绵羊瘤胃微生物胞外蛋白酶性质的研究     

杨开伦  许键  余雄  梁其英 《动物营养学报》1994,(1)

本试验测定了pH、温度和EDTA对纯化的绵羊的瘤胃微生物胞外蛋白酶活性的影响,并用一已知氨基酸排列顺序的肽段(由15个氨基酸组成)作为底物,进一步测定了蛋白酶的酶切位点。结果表明,(1)纯化蛋白酶的最适pH在6.0～6.5之间,最适温度为40℃左右。(2)不同浓度的EDTA(浓度分别为1,10,25,50,75和100mM)对蛋白酶活性没有影响,因而该酶属于丝氨酸蛋白酶类。(3)纯化蛋白酶是一种内肽酶,其酶切位点在组氨酸—酪氨酸(?)、天冬氨酸—丙氨酸(?)、亮氨酸—赖氨酸(?)和(或)缬氨酸—赖氨酸(?)相连的肽键。(4)胰蛋白酶和纯化的蛋白酶虽同属丝氨酸蛋白酶类,但前者对底物具有高度的专一性,后者对底物的专一性不强,这是瘤胃内饲料蛋白质强烈降解的主要原因之  相似文献   

灵芝胞外多糖高产菌株筛选及其深层发酵培养基的优化   总被引：12，自引：2，他引：12  

宋频然  常继东 《食用菌学报》2003,10(2):9-16

运用反馈抑制理论构建了耐灵芝胞外多糖 (EPS)反馈抑制的筛选模型。添加在筛选培养基中的其指示因子同源胞外多糖浓度为 2 .34g/L。将实验室保藏的 37株灵芝菌株输入该模型 ,即可检出耐灵芝胞外多糖反馈抑制作用最强、产胞外多糖能力最强的菌株GL0 2 9。然后在基础培养基的基础上用正交试验方法优化GL0 2 9深层发酵培养基。结果表明 ,组合碳源和组合氮源培养基最适合该菌株深层发酵生产灵芝胞外多糖。深层发酵培养基配方为 :蔗糖 10 g/L ,玉米粉15 g/L ,蛋白胨 2 g/L ,酵母膏 1g/L ,KCl 0 .5g/L ,KH2 PO4 ·7H2 O 0 .5 g/L ,pH自然。于 30℃、12 0r/min摇瓶培养 9d ,该菌株的胞外多糖产量高达 3.0 7g/L。  相似文献   

The role of adrenomedullin in diabetic nephropathy     

LI Hui-min  MIAO Heng  JIANG Xiu-qin 《园艺学报》2004,20(4):643-646

AIM: To investigate the role of adrenomedullin (AM) in diabetic nephropathy. METHODS: We observed the changes in the expression and secretion of AM, TGF-β₁ in the cultured human mesangial cells under high glucose condition and the contents of the laminin and type IV collagen in the supernatants. The effect of intervention with AM was also observed. RESULTS: High glucose condition resulted in increase in the expression and secretion of AM、 TGF-β₁、 laminin and type IV collagen. AM reversed the influence of high glucose on the cultured human mesangial cells. CONCLUSION: These results showed that high glucose condition is one of stimulating factors of AM and the renal protective action of AM may be associated with suppression of TGF-β₁ and reducing excessive accumulat ion of laminin and type IV collagen.  相似文献   

Synergistic effects of soil microstructure and bacterial EPS on drying rate in emulated soil micromodels     

《Soil biology & biochemistry》2015

Microbial extracellular polymeric substances (EPS) have been shown to alter soil moisture retention and to improve seedling survival and plant growth at the bulk scale. The mechanisms of EPS-mediated water retention include reversible swelling of the cross-linked polymer matrix and the promotion of an aggregated soil structure. However, the effects of EPS on water retention have never been directly observed at the pore scale. Here, emulated soil micromodels were developed to directly observe the effects of physical, chemical, and biological factors on pore-scale water retention. In this demonstration, a pseudo-2D pore structure was created to represent physical features of a fine sandy loam. Replicate micromodels were initially saturated with suspensions of different soil bacteria, and pore-scale air infiltration was directly imaged over time. External evaporativity was held constant through the use of a custom constant-humidity environmental chamber. Micromodels filled with suspensions of highly mucoid Sinorhizobium meliloti retained moisture about twice as long as physically identical micromodels filled with suspensions of non-mucoid S. meliloti. Relative drying rates in six replicate experiments ranged from 1.1 to 2.5 times slower for mucoid suspensions. Patterns of air infiltration were similar but not identical across replicates. The results suggest that pore fluid EPS and micromodel geometry act together to limit evaporation at pore throats. Advantages of the micromodel approach include direct observation of pore-scale dynamic process, and the ability to systematically replicate complex physical structures. These abilities will enable users to screen benefits from different structures and from microbial compositions, and build predictive understanding of the overall function of microbe-habitat systems.  相似文献   

木霉菌胞外酶及对番茄灰霉病菌作用的研究   总被引：1，自引：0，他引：1  

郭培磊  刘限  高增贵  庄敬华  赵岩 《北方园艺》2009,(8)

研究了木霉菌T21及其4种长势好抗逆性较强的REMI转化体对番茄灰霉病菌抑菌能力,温室防效以及其发酵液中几丁质酶、-β1,3-葡聚糖酶和纤维素酶的活性。结果表明:5株木霉菌株对番茄灰霉病病菌都有不同程度抑制作用,其中Ttrm68抑制效果最好,培养一定时间后,木霉可以把番茄灰霉病菌完全覆盖;温室防效也是Ttrm68的效果最好。胞外酶活性的测定结果表明:对番茄灰霉菌抑制效果好的木霉菌几丁质酶和-β1,3-葡聚糖酶的活性高,而纤维素酶活性则没有明显的规律。  相似文献   

克雷伯氏菌胞外多糖的制备与组成分析   总被引：1，自引：0，他引：1  

刘志鸿  牟海津 《海洋水产研究》2008,29(1):7-11

利用不同血清型的克雷伯氏菌Klebsiella菌株液体发酵,制备胞外多糖,并采用气相色谱和化学分析方法分析胞外多糖的化学组成。结果表明,菌株K26产胞外多糖的能力最高,培养48h和72h的产量分别为3.11mg/ml和3.89mg/ml;各实验菌株的胞外多糖的单糖组成包括甘露糖、葡萄糖和半乳糖。  相似文献   

Transcriptome analysis reveals transforming growth factor-β1 prevents extracellular matrix degradation and cell adhesion during the follicular-luteal transition in cows     

Binbin GUO  Xiaolu QU  Zhe CHEN  Jianning YU  Leyan YAN  Huanxi ZHU 《The Journal of reproduction and development》2022,68(1):12

  相似文献   

十字花科黑腐病菌中转录调控因子HpaR1调控一个纤维素酶基因的表达     

薛番艳  苏辉昭  刘兴艳  梁伟  李磊  李瑞芳  陆光涛 《广西农业生物科学》2012,(4):333-340

十字花科黑腐病菌（Xcc8004）中的一个转录调控因子XC2736（npaRI）在致病过程中具有重要的作用。前期研究发现该转录调控因子可能调控胞外纤维素酶的合成。为了解HpaRI对纤维素酶的转录调控机理,本研究对HpaR1进行原核表达纯化,并与488bp的包含XC0639的启动子区DNA片段进行凝胶电泳迁移率试验,发现HpaR1与XC0639启动子可以发生结合。将488bp的XC0639的启动子DNA片段与报告基因gus融合,构建XC0639的报告质粒pGUS0639r,分别导入野生型8004菌株和缺失突变体DM2736中,分析发现在突变体背景下GUS的表达水平比野生型背景明显降低。表明HpaRl正调控XC0639的表达。构建XC0639的极性整合突变体PK0639,检测发现PK0639几乎丧失胞外纤维素酶的活力;通过功能反式互补构建的互补菌株CPK0639可以恢复纤维素酶活性。研究结果表明HpaRl通过调控纤维素酶基因XC-0639的表达来调控细胞的纤维素酶活性。本研究为更深入地了解HpaR1如何调控细菌生理生化功能奠定了基础。  相似文献   

猪链球菌2型epf基因的原核表达及其蛋白纯化     

葛长城  王海丽  徐公义 《安徽农业科学》2009,37(15):6916-6917

为了克隆、表达SS2菌株轲基因片段,分析蛋白活性,根据GenBank SS2 epf基因序列设计引物,克隆epf基因片段并进行序列分析,构建原核表达质粒pGEX4T-2-epf,在大肠杆菌中诱导带有GST标签的融合蛋白rEF-GST的表达;亲和层析法纯化融合蛋白rEF-GST,用凝血酶切除重组蛋白中的GST,获得纯化的EF抗原。经Westernblot鉴定,EF可与SS2多克隆抗血清发生特异性反应。  相似文献   

水稻纹枯病菌胞外蛋白酶分离纯化及部分特性分析     

范文艳  陈瑾  文景芝  马建  石园园 《安徽农业科学》2010,38(15):7921-7923

[目的]为深入研究水稻纹枯病菌的致病机理奠定基础。[方法]水稻纹枯病菌（Rhizoctonia solaniKhn）发酵液经硫酸铵沉淀,用离子交换柱层析、疏水层析和分子筛层析方法分离纯化胞外蛋白酶。[结果]从水稻纹枯病菌发酵液中分离纯化到一个分子量约为49.5ku的胞外蛋白酶。其活性最适温度为30℃,最适pH为6.4。Zn^2＋、Fe^3＋、Cu^2＋对酶活性有抑制作用,Mg^2＋、Mn^2＋对酶活性无影响,Ca^2＋在低浓度下对酶活性有激活作用。[结论]水稻纹枯病菌可产生胞外蛋白酶,该胞外蛋白酶与水稻纹枯病菌致病性的关系还有待深入研究。  相似文献