稻瘟菌的胞外纤维素酶和果胶酶活性的研究

液体培养5种稻瘟菌生理小种.随着培养天数增加,ZC_3、ZD_1和ZG_1培养液中纤维素酶活性增高较快,而ZE_1和ZF_1增高较慢.培养液中纤维素酶活性增高快的,葡萄糖含量增加也快.培养8天的稻瘟菌培养液中各生理小种果胶酶活性高低顺序,果胶甲酯酶为:ZD_1>ZC_3>ZG_1>ZE_1>ZF_1;多聚半乳糖醛酸酶活性为:ZD_1>ZC_3>ZE_1>ZF_1>ZG_1.研究表明,胞外纤维素酶和果胶酶活性高的稻瘟菌生理小种,其致病性也强.     

中药复方体内抗内毒素实验研究

目的：对91味中药及复方进行体内抗内毒素试验研究。方法：将筛选到的以牡丹皮、贯众等为主的3个中药复方分别对小白鼠灌胃给药,后进行内毒素攻毒试验,研究不同组方对内毒素攻毒后小白鼠的保护作用。结果：方2、方5、方6对内毒素攻击所致小鼠死亡有非常显著的保护作用,尤其是方2。结论：以牡丹皮、贯众等为主,具清热解毒、活血散瘀、凉血止血功能的复方中药具有极显著的体内抗内毒素作用,可望为猪高热综合征的预防和治疗提供新的途经。     

柑橘类植物精油的抗菌活性及其作用机制

柑橘类植物精油(CEOs)是从柑橘类植物中提取的芳香类混合物,其主要活性成分为D-柠檬烯(D?limonene),具有广泛的生物活性,包括抗菌、抗氧化和抗炎等.CEOs具有选择性抗菌活性,在动物生产中具有非常重要的应用价值.不同的CEOs具有不同的抗菌活性,研究其抗菌机制也具有非常重要的意义.本文着重介绍了CEOs的化...     

番荔枝主要虫害防治及其杀虫活性研究概述

就当前番荔枝(Annona squamosa L.)生产中主要的虫害及其杀虫活性的研究进展进行了阐述,对番荔枝生产过程中存在的主要虫害的症状、发生规律及防治方法进行了总结,并对我国未来番荔枝虫害的综合防治技术进行了初步探讨。     

Distribution of phosphatase activity and various bacterial phyla in the rhizosphere of Hordeum vulgare L. depending on P availability

Despite the importance of the rhizosphere for nutrient turnover, little is known about the spatial patterns of organic phosphorus mineralization by plants and by microorganisms in the rhizosphere. Therefore, the distribution of acid and alkaline phosphatase activity and the abundance of bacteria belonging to various bacterial phyla were investigated in the rhizosphere of barley (Hordeum vulgare L.) as dependent on the availability of inorganic P. For this purpose, we conducted a greenhouse experiment with barley growing in inclined boxes that can be opened to the bottom side (rhizoboxes), and applied soil zymography and fluorescence-in situ-hybridization (FISH). Acid phosphatase activity was strongly associated with the root and was highest at the root tips. Due to P fertilization, acid phosphatase activity decreased in the bulk soil, and less strongly in the rhizosphere. Alkaline phosphatase activity, i.e., microbial phosphatase activity was high throughout the soil in the control treatment and was reduced due to inorganic P fertilization especially in the rhizosphere and less strongly in the bulk soil. P-fertilization slightly increased the total number of bacteria in the rhizosphere. Moreover, P-fertilization decreased the abundance of Firmicutes and increased the abundances of Beta- and Gamma-Proteobacteria. The total number of bacterial cells was significantly higher at the root surface than at the root tip and at a distance of 30 μm from the root surface. Our results show that alkaline phosphatase activity decreased more strongly in the rhizosphere than in the bulk soil due to P fertilization, which might be because of greater C deficiency in the bulk soil compared to the rhizosphere. Furthermore, the results indicate a spatial separation between hotspots of acid phosphatase activity and hotspots of bacteria in the rhizosphere of H. vulgare. Taken together, our study shows that bacteria and phosphatase activity were very heterogeneously distributed in soil, and that the effects of P fertilization on phosphatase activity differed strongly between bulk soil and rhizosphere as well as between various zones of the rhizosphere.     

高效溶栓菌株的筛选鉴定及活性测定

以日本纳豆、重庆江津豆豉、忠县豆腐乳为原料,采用酪蛋白平板初筛、摇瓶复筛,得到18株产溶栓酶的菌株.通过纤维蛋白平板实验,从忠县豆腐乳中筛选出1株具有较高溶栓活性的菌株FR-033(登录号:HQ009804),菌株经液体发酵后获得含酶发酵液,采用硫酸铵分段盐析及sephadexG-50凝胶层析进行纯化,获得较高纯度的溶栓酶,酶活力为2 163 IU/mL.进一步对FR-033菌株的形态和生理生化特征进行研究.利用细菌16S rDNA通用引物对16S rRNA进行PCR扩增并测序,得到1444 bp长度的DNA序列,通过BLAST软件在NCBI网站收索其同源性性序列,利用PAUP4.0和MAGE4软件绘制系统发育树,结果表明:菌株FR-033与枯草芽孢杆菌(Bacil-lus subtilis)的16S rRNA序列同源性达99%以上,在系统发育树中,菌株FR-033与枯草芽孢杆菌在同一支上,且遗传距离最短;FR-033的形态及大部分生理生化特征与枯草芽孢杆菌极为相似,表明该菌株是枯草芽孢杆菌(Ba-cillus subtilis)的一个高效的产溶栓酶菌株.     

硫素对冬小麦籽粒蛋白质积累的影响

在0～20 cm土层有效硫含量为5.84 mg/kg地块上施硫,显著提高冬小麦根系和旗叶硝酸还原酶活性,增加旗叶总游离氨基酸和可溶性蛋白质含量,利于旗叶蛋白质的合成;施硫亦提高旗叶内肽酶和羧肽酶活性,加速旗叶蛋白质的降解.施硫67.5 kg/hm2促进籽粒谷蛋白积累,显著提高籽粒蛋白质含量,改善加工品质,增加籽粒和蛋白质产量,但对醇溶     

黑松松针多糖的复合酶法提取及其抑菌性研究

为了优化复合酶提取黑松松针多糖的工艺,并考察其抑菌性,根据松针粉的结构特点选取纤维素酶、果胶酶高效提取黑松松针多糖,在单因素试验的基础上,采用正交试验对这两种酶提取松针多糖的条件(液料比、酶添加量、酶解温度、酶解时间、pH)进行优化。根据优化后的工艺条件,建立了双酶复合提取黑松松针多糖的工艺,且证实分步加酶法提取的多糖得率较高,即:液料比20∶1(mL/g),酶解温度50℃,pH 6.5,先添加2.5%纤维素酶,酶解时间2 h,后添加1.5%果胶酶,酶解时间1.5 h。此条件下得到的黑松松针多糖得率达6.17%,远高于单酶提取效果。松针多糖对大肠杆菌和枯草芽孢杆菌有较好的抑菌效果。该方法简便,可用于提取黑松松针多糖,为松针的开发利用提供技术基础和方法。     

水势与土壤-植物-大气连续体系中的水分运动

本文从自由焓(吉氏自由能)和化学势分别推出溶液和空气的水势公式ψ=P-∏+ρ_wgh,ψ=RT/(?)_wInH+ρ_wgh。并由此讨论土壤学和植物生理学普遍直接引用的水势分量方程ψ=ψ_p+ψ_s+ψ_m+ψ_g,说明细胞、土壤和大气的水势。然后应用水势概念处理土壤-植物-大气连续体系中的水分运动,阐明传统术语“蒸腾拉力”和“根压”作用及水势在连续体系的分布和日变化等问题。     

长白山蜂胶的生物活性分析

对长白山蜂胶的抗氧化、抗疲劳和抑菌能力进行了分析.结果表明,该蜂胶清除羟基、DPPH和超氧阴离子3种自由基的能力随其浓度的增大而增强;蜂胶可显著延长小鼠游泳、爬杆力竭时间,小鼠的肝糖原和肌糖原储备显著增加,血乳酸变化幅度很小;蜂胶对细菌的抑制作用明显强于真菌,对9种细菌的最小抑制浓度MIC为25～1 600 μg/mL.长白山蜂胶具有较强的生物活性.