌和真菌的抑制作用,分析其作用机理,并对肉桂醛衍生物和肉桂醛微乳抑菌的前景进行了展望。     

肉桂醛添加方式对乳清浓缩蛋白凝胶特性的影响

利用乳液和微胶囊的包载改善肉桂醛的亲水性,并将其添加至浓缩乳清蛋白溶液中,利用热诱导形成乳清浓缩蛋白凝胶,表征凝胶的流变特性、持水性、质构及微观结构,探究肉桂醛添加方式对所得凝胶特性的影响.结果表明,添加肉桂醛后,蛋白质凝胶的持水力显著增加.以乳液形式添加时,肉桂醛含量与凝胶的黏弹性、持水力、质构特性和网络结构的致密性...     

肉桂醛缓释微胶囊的制备研究

研究了以阿拉伯树胶和麦芽糊精为壁材，喷雾干燥法制备微胶囊化肉桂醛的工艺条件。探讨了壁材组成、乳化剂用量、固形物浓度、芯壁比、进风温度、进料速度、喷射压力等对微胶囊化效果的影响。经过正交试验，确定了最佳工艺条件。     

葡萄酒酿酒酵母选育与非酿酒酵母混菌发酵研究进展

葡萄酒有着悠久的文化历史,营养全面,口味独特,成为人们餐桌上不可或缺的一种酒精饮料。随着消费人群的日益增多,面对不同的消费群体需要不同风味的葡萄酒来满足需要,原材料葡萄种类、酿酒酵母、酿造工艺都是影响葡萄酒风味的重要因素。随着科技的进步,酿酒酵母得到越来越多人的重视,非酿酒酵母产香气的研究也越来越多。本文综述了目前对酿酒酵母的选育方法和鉴定手段,非酿酒酵母对于葡萄酒产香的部分研究,以期对生产更多独特风味的葡萄酒做出理论上的贡献。     

β-1,3-1,4-葡聚糖酶在工业酿酒酵母表面的诱导展示表达研究

基于絮凝素FLO1基因片段为锚定序列,构建以诱导型GAL1启动子介导的表达载体YEP-GMPFAK,并实现以半乳糖为诱导剂,β-1,3-1,4-葡聚糖酶在酿酒酵母表面的展示表达。酵母转化子发酵实验表明,在pH6.0、50℃培养条件下,经2%半乳糖诱导24 h,表面展示酶活达到最大值322.83 U/g细胞干重。酶学性质测定表明,展示表达的β-1,3-1,4-葡聚糖酶具有良好的热稳定性。     

基于分子动力学模拟的青稞直链淀粉-肉桂醛复合物形成机制研究

采用分子动力学模拟技术对青稞直链淀粉-肉桂醛复合物复合前后的构象进行模拟,并对青稞直链淀粉及其复合物的均方根偏差、旋转半径、氢键数、相互作用势能、溶剂可及表面积变化差异进行比较分析;采用主成分分析法(PCA)绘制青稞直链淀粉-肉桂醛体系不同构象的自由能曲面图,并得出该复合物的结构。结果表明：在复合物形成过程中,青稞直链淀粉与肉桂醛间氢键个数在60 ns时最多,复合物旋转半径在30 ns时达到最大;与青稞直链淀粉相比,青稞直链淀粉-肉桂醛复合物中的范德华势能明显高于自身的氢键势能,均方根偏差更大,且溶剂可及表面积下降幅度大;青稞直链淀粉-肉桂醛复合物的自由能最低区域显示青稞直链淀粉分子和肉桂醛分子分别由各自独立状态复合为整体球状包合物;青稞直链淀粉与肉桂醛复合物结构是由2条淀粉链将肉桂醛分子紧密包裹形成的1个稳定球状结构。     

Formation of Volatile Sulfur-Containing Compounds by Saccharomyces cerevisiae in Soymilk Supplemented with L-methionine

The formation of volatile sulfur-containing flavor compounds from L-methionine catabolism by Saccharomyces cerevisiae EC-1118 was investigated in soymilk supplemented with this sulfur-containing amino acid with a focus on methionol (3-methylthio-1-propanol). Methionol produced from L-methionine metabolism of yeast in soymilk was extracted by solid-phase microextraction (SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). The effects of time (0 – 72 h), L-methionine concentration (0.05–0.20%), yeast extract concentration (0.00–0.30%), initial medium pH (4.5–6.9), and temperature (25–34°C) on the production of methionol were investigated. One-liter scale-up fermentation of soymilk by Saccharomyces cerevisiae EC-1118 was conducted for 48 h under static conditions with 0.15% of L-methionine, 0.10% of yeast extract, initial medium pH of 5.5, and temperature of 25°C, yielding 190 ppm of methionol. GC-olfactometry dilution analysis was conducted on extracts of the fermented soymilk, and no single compound was found to account for the overall odor perception. Methional (3-methylthio-1-propanal) and methionol were determined to be most potent odor-active compounds in the fermented soymilk. The fermented soy milk may serve as a complex sulfur flavor concentrate for applications in foods such as fermented soy products, enzyme-modified, and imitation cheeses.     

酿酒酵母发酵生产谷胱甘肽的研究

以诱变获得的酿酒酵母突变株YF(ZnCl2r,Ethr)为试验菌株,通过摇瓶发酵、发酵罐补料分批发酵,对突变株发酵生产谷胱甘肽进行研究.确定发酵罐分批发酵的最佳培养条件为:温度30℃,pH 6.0,接种量为20%,搅拌转速为150 r/min,通气量为250 L/h.在补料分批操作方式下,分别考察了摇瓶培养、发酵罐培养...     

Selectable marker replacement in Saccharomyces cerevisiae

Selectable markers integrated by the ‘gamma’ deletion method (Sikorski and Hieter, 1989) can be efficiently replaced in vivo with other markers by transformation with homologous plasmids. Transformation frequencies in experiments designed to replace original selectable markers with an alternate marker were high and molecular analysis confirmed that all transformants that exhibited the expected phenotypes (loss of the original prototrophy and gain of the alternate prototrophy) resulted from homologous recombination between plasmid sequences at the target locus. This technique involves no plasmid construction and greatly facilitates the generation of yeast cells containing multiple gene disruptions.     

Saccharomyces cervisiae在食品发酵工业中的研究进展

从基础理论和应用技术等方面综述了国内外对酿酒酵母(Saccharomyces cervisiae)研究进展及其在食品发酵工业中的最新研究成果。     

Bioconversion of heptanal to heptanol by Saccharomyces cerevisiae

Saccharomyces cerevisiae is widely known for its catalytic activity on substrates such as aldehyde and ketone. Interestingly, the activity of S. cerevisiae on heptanal (C₆H₁₃CHO), in spite of its being a very common aldehyde, has not been explored. The main objective of this study was therefore to investigate the bioconversion of heptanal, using a strain of the yeast S. cerevisiae. Bioconversion parameters such as incubation period, pH, concentration of substrate, yeast and maltose were also optimized. The study revealed heptanol as the major product. The optimum conditions for biotransformation were found to be: 3 days incubation; pH 7.0; heptanal concentration 0.15 ml/100 ml medium; and S. cerevisiae concentration of 0.15 g/100 ml medium. Reduction in maltose content (to 0.3 g maltose/100 ml medium) showed increased conversion of heptanal. Heptanoic acid and 2‐hydroxyheptanoic acid were obtained as two minor co‐products. The overall study showed that S. cerevisiae converted heptanal to heptanol by a yield of 68.9 ± 1.1% w/w under optimum conditions. Copyright © 2010 John Wiley & Sons, Ltd.     

Exclusion of Saccharomyces kudriavzevii from a wine model system mediated by Saccharomyces cerevisiae

This study investigated the competition and potential hybrid generation between the species Saccharomyces cerevisiae and S. kudriavzevii in a wine-model environment. Our main goal was to understand why S. kudriavzevii has not been found in wine fermentations whilst their hybrids are present. Auxotrophic mutants (Ura(-) and Lys(-)) were used to favour the selection of hybrids and to specifically differentiate the two species in mixed fermentations carried out at different temperatures (17 °C, 24 °C and 31 °C). Both yeasts showed a reduction in their maximum specific growth rates in mixed fermentations, indicating a clear antagonistic effect between the two microorganisms. Temperature played an important role in this competition. In this way, S. kudriavzevii was less affected at 17 °C, but S. cerevisiae was clearly the best competitor at 31 °C, preventing the growth of S. kudriavzevii. Population levels of S. kudriavzevii always significantly decreased in the presence of S. cerevisiae. Ethanol was measured throughout the fermentations and in all cases S. kudriavzevii growth was arrested when ethanol levels were < 5 g/l, indicating that this compound did not influence the competitive exclusion of S. kudriavzevii. Killer factors were also discarded due to the K(-) R(-) phenotype of both strains. Finally, no prototrophic interspecific hybrids were isolated in small-scale fermentations at any temperature assayed. Our results show that the lack of competitiveness exhibited by S. kudriavzevii, especially at high temperatures, explains the absence of this species in wine fermentations, suggesting that natural S. cerevisiae × S. kudriavzevii hybrids most likely originated in wild environments rather than in industrial fermentations.     

Saccharomyces cerevisiae SCY1发酵kefir的工艺研究

本文采用Saccharomyces cerevisiaeSCY1和乳酸菌混合发酵牛乳制备kefir,分别研究了接种量、灭菌条件、发酵温度和加糖量对kefir风味的影响,最终确定最佳工艺条件为:XPL-1接种量为0.0400g/L,SCY1接种量为103个/mL;灭菌条件为80~85℃下灭菌10min;发酵温度为32℃;加糖量为4%。通过此工艺条件制备的kefir,具有独特的风味和较高的营养价值。     

酿酒酵母生产谷胱甘肽的培养条件的研究

本实验对酿酒酵母(Saccharomyces cerevisiae)CS10515产谷胱甘肽的培养条件进行了初步研究,确定了其最佳培养基组成为:葡萄糖为5%、酵母膏1.2%、硫酸铵0.6%、硫酸镁0.02%、磷酸二氢钾0.1%;当发酵液初始pH为6.0、装液量50%～60%、振荡速度300r/min时,经过24h振荡培养后,谷胱甘肽的产量为90.20mg/L。