使用核糖核酸盐从酵母核蛋白中分离核酸和蛋白质

酵母和微生物蛋白用于食品受到限制,其主要原因是由于含有大量核酸(8—25g/100g干蛋白)。本文研究了核糖核酸盐对核酸从酵母核蛋白分离的作用。各种盐对核酸分离的影响如下:Cl_3COONa=NaClO_4>NaBr>NaCl。使用0.5MCl_3ClONa或NaCl_4时核酸去除率达到80％。而使用NaCl和NaBr能达到10和25％。根据所给出的结果表明。在工业化生     

酵母单细胞蛋白絮凝分离的研究

本文提出了分离酵母单细胞蛋白的一种新方法——用絮凝沉降法分离酵母单细胞蛋白;研究了鞣酸+A对酵母细胞的絮凝作用。探讨鞣酸+A絮凝酵母细胞的机理;较为系统地研究了环境因素对鞣酸+A絮凝酵母细胞的影响;首次将质心映射优化法(CMO法)和响应面法(RSM法)结合起来,运用计算机优化了絮凝条件,并就鞣酸+A对酵母细胞的絮凝作用进行表征;通过对酵母细胞表面的X-射线能谱分析,证实金属离子Ca~(2+)、Cd~(2+)、Mn~(2+)和K~+参与了鞣酸+A对酵母细胞的絮凝作用。通过鞣酸+A絮凝酵母细胞的小试研究,可以认为采用絮凝沉降法分离酵母单细胞蛋白是可行的,且节能效果显著,具有较大的现实意义。     

一种快速高效提取酵母质粒的方法

质粒提取是遗传工程操作的重要步骤。酵母细胞壁坚韧,不易破壁,使酵母质粒提取变得非常困难。为了获得一种快速、简便、高效、稳定的提取酵母质粒的方法,利用琼脂糖凝胶电泳、核酸蛋白测定仪和PCR扩增等方法,对玻璃珠液氮法、蜗牛酶法和试剂盒法提取的酵母质粒,在产率、纯度和对后续实验的影响等方面进行了比较。结果表明,与另外两种方法比较,玻璃珠液氮法提取酵母质粒具有效率高、质量好、成本低、时间短、操作简单的优点,可作为实验室规模化提取酵母质粒的常用方法。     

核酸适配体—靶标复合物解离常数测定方法 研究进展

核酸适配体是通过体外指数富集配基系统进化技术筛选到的一小段单链DNA或RNA寡核苷酸片段,能够与靶标高亲和力、高选择性地结合。为了在实际检测中应用核酸适配体,必须深入了解核酸适配体—靶标的结合过程,如测定复合物的解离常数。本文综述了近年来有关核酸适配体—靶标复合物解离常数测定的方法。这些方法大致上分为两大类:一类是基于分离策略的测定方法,如透析法、超滤法、凝胶电泳法、毛细管电泳法和高效液相色谱法;另一类是基于均相策略的测定方法,如荧光强度法、荧光各向异性法、紫外可见分光光度法、圆二色谱法以及表面等离子体共振法等。本文对每种方法的原理、应用范围和特性进行了概括和比较,并对未来的发展趋势进行了展望。     

核酸酵母产品的开发和应用

核酸酵母生产是将单细胞蛋白和核糖核酸生产结合起来，它的产品为脱核酵母和核糖核酸。脱核酵母是一种蛋白质含量高达50％以上的单细胞蛋白，属优质饲料蛋白。核酸广泛应用于食品工业、医药工业和农业上。利用玉米淀粉为原料，采用综合高技术生物加工工艺，先生产酵母，再由酵母提取核酸，并通过单细胞蛋白生产技术消化生产过程中的废水，降低单细胞蛋白生产成本，综合经济效益和社会效益显著。     

多元线性回归设计优化微波辅助提取啤酒废酵母细胞RNA

为了开发利用啤酒在发酵过程产生的废酵母细胞,本实验以啤酒废酵母泥为原料,以酵母细胞中的核酸为研究对象,通过微波加热提取核酸的方法提取啤酒废酵母细胞中的核酸,探讨了微波功率、微波温度、微波时间、料液比、提取时间、提取温度等因素对产品提取率的影响,从而获得最佳提取条件。通过多元线性回归试验,结果表明最佳工艺参数为:微波功率700W、微波时间4min、浸提时间3.5h、浸提温度100℃,测得总核酸含量为10.920μg/ml。微波法与传统提取核酸的方法相比具有提取时间短、效率高等特点,大大降低了能量消耗,可应用于工业化大生产。     

酒石酸与铬配位影响因素的研究

根据反应液可见光谱的特征吸收峰位、峰值以及吸收半峰宽的变化,探讨了羟基、羧基解离度及铬配合物分子大小对酒石酸与铬配位的影响。结果表明：酒石酸分子中的羟基增强了其与铬的配位能力;适当增大酒石酸的羧基解离度、铬配合物的分子大小均有利于其与铬配位,但前者的影响程度大于后者;作为铬鞣蒙囿剂最好用酒石酸并在鞣制前期加入;酒石酸及其盐均可用于脱铬,用酒石酸需调pH值,而用其盐则不需调pH值;二者均可用于铬鞣革的漂洗,盐的效果会更好。     

酒石酸与铬配位影响因素的研究

根据反应液可见光谱的特征吸收峰位、峰值以及吸收半峰宽的变化,探讨了羟基、羧基解离度及铬配合物分子大小对酒石酸与铬配位的影响.结果表明:酒石酸分子中的羟基增强了其与铬的配位能力;适当增大酒石酸的羧基解离度、铬配合物的分子大小均有利于其与铬配位,但前者的影响程度大于后者;作为铬鞣蒙囿剂最好用酒石酸并在鞣制前期加入;酒石酸及其盐均可用于脱铬,用酒石酸需调pH值,而用其盐则不需调pH值;二者均可用于铬鞣革的漂洗,盐的效果会更好.     

高静压处理对芸豆分离蛋白的聚集行为研究

采用排阻色谱-多角度激光光散射-折光联用技术(SEC-MALLS-RI)研究高静压处理(HP)对芸豆分离蛋白分子量分布的影响规律,揭示HP导致KPI聚集-解离行为.根据Debye plot方法,计算出芸豆球蛋白的绝对分子量为161 kDa,200 MPa HP处理解离KPI的可溶性聚集物,而400和600 MPaHP处理诱导不溶性聚集物向可溶性聚集物转化,改善KPI的溶解度(PS).     

啤酒酵母中核苷酸的提取研究

对压榨啤酒酵母粉进行处理，采用盐热法提取核酸液，利用5’-磷酸二酯酶把核酸分解为4种核苷酸，按核苷酸的不同特性，用树脂对其进行分离，使4种核苷酸都能得到较好的分离。     

Ruminal fermentation in vivo as influenced by long-chain fatty acids

Responses of ruminal microbes to long-chain fatty acids in forms of free acids, calcium salts, or triglycerides were measured in trials with rumen cannulated heifers. Addition of fatty acids at 10% to a basal diet of 50% corn silage and 50% grain increased fat content 3 to 10 to 12%. Long-chain fatty acids with a high melting point (stearic acid) and calcium salts of long-chain fatty acids (vegetable fat and tallow) decreased acetate:propionate by about 20%. Long-chain fatty acids with a low melting point (oleic acid) and the triglyceride form of long-chain fatty acid (tallow) decreased acetate to propionate ratio by 50 to 60%. Even though they were not completely inert in the rumen, responses with the hard long-chain fatty acids (stearic acid) and with calcium salts of long-chain fatty acids confirm that these are efficacious for protecting ruminal microbes from adverse effects of fat. With calcium salts of long-chain fatty acids, dietary buffers may be needed to maintain ruminal pH so that dissociation of salts does not occur. Long-chain fatty acid supplementation at 10% of the diet is probably more than the amount needed to optimize productivity and health. With most diets, 6 to 8% supplemental long-chain fatty acid is probably sufficient.     

酵母核酸对肉仔鸡生长性能和血液生化指标的影响

在肉鸡日粮中添加酵母核酸,研究酵母核酸对肉鸡生长性能和部分血液指标的影响。125只1日龄艾维茵肉鸡,随机分为5组,每组5个重复,每个重复5只。对照组饲喂基础日粮,试验组分别在基础日粮的基础上添加0.1%、0.2%、0.3%、0.4%的酵母核酸。试验期4周,在第2周末和试验结束时,分别测定生长性能,并采取血样,测定血清生化指标。结果表明:添加不同水平的核酸能显著提高后2周的日增重,而在前2周,虽然各试验组均比对照组的日增重有所提高,但只有添加0.3%,0.4%的核酸对肉鸡的日增重的影响较显著(P<0.05);添加酵母核酸后料肉比降低,前2周差异不显著(P>0.05),后2周添加0.3%、0.4%酵母核酸组同对照组比差异显著(P<0.05)。添加酵母核酸能提高两个阶段肌肉中粗蛋白的含量,但前2周,各处理组间差异不显著(P>0.05),后2周,添加0.3%核酸组蛋白质的含量有明显的提高(P<0.05)。前2周,添加酵母核酸对肉鸡血清尿酸、血糖、总胆固醇、甘油三酯、高密度胆固醇以及低密度胆固醇的影响均不显著(P>0.05);后2周,添加酵母核酸对肉鸡血清尿酸、血糖和高密度胆固醇的影响均不显著(P>0.05),而添加0.2%酵母核酸组能显著提高血清胆固醇、甘油三酯和低密度胆固醇的含量(P<0.05)。     

从海鱼鱼白中提取核酸

对地产海鱼加工下脚料鱼白中核酸含量测定、提取方法、产品纯度测定和组分鉴定方法进行了研究.结果显示在样品预处理过程中,低温抽提法比索氏抽提器法造成核酸损失要小.核酸粗产品收率为6.72％时,核酸总质量分数为2.30％.     

Effect of salts on the solubility of phenolic compounds: experimental measurements and modelling

Phenolic compounds can be found in industrial or agricultural waste, such as waste water from olive mills. Because of the environmental problem caused by this residue from olive oil production, the aim of this work was to model the effect of salts on the solubility of four phenolic compounds. For this purpose, the solubilities of gallic acid, protocatechuic acid, vanillic acid and vanillin have been measured in various chloride solutions at constant temperature. The Clegg–Simonson–Pitzer activity coefficient, together with the dissociation constant obtained from the literature, has been used to represent the equilibrium solid‐liquid data. Good agreement (3.4%) between the experimental and calculated values for solubility was obtained. Copyright © 2007 Society of Chemical Industry     

产朊假丝酵母核酸高产株的选育及其发酵性能研究

为了获得一株发酵性能优良的高核酸酵母,以产朊假丝酵母(Candida utilis)CL1501为出发菌株,采用紫外-亚硝基胍复合诱变,筛选获得一株高核酸含量的突变株CL15013,经测定其核酸含量占菌体干质量的16.8%,高于出发菌47.8%。对比研究其流加及分批培养工艺,流加培养细胞收获量为16.9 g/L,比分批培养提高94.3%;正交试验设计优化流加培养条件后,CL15013的收获量达21.3 g/L,比分批培养提高144.8%,具有良好的生产应用潜力。     

The utility of a fungal bibonuclease for reducing the nucleic acid content of permeabilized yeast cells

The main drawback of yeast biomass as a source of protein for human consumption is its high nucleic acid content. The present study deals with the development of a process for reducing the nucleic acid content of strains of Saccharomyces cerevisiae, Candida utilis, C.tropicalis and C.lipolytica by treating with an RNase of Aspergillus candidus strain Ml6a. The cells were permeabilised either by heat‐treatment at 95°C for 5 min. or by treatment with chloroform for 6h followed by a heat treatment at 65°C for 3 min. The former pretreatment was sufficient for C. utilis and C.tropicalis strains whereas S.cerevisiae required the latter treatment. The optimum conditions for the enzymatic treatment were a pH of 4.5–5.0, temperature of 45–55°C, incubation period of 60–90 min and an enzyme to cell ratio of 1:6,000 (w/v). Crude enzyme preparations showed a better activity than the pure enzyme. Under optimal conditions 80–85% of the total nucleic acid could be removed from yeast cells by the enzymatic treatment without any significant concomitant loss of protein.     

Effects of Phosphorylation on Emulsifying and Foaming Properties and Digestibility of Yeast Protein

Phosphorylated yeast protein (PYP) (73% protein, < 3% nucleic acid) was prepared from yeast nucleoprotein by chemical phosphorylation using phosphorus oxychloride. The emulsifying activity index (EAI) of PYP was low at pH 5 but exceeded that of BSA at pH 7.0. The emulsions were stable after heating to 90°C for 60 min. The stability of foams made with PYP increased from t_1/2 1.5 to 13 min as pH was increased from 5 to 8. Foams made from PYP were weak but increased with protein from 0.1 to 0.5 mg/100 mL. The PYP were easily digested by pepsin and pancreatin indicating negligible inhibition by phosphorylation.     

The quantitative determination of protein content in milk by means of ultraviolet spectrophotometry. 2. The suitability of the difference of absorbance at 235 and 280 nm for quantitative milk protein analysis

The protein content of skimmed milk was determined by measuring the absorbance at 235 and 280 nm after dilution with alkylpolyglycolethersulphate solution. The difference of absorbance A235-A280 shows a high correlation to the values of KJELDAHL nitrogen analysis (r = 0.99). The protein content of casein and milkserum solutions could be determined in the same way. The method has the advantage, that their results are approximately independent of the amino acid composition of proteins, the content of nucleic acids, salts, lactose and non protein nitrogen. Both absorbances are obtainable from one solution. The dependence of the absorbance difference from the age of solution, the age of milk and from the temperature was investigated as well as the influence of preservatives.     

氯化盐处理对绿豆芽菜植酸降解的影响

为降低绿豆芽菜中抗营养物质植酸含量,探究氯化盐对绿豆芽菜植酸降解的影响,研究了KCl、NaCl和CaCl2处理下绿豆芽菜的长势、植酸酶活性及植酸含量的变化,筛选了具有降植酸效果的氯化盐并优化了浓度组合。结果发现,NaCl和CaCl2能够促进植酸降解同时促进绿豆芽菜生长;单因素试验结果表明,1.6 mmol/L NaCl和6 mmol/L CaCl2降植酸效果最佳,且NaCl和CaCl2促进植酸降解作用有叠加效应。响应面法优化得到NaCl、CaCl2浓度分别为1.68 mmol/L和6.40 mmol/L时,植酸含量降低至8.04 μg/株,为对照的10.84%。     

利用高压脉冲电场诱导啤酒酵母细胞释放蛋白质与核酸

研究了相对条件对高压脉冲电场(HPEF)技术破壁啤酒酵母细胞、提取酵母细胞中的蛋白质和核酸效果的影响。结果表明,啤酒酵母悬浮液经高压脉冲(频率500 ppa,场强25 kV/cm,处理时间1152μs)作用,再经搅拌(50℃下,6 h)处理后,蛋白质和核酸的提取率分别达到69.90%和82.84%。实验表明,利用高压脉冲电场破壁啤酒酵母细胞,并结合搅拌的方式提取蛋白质和核酸,蛋白质和核酸的提取率均高于单独使用高压脉冲电场或单独使用搅拌进行破壁提取的提取率。