从啤酒废酵母中提取海藻糖的工艺研究及效益分析

以啤酒废酵母为原料,水为提取剂,利用煮沸的方法提取海藻糖,探讨了提取时间及料液浓度对海藻糖得率的影响。综合海藻糖的产量及成本,确定其最佳条件为:煮沸1 h,料液质量浓度为70 g/L,海藻糖的得率为9.069 mg/g湿酵母。提取物样品经红外光谱定性检验纯度较高。初步分析了年产10×104 t的啤酒厂从废酵母中提取海藻糖所带来的经济效益,认为比单纯烘干作为饲料更有市场前景。     

玉米海藻糖含量测定及其合成酶（TPS）基因序列分析

自然界生物体内广泛存在着海藻糖。海藻糖不仅能在正常情况下为生物体新陈代谢提供能量贮备,更能在干旱、高热、低温等逆境胁迫下通过大量积累来帮助生物体抵御逆境伤害。因此,对海藻糖积累及其合成途径关键酶类的研究已越来越受到人们关注。本研究以垫状卷柏（Selaginella pulvinata（Hook.et Grev）Maxi...     

Different strategies for salt tolerance in determined and indeterminate nodules of Lotus japonicus and Medicago truncatula

In this study, we examine how indeterminate and determined nitrogen-fixing root nodules of model legumes Lotus japonicus and Medicago truncatula adapt their non-structural carbohydrate pool during salt stress, with particular emphasis on trehalose, a compatible solute abundant in nodules of some legumes. M. truncatula and L. japonicus plants were inoculated with Sinorhizobium meliloti and Mesorhizobium loti, respectively, and the effect of 50 mM sodium chloride (NaCl) added to the nutrient solution was studied in a time-course experiment. Sucrose and pinitol were the predominant carbohydrates in nodules of both legumes, contributing to osmoprotection in nodules of L. japonicus under salt stress. Trehalose concentration increased under salt stress in L. japonicus nodules; however, compared with sucrose and pinitol, its concentration was too low to contribute efficiently to osmoregulation. By contrast, proline showed a dramatic increase in nodules and leaves of M. truncatula under salt stress, contributing to osmotic adjustment in this species. Results found in this study showed different mechanisms for salt tolerance in determined and indeterminate nodules of model legumes L. japonicus and M. truncatula that might be a general feature in the mentioned different types of nodules.     

大肠杆菌otsA基因的克隆和转化本生烟草

海藻糖是一类重要的渗透调节剂,可以提高植物抵抗多种非生物胁迫的能力。6-磷酸海藻糖合成酶(TPS)是海藻糖生物合成的关键酶,在大肠杆菌中,ots A基因编码TPS。本试验通过PCR技术克隆ots A基因,构建p2300-ots A-GFP表达载体,用农杆菌介导的方法将ots A基因导入到本生烟草中。对筛选获得的转基因植株进行检测表明,ots A基因已成功整合到本生烟草的基因组中,并能进行有效转录。而且研究发现,转基因幼苗在含有150mmol/L Na Cl的培养基中能够生长,具有一定的抗盐胁迫能力。     

Time course of changes in antioxidant activity of milk from dairy cows fed a trehalose‐supplemented diet

This study was to investigate the time course of changes to the antioxidant activity of milk from cows fed a trehalose‐supplemented diet, and to determine possible underlying mechanisms for observed changes. Six Holstein cows were used, and subjected to two experimental feeding periods consisting of a 1% trehalose‐supplemented diet for 10 days, followed by a basal diet only (no trehalose) for 10 days. 1,1‐Diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activities in milk were gradually increased during the trehalose supplementation period and were highest at the end of the second period. However, trehalose was not detected in the milk and plasma of dairy cows fed a diet supplemented with trehalose for 10 days, indicating that the increased antioxidant activity in the milk of trehalose‐fed cows is not due to the direct transfer of trehalose to the milk. Plasma DPPH activities exhibited a similar time course to that seen for milk. Relative superoxide dismutase (SOD) activities in the rumen were higher 3 days after the end of trehalose supplementation than at any other time during the experimental periods. These results suggested that the improved antioxidant activity in milk and plasma of cows fed a trehalose‐supplemented diet was due to improved ruminal relative SOD activity.     

外源海藻糖对干旱胁迫下烟草幼苗抗旱性的影响

[目的]研究外源海藻糖对烟草（Nicotiana tabacum L.）幼苗生长及抗旱性的影响,从而为其在种子加工及包衣方面的应用提供理论依据。[方法]试验通过PEG6000模拟干旱胁迫环境,比较了不同浓度海藻糖处理后对烟草幼苗生长的影响。[结果]在PEG6000模拟干旱条件下,烟苗明显受到干旱胁迫。外源海藻糖处理后的烟草幼苗在干旱胁迫下可明显提高叶片的相对含水量和叶绿素的含量,降低电导率和MDA的含量,提高POD、CAT和SOD酶活性;统计结果表明,海藻糖处理以浓度为10-15 mmol/L的效果最好。[结论]外源海藻糖可缓解干旱对烟草幼苗生长的胁迫,提高烟苗的抗旱性。     

过表达海藻糖-6-磷酸合成酶拮抗酵母菌工程菌株的构建

本研究构建了带G418抗性的载体pFL61-G418,从酿酒酵母WT303菌株中克隆了真菌抗逆境基因tps1（海藻糖-6-磷酸合成酶基因）,再将tps1基因插入到pFL61-G418载体的NotI位点,构建pFL61-G418-tps1表达载体,并将该表达载体转化进入野生型拮抗酵母膜醭毕赤酵母菌株中。构建过表达海藻糖-6-磷酸合成酶拮抗酵母菌工程菌株,增强拮抗酵母菌的抵抗逆境的生存能力,从而提高其生活力及与病原菌的竞争力。结果表明成功地构建了过表达海藻糖-6-磷酸合成酶拮抗酵母菌工程菌株,说明pFL61穿梭质粒可以用来转化野生型拮抗酵母,G418抗性可以作为转化子筛选的阳性标记。该重组表达载体的成功构建,为野生型拮抗酵母的遗传改良提供了重要的理论依据。     

海藻糖在酿酒酵母抗铜胁迫中的作用

 【目的】研究铜胁迫下,酿酒酵母胞内海藻糖的积累情况及海藻糖对酿酒酵母的保护作用,为探讨铜胁迫下酿酒酵母的防御保护机制提供理论依据。【方法】以改良模拟葡萄汁为发酵培养基,分别对菌株AWRI、BH8和Freddo进行直接铜胁迫处理（Cu2+浓度为1.00 mmol•L-1）、热激预处理（37oC,1 h）、再铜胁迫处理,同时,设定无铜培养为对照。测定各种处理下酿酒酵母的存活率、胞内海藻糖的积累和6-磷酸海藻糖合成酶（TPS1）酶活性的变化。【结果】与对照相比,1.00 mmol•L-1Cu2+胁迫处理使酵母细胞内海藻糖的含量增加,TPS1酶活性提高。热激预处理可诱导海藻糖的积累,且铜胁迫下细胞的存活率也显著高于直接铜胁迫处理。相同处理条件下,菌株Freddo胞内海藻糖的含量最多,细胞存活率也最高。【结论】铜胁迫处理可诱导胞内海藻糖的积累,并且这一积累对铜胁迫下的酿酒酵母起到一定的保护作用。     

蛴螬感染嗜菌异小杆线虫后酶活性和能源物质含量变化

为探究昆虫病原线虫对蛴螬的致病机理,测定了蛴螬感染嗜菌异小杆线虫沧州品系 Heterorhabditis bacteriophora Cangzhou strain后其酚氧化酶（PO）、羧酸酯酶（CarE）活性以及血淋巴蛋白、海藻糖含量的变化。结果表明,线虫侵染后蛴螬 PO 和 CarE 活性大致表现出“升高-峰值-下降”的变化过程,华北大黑鳃金龟 Holotrichia oblita Faldermann、暗黑鳃金龟 H. parallela Motschulsky 和铜绿丽金龟 Anomala corpulenta Motschulsky 3种金龟子2龄幼虫PO活性分别在24、12、36 h达到最大并显著高于对照,CarE活性则分别在48、36、48 h达到最大且显著高于对照。注射线虫悬浮液至铜绿丽金龟3龄幼虫血腔后20 h,血淋巴蛋白含量最高且显著高于对照,28 h含量最低且显著低于对照;海藻糖含量在注射后20 h达到最高但与对照差异不显著,28 h含量最低且显著低于对照。两种酶活性以及能源物质含量的变化,表明嗜菌异小杆线虫入侵对蛴螬免疫系统和代谢过程产生了一定影响,也为揭示昆虫病原线虫对蛴螬的致病机理提供了一定的试验数据。     

取食不同水稻品种对褐飞虱和稻株内海藻糖及海藻糖酶的影响

为明确不同水稻品种与褐飞虱的相互作用关系,以水稻品种TN1(感虫品种)、中浙优1号(生产主栽品种)和IR56(抗虫品种)为研究对象,分别采用蒽酮法和葡萄糖分析试剂测定了褐飞虱取食不同水稻品种后对褐飞虱和稻株体内的海藻糖含量及海藻糖酶活性的影响。结果显示,被褐飞虱取食后,IR56和中浙优1号的海藻糖酶活性分别由无虫状态下的3.56、4.34 nmol·g~(-1)·min~(-1)显著升高至7.53、6.05 nmol·g~(-1)·min~(-1),海藻糖含量分别由12.10、5.14 nmol/μg降至3.14、2.43 nmol/μg,而TN1的海藻糖酶活性由1.46 nmol/μg显著升高至3.05 nmol/μg,海藻糖含量无明显变化。取食TN1、IR56和中浙优1号后,褐飞虱体内的海藻糖含量分别为0.53、0.28和0.20nmol/μg,取食后二者的褐飞虱体内海藻糖含量与TN1组相比较均显著降低;且褐飞虱体内海藻糖酶活性以及3个海藻糖酶基因在mRNA水平均显著低于TN1组。表明海藻糖及海藻糖酶在褐飞虱与抗虫水稻的相互作用中可能发挥着重要的调控作用。