一种高效干冻研磨破碎酵母细胞的方法

[目的]建立简便有效的破碎酵母细胞的方法。[方法]离心收集酵母细胞,将培养液洗涤干净后直接将酵母细胞和研钵预冷至-20℃,然后在冰冻状态将酵母细胞置于研钵中研磨,在相差显微镜下观察酵母细胞的形态,计算细胞破碎效率,并提取破碎酵母的染色体DNA和蛋白质。[结果]镜下观察研磨后酵母完整细胞数明显减少,并有大量细胞碎片。计数得出研磨1、2、3、4、6、8、10min后破碎细胞的百分数为13.7%、30.1%、52.0%、85.1%、93.4%、94.6%、95.9%,0.1g酵母细胞研磨后抽提到的DNA和蛋白质的量分别为20μg和2.928mg。常规条件干冻酵母细胞直接研磨获得良好的破碎效果,破碎效率达95.9%。[结论]该研究建立了一种简便、高效而又经济的裂解酵母细胞的方法。     

酵母培养物对鹌鹑生长性能、免疫器官指数及肠道菌群的影响

[目的]为了研究酵母培养物对鹌鹑生长性能、免疫功能和肠道菌群的影响。[方法]试验选取1日龄朝鲜龙城系鹌鹑720羽,随机分4个处理组,每组6个重复,每个重复30羽。对照组饲喂基础日粮,试验Ⅰ组、Ⅱ组和Ⅲ组分别在基础日粮的基础上添加0.1%、0.15%和0.2%的酵母培养物,试验期42d。[结果]结果表明：试验Ⅱ组和Ⅲ组均能显著提高鹌鹑1-21d、22-42d和1-42d平均日增重,降低料重比。显著提高21d和42d鹌鹑法氏囊指数和42d鹌鹑胸腺指数、脾脏指数。试验Ⅰ组、Ⅱ组和Ⅲ组均能显著降低21d鹌鹑盲肠中大肠杆菌、沙门氏菌数量,试验Ⅱ组和Ⅲ组能显著增加乳酸杆菌数量,且试验Ⅰ组和Ⅲ组组间差异亦显著;试验Ⅰ组、Ⅱ组和Ⅲ组均能显著降低42d鹌鹑盲肠中大肠杆菌、沙门氏菌数量,显著提高乳酸杆菌数量,试验Ⅰ组和Ⅲ组组间差异均显著。[结论]说明酵母培养物提高鹌鹑的生产性能和免疫功能,改善肠道的菌群结构。适宜添加量为0.15%。     

不同絮凝剂对光合细菌沉降与净水能力的影响

光合细菌产品为液态产品,运输成本较高,该研究初步筛选可用于光合细菌菌液沉降浓缩的絮凝剂,为光合细菌菌液产品的浓缩工艺提供参考。分别以聚合氯化铝(PAC)、聚丙烯酰胺阳离子型(CPAM)和阴离子型(APAM)、酵母4种常用絮凝剂对光合细菌菌液进行沉降,测定絮凝率;选取最佳的絮凝剂,分析经沉降浓缩的菌液的菌体活性,及其对水体中化学需氧量(COD)、氨氮和亚硝酸盐去除率。4种絮凝剂中PAC对光合细菌的絮凝沉降效果最佳,CPAM次之,酵母沉降速度较慢,APAM沉降效果最差;以PAC沉降1 h得到的浓缩光合细菌菌液的菌体活性强,PAC添加浓度在500 mg/L时,浓缩菌液的活菌浓度最高,达到浓缩前的19.9倍;随着PAC添加浓度的升高,浓缩菌液的活菌浓度逐渐下降;PAC沉降浓缩菌液对COD和亚硝酸盐的去除效果显著增强,5 d COD去除率最高达69.53%,2 d亚硝酸盐去除率均为100%;浓缩菌液对氨氮的去除率显著高于非浓缩菌液。PAC对光合细菌的沉降浓缩效果最佳,沉降浓缩后菌液的水质净化能力显著提高;综合考虑,PAC添加浓度以500 mg/L为宜,沉降浓缩时间为1 h。     

不同培养基的酵母发酵液对细菌纤维素产量的影响

为了提高细菌纤维素(BC)产量,研究4种酵母菌在NCW、PDB、YPD和BS等4种不同培养基中的发酵液对Gluconacetobacter europaeus Y9 BC产量的影响,并与新鲜椰子水和自然发酵椰子水发酵生产BC的产量进行对比。结果表明:在YPD培养基制成的4种酵母菌发酵液中BC产量都是最高的,其中活性干酵母贝酵母、面包酵母和自行分离筛选的野生酵母威克克鲁维酵母、热带假丝酵母生产的BC产量分别为6.91、5.53、6.15、4.67 g/L,都显著高于以新鲜椰子水发酵合成的BC产量,贝酵母和威克克鲁维酵母在不同培养基中对BC产量影响不同,可能高于或者是接近自然发酵椰子水中的BC产量。推测酵母菌发酵液促进BC合成的原因不仅由于产生了合适浓度的乙醇,应该还与酵母菌产生了其他代谢产物,并且提供了良好的缓冲能力等有关。另一方面,筛自自然发酵椰子水的、野生的威克克鲁维酵母在任何培养基中培养后BC产量都较高,推测该菌株可能是新鲜椰子水经自然发酵后能使BC产量大幅度提高的重要贡献菌种之一。     

酵母发酵饲料对瘤胃菌群数量及多样性的影响

本试验研究日粮中添加酵母发酵饲料对蒙古绵羊瘤胃菌群数量及多样性的影响.选用10只安装永久性瘤胃瘘管且体重约40 kg的14月龄蒙古羯羊,分为对照组和试验组,每组各5只.对照组饲喂基础日粮,试验组饲喂基础日粮+酵母发酵饲料(13.37％).预试期15 d,正试期5 d.于正试期晨饲后0、3、6、9、12 h依次采集瘤胃液...     

Rubisco小亚基前体蛋白preSSU的互作蛋白分析

由核基因编码的叶绿体前体蛋白能否正确定向和转运到叶绿体，对叶绿体的功能十分重要。采用酵母双杂交方法，筛选豌豆的cDNA表达文库，分析检测与Rubisco小亚基前体蛋白（preSSU）相互作用并参与其调控的蛋白。结果表明，共有6种不同类型的蛋白与preSSU互作，分别为组氨酸蛋白激酶基因、转运蛋白复合体、转录和翻译相关蛋白及复合体、信号传导相关基因和光合合成相关基因。通过与相关蛋白的相互作用，preSSU也许参与了植物抗逆信号传导系统，并在植物的生长发育、成熟和衰老过程中起重要作用。     

Influence of yeast extract and casein hydrolysate on callus multiplication and somatic embryogenesis of date palm (Phoenix dactylifera L.)

Complex organic additives are known to improve growth and differentiation of in vitro plant cultures. The present investigation was conducted to determine the effect of various concentrations of yeast extract (YE) and casein hydrolysate (CH) on callus growth and somatic embryogenesis in date palm cultivar Nabout Saif. Callus induced from shoot tip explants was grown on callus multiplication medium supplemented with either YE or CH at 0.0, 0.1, 0.25, 0.5, and 1 g l⁻¹. To induce somatic embryogenesis, callus was transferred to a hormone-free medium containing the corresponding concentration of additives. The results have shown that callus weight and the number of somatic embryos were directly proportional to increases in the concentration of organic additives tested. Callus growth was best achieved when 1 g l⁻¹ of either YE or CH was added to the culture medium. At this concentration of YE, callus growth was double that of the control medium. On CH-containing media growth was 2.3 times that of the control. This indicates that CH is more effective in enhancing callus growth. However, YE was more effective in enhancing somatic embryogenesis. The data show that the best somatic embryo formation was obtained on either 1 g l⁻¹ YE or 0.5 g l⁻¹ CH which produced 45 and 30 embryos per culture, respectively, as compared to 20 embryos produced in the control treatment. Resultant somatic embryos successfully rooted and regenerated plantlets which exhibited normal growth in the greenhouse. Enhanced plant regeneration, an essential criterion for commercial micropropagation, was achieved.     

Comparison of Different MARs(Matrix Attachment Regions)Effect on Transgene Expression

Three MARs(matrix attachment regions)fragments were cloned from tobacco (Nicotiana tabacum)(MAR1),yeast(Saccharomyces cerevisiae) (MAR3)and kidney bean(Phaseolus vulgaris) (MAR5)which ranged 984,822 and 782 bp,respectively.Sequence analysis showed that all the fragments had fairly high A/T content (73,62 and 75%,respectively),harbored different number and different type of some characteristic motifs of MARs,such as A-box and T-box,etc.The results of in vitro binding assay showed that the three MARs fragments derived from different organisms could bind specifically to the matrix extracted from the tobacco nuclei with different strength,which also demonstrated that these MARs fragments are functionally conserved during evolution.By using these MARs fragments to flank the β-glucuronidase (GUS) reporter gene and bialaphos resistance(bar) selectable marker gene,and then introducing the resulting plant expression vectors containing MARs-uidA-barMARs into tobacco through Agrobacteriummediated procedures,the effects of MARs sequences on the expression of transgenes in tobacco were investigated and compared.The GUS activity in individual transformants showed that,comparing to the controls without additional MARs,the overall transgene expression level in transformants with MARs had been greatly increased while the variations in transgene expression among transformants were decreased in different degrees.In accordance with the results of sequence analysis and in vitro binding assay in which MAR1 fragment showed the strongest binding strength,this MARs fragment also showed the greatest effect in increasing transgene overall expression level.     

缺铁条件下酵母中铁转运转录水平的研究进展

铁作为生物体内重要元素,在很多细胞功能以及生化过程中具有重要作用。尽管多数土壤中铁含量较为丰富,但在碱性或中性土壤中可以吸收利用的可溶性铁量却无法满足植物需要。在这种情况下所导致的缺铁胁迫不利于植物生长发育。本文从铁吸收系统的激活、胞内铁源的启动和铁相关代谢活动的调控三个方面阐述了酵母细胞中铁转运转录水平上的研究现状,最后展望了其发展前景。     

活性酵母在养猪生产中的应用研究

活性酵母作为一种天然、健康的微生态活菌制剂,在提高母猪生产性能、降低仔猪腹泻率、提高机体抵抗力等方面有着十分明显的功效.因此,活性酵母的研发及应用日益受到人们的重视.笔者就活性酵母的生物学特性、作用机理、在养猪业的应用及发展前景等方面进行详细的阐述,以提高经济效益,促进养殖业健康稳定发展.