在糖化酶发酵生产中低温保存黑曲霉菌

在糖化酶生产过程中,为了防止正常生产中黑曲霉菌种性能的变化,对菌种的一级种母进行甘油冷冻保存,在-120℃的条件下分别保存30、60、90d,然后直接接入种母培养基,待成熟后接入种子罐,投入50t发酵罐工业生产,150h左右发酵结束。产酶单位与原工艺条件相一致。     

泸型大曲中根霉固态发酵产糖化酶条件研究

对泸型大曲中根霉菌株固态发酵产糖化酶的条件进行了研究。以糖化酶活力为评价指标,设计单因素实验,研究培养基水分含量、培养时间、培养温度对根霉产糖化酶的影响,在此基础上,利用Box—BenhnkenDesign的方法,对根霉菌株固态发酵产糖化酶的条件进行优化,结果显示泸型大曲中根霉菌株固态发酵产糖化酶的优化条件为培养温度29℃,培养基水分含量53％,培养时间164h,糖化酶的酶活力为2194．44U／g。     

PVP/(NH4)2SO4液-固萃取法提取糖化酶的研究

以聚乙烯吡咯啉酮（PVP）／（NH4）2SO4液-固萃取体系研究了工业糖化酶的萃取分配行为。萃取的适宜条件为10％PVP（K30），1．36mol．L^-1（NH4）2SO4，pH4．6。糖化酶浓度直接影响固-液两相的分配行为。在此条件下，该体系可成功实现对糖化酶的提取。     

新型糖化酶在淀粉制葡萄糖中的应用

在玉米淀粉双酶法制糖工艺中使用OPTIMAX4060VHP强效液体糖化酶,使工艺操作简单方便,生产更加稳定;降低可逆反应,提高糖液的葡萄糖含量;节约蒸汽;提高糖液透光率和糖液质量,具有良好的经济效益。     

Cultivable bacterial diversity and amylase production in three typical Daqus of Chinese spirits

Both culture‐dependent method and molecular technique were firstly used to simultaneously investigate the cultivable bacterial diversity and amylase production in three typical Daqus of Chinese spirits. The results showed that both cultivable bacterial diversity and amylase production were obviously different. The species of nine bacteria from Deshan, nine from Baisha and six from Wuling Daqus were identified. The total bacterial strains of 17, 15 and 14, and 9, 16 and 10 could produce α‐amylase and glucoamylase, respectively, from the Daqus, and the enzyme yields were different. Bacillus licheniformis, Bacillus subtilis and Bacillus amyloliquefaciens not only were dominant bacteria in the Daqus, but also possessed high activities of α‐amylase and glucoamylase. By comparison, Bacillus cereus and Bacillus oleronius were found to be another predominant bacterial species and good producers of α‐amylase and glucoamylase in Deshan and Wuling Daqus, respectively.     

Kinetics and thermodynamics of glucoamylase inhibition by lactate during fermentable sugar production from food waste

BACKGROUND: Glucoamylase hydrolysis is a key step in the bioconversion of food waste with complicated composition. This work investigated the effect of lactate on glucoamylase from Aspergillus niger UV‐60, and inhibition mechanisms of glucoamylase by lactate during food waste hydrolysis. RESULTS: For 125 min hydrolysis of food waste (10%, dry basis), reducing sugars produced in the absence of lactate were 15%, 26% and 56% more than those produced in the presence of 24 g L^?1 lactate at 60, 50 and 40 °C, respectively. Kinetic study showed that the type of glucoamylase inhibition by lactate was competitive, and K_m (Michaelis‐Menten constent), V_max (maximum initial velocity), K_I (inhibition constant) were 103.2 g L^?1, 5.0 g L^?1 min^?1, 100.6 g L^?1, respectively, for food waste hydrolysis at 60 °C and pH 4.6. Lactate also accelerated glucoamylase denaturation significantly. Activation energy of denaturation without inhibitor was 61% greater than that of denaturation with inhibitor (24 g L^?1 lactate). Half‐lives (t_1/2) without inhibitor were 7.6, 2.7, 2.6, 1.7 and 1.2 times longer than those with inhibitor at temperature 40, 45, 50, 55 and 60 °C, respectively. CONCLUSION: These results are helpful to process optimization of saccharification and bioconversion of food waste. Copyright © 2010 Society of Chemical Industry     

沉淀法去除糖化酶中转苷酶的研究

研究了磷钨酸，十二烷磺酸钠，单宁酸三种试剂去除液体曲糖化酶中转苷酶的方法，利用正交试验了每种方法的最优工艺条件，在最优工艺条件下，磷钨酸法转苷去除率为７５．９％，糖化酶活力损失９．６％，十二烷基磺酸钠法转苷酶去除率为６９．１％，糖化酶活力基本不变；单宁酸法转苷酶去除率为７０．３％，糖化酶活力提高９．８％。     

球形壳聚糖固定化糖化酶的研究

研究了以球形壳聚糖作载体固定化糖化酶的方法，探讨了戊二醛用量，酶量，温度，pH值对固定化效果的影响。     

戊二醛交联糖化酶的条件探索及协同实验教学分析

介绍了在生物工程实验中探索利用分组协同创新模式进行实验教学的成果。将一个教学自然班分成12个实验小组,每组同学3人。以可能影响实验结果的四个变量分解成四个独立又互相联系的实验,每个变量分别由三组学生负责研究,研究过程通过定期协调沟通对实验结果进行分析总结并不断优化实验设计,得出了优化实验工艺,同时也培养了学生独立思考和协作配合的精神。实验研究了戊二醛交联糖化酶的优化条件,考察了p H、戊二醛浓度、温度和时间四个变量对交联结果的影响。综合分析各实验小组的实验结果显示:酸性条件交联有利于酶活力及稳定性的保持;使用0.5%或更低的戊二醛浓度有利于酶活力的保持,但其稳定性提升不明显;较高温度下交联不利于酶活力的保持及稳定性的提升;随着交联时间的增加酶活力损失逐渐变大,但其使用稳定性却有所提升。     

海藻酸铝固定化糖化酶特性研究

采用海藻酸铝固定化糖化酶,对固定化酶和游离酶的特性进行了比较。结果表明,固定化酶米氏常数Km为13.72 mg/mL,最适温度为65℃,半衰期为100.7 d,固定化糖化酶的活力回收率达61.8%。