嗜热芽孢杆菌高温蛋白酶HS08的化学修饰研究

分离纯化了嗜热芽孢杆菌产生的耐高温蛋白酶HS08,以SDS-PAGE凝胶电泳和Superdax75预装柱凝胶过滤,测定蛋白酶HS08的分子质量为30.6ku,同时研究了酶专一性抑制剂对酶活性的影响。结果表明,蛋白酶HS08的活性被酶活性中心丝氨酸残基专一性抑制剂PMSF以及金属离子螯合剂EDTA强烈抑制,而NBS、WRK、TNBS、Phenylgloxalhydrate等修饰剂对酶活性无明显抑制作用。K+、Na+、Ca2+、Mg2+、Zn2+等金属离子对酶活性影响实验结果表明,Zn2+可使该酶活性明显提高,Cu2+对该酶活性有抑制作用。因此,该酶属于金属离子激活的丝氨酸族蛋白酶。蛋白酶HS08的酶动力学实验表明,以BSA为底物,PMSF可使蛋白酶HS08最大反应速率Vmax下降50%,而对其米氏常数Km影响不大。     

响应面法优化螺旋藻自溶条件的研究

以新鲜螺旋藻藻泥为原料,通过响应面实验设计方法对螺旋藻自溶条件进行优化。以可溶性肽含量为响应变量,温度、pH以及Na+浓度为自变量,应用中心复合设计-一致精度(CCD Uniform precision)法设计实验,轴值取1.43,6个中心点,共20组实验。实验结果表明,螺旋藻自溶最适温度为48.6℃、pH为9.6以及Na+浓度为1.00mol/L,最适条件下螺旋藻自溶1hTCA-可溶性肽含量比未优化(室温25℃,加蒸馏水)下高6.35倍。     

响应面优化酸和热处理对玉米醇溶蛋白的改性

以玉米醇溶蛋白为原料,经超声波预处理后,再利用酸和热的复合处理对玉米醇溶蛋白进行改性,并用响应面法对改性条件进行优化,最后比较改性前后蛋白质的性质.结果表明,玉米醇溶蛋白的最佳改性条件为:HCl的浓度为0.4 mol/L,温度为92℃,时间为2.5h.玉米醇溶蛋白的溶解度显著增加;乳化性有所增加,但是不显著;起泡性则显著增加;而表面疏水性显著降低.     

Optimization of succinic acid production from cane molasses by Actinobacillus succinogenes GXAS137 using response surface methodology (RSM)

A method combining a Plackett-Burman design (PBD), the steepest ascent method (SA), and a Box-Behnken design (BBD) was developed to optimize succinic acid production from cane molasses by Actinobacillus succinogenes GXAS137. The important parameters were (g/L): total sugars of cane molasses (85 g/L), yeast extract (8.84 g/L), and MgCO₃ (63.1 g/L). Verification experiments indicated that the maximal succinic acid production reached 57.43±0.86 g/L, which agreed with the predicted value (57.12 g/L). In addition, batch and fed-batch fermentations were carried out in a 1.3 L stirred bioreactor. Compared with a batch fermentation that produced 57.96 g/L of succinic acid at 60 h, a fed-batch fermentation, performed to minimize the inhibition effect of the substrate, produced 64.34 g/L of succinic acid at 60 h. The combined method is powerful for selection of optimized conditions for succinic acid production from cane molasses.     

Development of shelf stable pepper based appetizers by response surface methodology (RSM)

The paper deals with three pepper-based appetizers developed in the form of convenient beverage mixes. The optimization of ingredients in the formulations of spiced drink mix, spiced tomato mix and chakota soup mix was achieved using response surface methodology with statistical design software. The active ingredient pepper was 1.5 and 2.8/100 g as black pepper and 9/100 g as white pepper with total pungency (expressed as piperine, g/100 g) of 0.08, 0.155, 0.155 in spiced drink mix, chakota soup mix and spiced tomato mix, respectively. The appetizer mixes packed in paper/Al foil/ polythene (PFP) and polypropylene (PP) pouches were stored at ambient temperature as well as 37 °C. Periodic evaluation (2-months interval) revealed that spice drink mix and spiced tomato mix had a shelf life of 6 months, while it was 8 months for chakota soup mix packed in PFP pouches under ambient conditions (18-33 °C).     

响应面法优化嗜麦芽窄食单胞菌产蛋白酶发酵培养基

目的:通过对嗜麦芽窄食单胞菌（Kx-7）的发酵培养基进行优化来提高蛋白酶活力。方法:首先利用单因素实验确定影响Kx-7产蛋白酶的碳源、氮源及表面活性剂的种类和浓度范围;在此基础上,应用Box-Behnken实验设计对影响蛋白酶活力的显著因素进行优化,最终建立了以蛋白酶活力为响应值的二次回归方程模型,获得了最适的Kx-7产蛋白酶发酵培养基。结果:具有显著效应的三个因素分别为D-果糖,酪蛋白和Triton X-100,三者最佳浓度分别19.15g/L、4.05g/L和5.1mL/L。优化后嗜麦芽窄食单胞菌Kx-7产酶酶活提高到324.56U/mL,比初始酶活146.43U/mL提高了1.2倍。结论:响应面实验优化了Kx-7发酵培养基,大大提高蛋白酶的产量,有望用于大规模生产。      

Optimizing conditions for anthocyanins extraction from purple sweet potato using response surface methodology (RSM)

Optimization for purple sweet potato (Ipomoea batatas (L.) Lam) anthocyanins (PSPAs) extraction was investigated using response surface methodology in this paper. PSPAs were extracted using acid-ethanol at different extraction temperature (40-80 °C), time (60-120 min) and solid-liquid ratio (1:15-1:30). The combined effects of extraction conditions on PSPAs yield and color attributes (expressed as L*, C* and H) were studied using a three-level three-factor Box-Behnken design. The results showed that The highest yield (158 mg/100 g dw) of PSPAs were reached at the temperature 80 °C, extraction time 60 min, and solid-liquid ratio 1:32. PSPAs yield indicated a high and significant correlation with L^* (P<0.05; r=−0.961) and it was significantly affected by extraction temperature (P<0.01) and solid-liquid ratio (P<0.05).     

响应面分析法优化猪骨素提取工艺条件的研究

利用响应面法对猪骨素的提取工艺进行优化。在单因素实验基础上选取主要的实验因素与水平,根据中心组合(Box-Benhnken)实验设计原理,采用三因素三水平的响应面分析法,依据回归分析确定各工艺条件的影响因素,以提取液中的胶原蛋白含量和游离氨基酸含量的综合指标为响应值作响应面回归。在分析各个因素的显著性和交互作用后,得出猪骨素提取的最佳工艺条件:提取压力为0.11MPa,时间为226min,液料比为3:1。在此条件下,实际测得综合指标含量为0.5339%。     

响应面法优化丙酮酸发酵培养基

采用响应面法(RSM)对丙酮酸发酵培养基成分葡萄糖、硫酸铵、蛋白胨进行优化,采用多元二次回归方程拟合3种因素与丙酮酸含量间的函数关系,并得到了最佳条件。在优化培养条件下,发酵液中丙酮酸的浓度由35.4g/L提高到41.57g/L,在5L罐的最佳浓度下丙酮酸产量71.23g/L比原产量65.76g/L提高8.3%。     

响应面优化化橘红柚皮苷超声辅助提取工艺

为了研究化橘红药用价值、开发柚皮苷产品,本文通过单因素实验以及响应面优化对化橘红中柚皮苷的超声波辅助乙醇浸提工艺进行了研究,结果表明,化橘红中柚皮苷最佳的提取工艺参数为提取温度57.5℃,液料比60.9(mL·g^-1),乙醇体积分数为50.8%;化橘红柚皮苷的实际得率为7.87%,接近于响应面预测值7.95%,因此响应面优化柚皮苷的超声波辅助提取工艺真实可信,超声波辅助提取效率高。