防褐化处理对蒙古栎插穗生根及其生理生化的影响

研究防褐化处理对蒙古栎嫩枝扦插生根的影响。以蒙古栎3年实生苗的嫩枝为材料,分别采用乙醇、硝酸银、抗坏血酸对插穗进行防褐化处理,采用500 mg·L^-1 IBA-K浸蘸处理后扦插,并分别在扦插后0、10、20、30、40、50 d取样测定不同生根时期氧化蛋白酶活性和内源激素含量。结果表明,防褐化处理可有效提高扦插生根率,以1%乙醇1 h+500 mg·L^-1 IBA-K处理2 h最佳,生根率、根系效果指数分别为21.1%和5.713。在生根过程中,外施500 mg·L^-1 IBA-K能够提升插穗内POD、PPO的活性,降低IAAO的活性,且IAA/ABA、IAA/ZR的比值升高,有利于蒙古栎嫩枝扦插生根。由此说明1%乙醇1 h浸泡结合500 mg·L^-1 IBA-K激素处理,通过提高POD与PPO的活性,可降低IAAO的活性,增加IAA/ZR和IAA/ABA的比值,提升蒙古栎嫩枝扦插成活率。     

海洋源芽孢杆菌的分离鉴定及其消化酶代谢产物的测定

【目的】从海洋生物和环境中分离鉴定出产消化酶代谢产物的芽孢杆菌,为微生态制剂的研制提供益生菌种。【方法】从雷州半岛近岸海域采集样品,用高温处理、富集培养和分离培养的方法获得分离菌株;通过菌落形态、细胞结构、染色特征、生化试验和16S rRNA基因测序对分离菌株进行鉴定;采用福林-酚比色法、淀粉-碘比色法和橄榄油乳化法测定分离菌株代谢产物中的蛋白酶、淀粉酶和脂肪酶活性。【结果】从22份样品中初步鉴定出疑似芽孢杆菌43株,筛选3种消化酶综合活性最强的8株,经生化试验和16S rRNA基因测序鉴定,有蜡样芽孢杆菌3株、暹罗芽孢杆菌3株、特基拉芽孢杆菌1株、解木糖赖氨酸芽孢杆菌1株。其中,解木糖赖氨酸芽孢杆菌BC1产脂肪酶活力最高,为52.13 U/mL;蜡样芽孢杆菌BC3产蛋白酶活力最高,为4.78U/mL;暹罗芽孢杆菌BC6产淀粉酶活力最高,为2.35 U/mL。【结论】成功筛选出产消化酶代谢产物的海洋源芽孢杆菌。     

红曲菌固态发酵产消化酶生产工艺优化

【目的】红曲菌在生长代谢过程中会产生多种酶类物质,为优化红曲菌发酵产消化酶的生产工艺。【方法】研究7株红曲菌固态发酵产物中的液化酶、糖化酶及蛋白酶活性,筛选出酶活相对较高的菌株ZH6。分别研究发酵时间、基质加水量、接种量及培养温度对红曲菌ZH6固态发酵所产糖化酶、液化酶及蛋白酶活性的影响。在单因素试验基础上分别以加水量、接种量及培养温度作为自变量,以红曲菌ZH6固态发酵产物中糖化酶、液化酶及蛋白酶的活性为因变量进行响应面优化。【结果】经响应面优化生产工艺,当紫色红曲菌ZH6固态发酵的加水量为42 mL、接种量为20%、培养温度为33 ℃、发酵培养6 d时,所生产的液化酶活性达到119.27 U/g;当加水量为38 mL、接种量为20%、培养温度为30 ℃、发酵培养10 d时,所生产的糖化酶活性为614.32 U/g;当加水量为35 mL、接种量为20%、培养温度为31 ℃、发酵培养7 d时,所生产的酸性蛋白酶活性为1 194.21 U/g。【结论】响应面法优化生产工艺,能有效提高红曲菌ZH6产消化酶的能力。     

1种可用于检测WSSV蛋白酶的微量酶活测定技术

以酪蛋白为底物 ,对常规蛋白酶检测方法进行改进并与偶氮酪蛋白法进行比较 ,建立适应病毒微量蛋白酶的快速检测方法。结果表明 ,改进的微量蛋白酶检测方法具有微量、快速、灵敏度高的特点 ,适于病毒微量蛋白酶的检测。蛋白酶的最低检出量可达ng级。     

高植物蛋白饲料中添加蛋白酶对克氏原螯虾生长、免疫力及消化力的影响

为探讨低鱼粉高植物蛋白饲料中蛋白酶的适宜添加范围,在克氏原螯虾基础饲料中分别添加0、0.1、0.2、0.4、0.8、1.6 g/kg蛋白酶,制作成6组饲料。选择初始体质量为(8.18±0.11) g的克氏原螯虾,随机分为6组,每组3个重复,每个重复15尾虾,在室内养殖桶中饲养8周。结果显示,随饲料蛋白酶添加量的增加：(1)各组间存活率、肝体比、腹部含肉率均无显著差异;增重率和特定生长率均先升高后降低,且在蛋白酶添加量为0.2 g/kg时达到最大值。当蛋白酶添加量为0.4 g/kg时饲料系数最低;蛋白质效率和蛋白质沉积率分别在添加量为0.4和0.2 g/kg时达到最高值。经折线回归分析,增重率、饲料系数、蛋白质效率分别在蛋白酶添加量为0.16、0.24、0.23 g/kg时有最佳值。(2)腹部肌肉和全虾粗蛋白质含量先升高后降低最终趋于平稳,均在0.2 g/kg组有最大值。(3)肠道及肝胰腺蛋白酶、脂肪酶、淀粉酶活性均先增加后缓慢降低,均在0.2 g/kg组出现最大值,且显著高于对照组。(4)血清总蛋白含量在0.4 g/kg组出现最大值;谷草转氨酶及谷丙转氨酶活性先降低后增加,均在0.4 ...     

中华鲟半胱氨酸蛋白酶抑制剂C基因的原核表达

为了研究鱼类半胱氨酸蛋白酶抑制剂(cystatin)的功能并探索其在水产品加工和病害防治中的应用潜力，将改造后的中华鲟(Acipenser sinensis)cystatin C cDNA亚克隆到原核表达载体pBV220，构建表达cystatinc的大肠杆菌基因工程菌。该工程菌经温度诱导、SDS—PAGE检测，在约12．4kD处有一特异蛋白带，该特异蛋白的含量约为菌体总蛋白的25％。重组半胱氨酸蛋白酶抑制剂经洗涤、溶解、透析、复性后纯度为85％，实现了中华鲟cystatinC在大肠杆菌中的高效表达。木瓜蛋白酶活性抑制实验结果表明该重组cystatinc具有明显的酶活抑制作用。     

欧鳗黑仔苗在不同盐度条件下生长效果的比较

本实验主要研究欧鳗黑仔苗在盐度分别为0、5、10和15的水体中的生长差异.实验结果表明,盐度对欧鳗黑仔苗的生长和体内蛋白酶活性具有显著的影响(P＜0.05);对欧鳗黑仔苗的成活率没有影响(P＞0.05);对欧鳗黑仔苗的总摄食量、饵料系数有显著的影响(P＜0.05).盐度为10时生长速度最快,饵料系数最低.     

Purification and characterization of stomach protease from the turbot (Scophthalmus maximus L.)

Proteolytic activity in the different parts of the digestive tract of the turbot (Scophthalmus maximus L.) were studied in this work. One pure protease was isolated from turbot stomach and its behavior was studied. Results showed the optimum pH for proteases in the different parts of the digestive tract of the turbot were pH 2.0 for the stomach, pH 8.0 for the pylorus cecum, pH 8.0 for the foregut, pH 8.5 for the midgut, and pH 8.0 for the hindgut. The activity of proteases in the different parts of the digestive tract were in the sequence pylorus cecum protease > stomach protease > foregut protease > midgut protease > hindgut protease. The stomach protease was purified by ammonium sulfate precipitation and column chromatography on DEAE-Sepharose F.F. and Sephadex G-100. The purified enzyme gave a single band in SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Its molecular weight was found to be approximately 42,000 Da. The enzyme is stable at pH 1.0–9.0 and at temperatures below 40°C. Its activity was maximum at pH 2.0 and 40°C. When reaction time was prolonged the optimum temperature of the enzyme tended to decline. The enzyme was activated by Mn²⁺ and Cu²⁺ and inactivated by Fe³⁺. It was fully inhibited by pepstatin and partially inhibited by PMSF, TPCK, PCMB, and NBS. These results imply the enzyme is a pepsin.     

Characterization of chymotrypsin activity during early ontogeny of larval red drum (Sciaenops ocellatus)

The temporal evolution of chymotrypsin activity during early ontogeny of laboratory reared red drum larvae was accomplished using a combination of biochemical assays and electrophoretic methods (substrate SDS-PAGE). Optimal functional conditions for chymotrypsin were also determined. Chymotrypsin activity was first detected prior to the onset of exogenous feeding. Total chymotrypsin activity increased with age and standard length. Specific activity was greatest on day 10 post-hatch. Maximal chymotrypsin activity was observed at 50 °C, pH 7.8, and Ca²⁺ concentration of 25 mM. Using substrate gel electrophoresis and specific inhibitors the molecular weight of red drum chymotrypsin was estimated to be 26–27 kD. Our results indicate that the digestive system of red drum larvae is capable of alkaline proteolysis before first feeding and suggest that chymotrypsin may have potential as an indicator of nutritional condition.