新型耐酸性液化糖化酶的分离提取及其特性

白曲霉基因工程菌TR12在液体培养基中32℃摇瓶培养96h，粗提酶液经进一步分离提取，得到同时具有液化和糖化两种酶活力的新型酶制剂，最适PH值为4．6。耐酸性α—淀粉酶活性的最适温度为60℃，糖化酶活性的最适温度为50℃。在pE54．6酸性条件下，该液化糖化酶在50℃保温1h，仍具有原酶活性。Ca^2 对该耐酸性液化糖化酶有激活作用，Fe^3 、Ak^3 等金属离子对该酶活力有一定的抑制作用。     

添加淀粉酶改进低发芽率麦芽酿酒质量

以低发芽率麦芽为原料，通过添加淀粉酶，采用一次煮出糖化法生产啤酒．糊化锅温度为７０℃，添加α－淀粉酶１．０‰，糖化锅温度为６３℃，添加β－淀粉酶４．０‰，生产出的啤酒符合ＧＢ４９２７－９１（一级）质量标准．     

影响泸型大曲淀粉酶活力测定结果的因素探讨

主要对泸型大曲淀粉酶活力测定过程中，温度、过滤方法、淀粉浓度和定糖吸样量对大曲糖化力的影响；热处理温度、过海方法、缓冲液的加入与否和终点判定标准等对大曲液化力的影响。     

松香基功能高分子稀土离子配合物固定化淀粉酶

分别以聚马来松香己二醇酯、马来松香乙二醇丙烯酯聚合物和马来松香乙二醇丙烯酯- 丙烯酸共聚物为载体,稀土离子为桥键配离子固定化淀粉酶。测定固定化淀粉酶的性能,探讨固定化酶反应机理。结果表明,稀土离子作为桥键配离子的固定化淀粉酶中,PMGAE Y(III)En 和PMGAEDy(III)En 效果较好;最适宜温度均为60℃,最适宜pH 值均为6.03;重复使用4 次后,活性分别为31.49、29.76mg/g·5min。此外,建立了固定化酶活性与功能高分子微孔面积及酸值间的数学关系式。     

PS0312 菌株发酵产淀粉酶及温度与pH 值对酶活力的影响

PS0312 菌株是具有特殊生物学特性的青霉菌株。以三角瓶固体培养研究不同条件与菌株产淀粉酶的关系,以及温度与pH 值对酶活力的影响。结果表明：PS0312 菌株以麸皮30.04%、大豆饼粉3.70%、谷壳3.70% 及55.56% 蒸馏水组成的培养基固体发酵湿麸曲淀粉酶产量最高。单因子试验结果表明：以培养基pH3、108 个/mL的种子液接种量1.85%、培养温度28℃、培养时间96h 产淀粉酶量最大。PS0312 菌株产淀粉酶在pH2.0～10.0 内具较高活性,酶活大小与pH 值的关系成双峰形;pH3 的条件下酶活性最高,相对酶活100%;pH9 的条件下酶活次之,相对酶活84.98%。酶反应最适温度为60℃,90℃条件下相对酶活为39.06%。研究表明：PS0312 菌株发酵产淀粉酶是一种在强酸、强碱条件下都具有较高的酶活性和耐高温的特殊的酸性、中温淀粉酶,可在较宽的温度与pH 值范围下应用。     

鲫鱼肠道细菌菌群初步分析

从健康鲫鱼肠道分离出62 株细菌菌株,革兰氏染色分析结果表明,其中18 株为革兰氏阳性菌株,44 株为革兰氏阴性菌株。实验分析各菌株产纤维素酶和产淀粉酶的情况。筛选到26 株产淀粉酶菌株,占筛选菌株的41.94%,没有从鲫鱼肠道内筛选到产纤维素酶菌株。使用16S rDNA 基因序列检测,确定相关菌株分别属于Aeromonas、Shewanella、Pseudomonas 等。分析产酶活性较高的菌株F2 的致病性和产酶活力,确定其不是鲫鱼致病菌,其分泌性淀粉酶在pH7、温度32℃时表现出最大酶活力。     

Enzymatic synthesis of glycosylated puerarin using maltogenic amylase from Bacillus stearothermophilus expressed in Bacillus subtilis

BACKGROUND: The maltogenic amylase from Bacillus stearothermophilus (BSMA) is a valuable biocatalyst that has been used to transglycosylate natural glycosides to improve solubility. To ensure safety, BSMA was produced in Bacillus subtilis, using new shuttle vector‐based expression vectors. The transglycosylation of puerarin was also conducted with crude BSMA and analyzed. RESULTS: Two expression systems, each containing one of the promoters from the genes encoding Bacillus licheniformis maltogenic amylase (BLMA) and an α‐amylase from B. subtilis NA64 (amyR2), were constructed. The amyR2 promoter system was chosen as the best system; it yielded 107 mg of pure BSMA from a 2 L culture. In the transglycosylation reactions of puerarin using crude BSMA, relative amounts for maltosyl‐α‐(1 → 6)‐puerarin, glucosyl‐α‐(1 → 6)‐puerarin, glucosyl‐α‐(1 → 3)‐puerarin, and puerarin were determined as 26:18:7:49. A two‐step purification process, including gel permeation chromatography, yielded 1.7 g of the transfer products from 3 g of puerarin. CONCLUSION: The crude BSMA produced from a host generally recognized as safe (B. subtilis) can be used to transglycosylate various functional compounds. The expression system developed in this study will be helpful for the production of other food‐grade enzymes by B. subtilis. Copyright © 2010 Society of Chemical Industry     

酶法生产速溶慈姑粉的工艺研究

研究了速溶慈姑粉的生产工艺。采用L_9(3~4)正交实验研究了pH值、反应温度、酶添加量与反应时间对慈姑浆可溶性糖含量的影响,酶解后经喷雾干燥制得速溶慈姑粉。结果表明,其酶解工艺选择为:pH值6.0、水解温度60℃、α-淀粉酶和纤维素酶添加量分别为0.1%(g酶/g慈姑)和0.4%(g酶/g慈姑),反应时间80min。干燥后样品的润湿性、分散性、堆积密度和溶解性分别为56.17s、15.34s、0.5231 g/mL、89.63%。     

An evaluation of exogenous enzymes with amylolytic activity for dairy cows

An experimental (7B) and a commercial (AMA) formulation of enzymes, both primarily with α-amylase activity, were evaluated for activity at various pH values, stability in ruminal fluid, the potential to improve in vitro ruminal fermentations, and the potential to improve production performance of lactating cows. When incubated (40°C) in buffer with a pH between 5.4 and 6.0, 7B had about 10 to 25 times greater amylase activity than AMA, and enzyme activity in this range increased by 100% for 7B, whereas activity decreased by about 26% for AMA. Both formulations maintained enzyme activity when they were incubated in in vitro ruminal fermentations for 24 h. After 6 h of ruminal in vitro fermentation, additions of 7B resulted in linear increases in apparent total volatile fatty acid production for flint and dent corn but had no effect on floury corn. In a lactation trial, 28 Holstein cows (68 ± 31 d in milk, 46.9 ± 9.1 kg of milk/d) were fed a total mixed ration (TMR) supplemented with nothing (CON), a low dose of 7B [7BL, 0.88 mL/kg of TMR dry matter (DM)], a high dose of 7B (7BH, 4.4 mL/kg of TMR DM), or AMA (0.4 g/kg of TMR DM). The experiment was conducted as a 4. 4 Latin square design with 21-d periods. Cows fed 7BL, 7BH, and AMA ate similar amounts of DM, and cows fed the latter 2 diets consumed more DM than did cows fed CON. Cows fed 7BL produced more milk than cows fed CON and 7BH, but produced similar amounts to cows fed AMA. The production of 3.5% fat-corrected milk was greater from cows fed 7BL and AMA compared with cows fed CON. The percentages of milk fat and milk protein were unaffected by treatment. Total-tract digestion of DM and organic matter were greater for cows fed 7BL compared with those fed CON. The addition of exogenous amylase enzymes to the diets of lactating dairy cows has the potential to improve animal productivity.     

Protein interactions with cyanidin‐3‐glucoside and its influence on α‐amylase activity

BACKGROUND: Recent studies indicate that the bioavailability of anthocyanins is extremely low. One of the possible reasons could be their binding to proteins. Therefore, the binding affinity of cyanidin‐3‐glucoside (Cy3glc) to HSA and α‐amylase was investigated by the quenching of protein tryptophan fluorescence. From data obtained, the binding constants and the free Gibbs energy were calculated. The changes in conformation of the proteins tested were studied with circular dichroism and the influence of binding on α‐amylase activity determined. RESULTS: Cy3glc quenched the tryptophan fluorescence and upon ligand binding a change in protein structure was observed related to the corresponding decrease in the α‐amylase activity. The association constants of 25 to 77 × 10³ L mol^?1 were calculated for different proteins, indicating weak interactions of non‐covalent nature. Competitive binding with HSA in the presence of 8‐anilino‐1‐naphthalene sulfonic acid suggest involvement of hydrophobic interactions, in the case of HSA the possible site being subdomain IIA. CONCLUSION: The strongest affinity of Cy3glc for HSA being at pH 7 underlines its potential in transport and distribution of the phenolic compounds in organisms. An influence on salivary amylase activity is possible when drinking berry juices with high anthocyanins content. Copyright © 2008 Society of Chemical Industry