产淀粉酶非酿酒酵母菌的筛选及产酶特性研究

通过对非酿酒酵母菌的筛选鉴定,共得到11株产淀粉酶菌株,酶学性质研究表明,该11株酵母菌在pH值为7~9时表现了较高的酶活力,在pH值为5~6时保持稳定;最适反应温度为40℃,在30~50℃时保持较高酶活力;金属离子依赖性发现,Fe2+、Mg2+对酶有不同程度的激活作用,Ca2+、Ba2+、Cu2+对酶有抑制作用;十二烷基硫酸钠(SDS)、乙二胺四乙酸(EDTA)对酶均有抑制作用,EDTA抑制酶活约为50%,淀粉酶对二价金属离子具有一定的依赖作用。     

淀粉特性对馒头品质的影响

淀粉在馒头的发酵和熟化过程中有着不可替代的作用,馒头品质很大程度上受淀粉特性的影响。综述了小麦粉中淀粉含量、淀粉组成比例以及破损淀粉含量对馒头品质的影响,为馒头粉的生产和选购提供理论指导。     

豆瓣发酵瓣子中淀粉酶高产菌株的筛选及其酶活力的测定

以郫县豆瓣不同时期发酵瓣子为原料筛选淀粉酶高产菌株,利用淀粉酶水解圈作为筛选模型,通过筛选培养及酶活力的测定,得到产淀粉酶活力相对较高的菌株DD23,为80.24 IU/mL。通过菌落形态观察、生理生化鉴定和16S rDNA序列分析,确定DD23为蜡样芽胞杆菌（Bacillus cereus）。     

Phytochemicals and heavy metals content of hairless canary seed: A variety developed for food use

Canary seed is one of the top four specialty crops grown in Western Canada. Currently it is used entirely in food mixtures for caged birds but our previous studies have shown its unique composition and potential use in food and non-food applications. Through improvements by plant breeding a hairless variety was developed for human consumption and animal feeding. This study was aimed at investigating phytochemicals and heavy metals in hairless canary seed in comparison with the hairy variety and common wheat using three milling fractions (wholegrain, starchy flour and bran). The levels of bound and unbound phenolic acids, phytate, trypsin and amylase inhibitors tended to be similar in the three grains at a given level of processing. This was also true for most heavy metals tested although hairy canary seed exhibited a significantly higher concentration of copper while both canary seed varieties contained more nickel and zinc than wheat. Condensed tannins, alkaloids and deoxynivalenol (DON) were not detected in any of the crops while very low levels of aflatoxin were detected in all three grains. The results show that both hairless and hairy canary seed possess phytochemicals and heavy metals profile close to that of wheat demonstrating the potential of hairless canary seed as a food crop due to the absence of harmful hairs.     

Discovering Bisdemethoxycurcumin from Curcuma longa rhizome as a potent small molecule inhibitor of human pancreatic α-amylase,a target for type-2 diabetes

Curcuma longa rhizome is used extensively in culinary preparations in Far East and South-East Asia. Health benefits of curcuminoids from C. longa as antioxidants, anti-cancer and anti-inflammatory molecules have been well documented. We report here for the first time that Bisdemethoxycurcumin (BDMC) from C. longa, acts as an inhibitor to inactivate human pancreatic α-amylase, a therapeutic target for oral hypoglycemic agents in type-2 diabetes. Bioactivity guided isolation of rhizome isopropanol extract led to the identification by HPLC and NMR of BDMC as a lead small molecule inhibitor of porcine and human pancreatic α-amylase with an IC₅₀ value of 0.026 and 0.025 mM, respectively. Kinetic analysis revealed that using starch as the substrate, HPA exhibited an uncompetitive mode of inhibition with an apparent K_i of 3.0 μM. The study gains importance as BDMC could be a good drug candidate in development of new inhibitors of HPA and of functional foods for controlling starch digestion in order to reduce post-prandial hyperglycemia.     

Development of a submerged culture method for high production of acid‐ stable α‐amylase and glucoamylase using Aspergillus kawachii without glucose concentration control

It is commonly accepted that maintaining a low glucose concentration in a culture is an important condition for high level of production of acid‐stable α‐amylase (ASAAase) and glucoamylase (GAase) in submerged culture using Aspergillus kawachii. Raw materials with hard husks, such as barley, are able to control the release of glucose from the raw material and maintain a low glucose concentration, thereby enabling a high production of enzymes. On the other hand, it is difficult to produce large quantities of enzymes by controlling glucose release using raw materials without hard skins. This study evaluated a culture method for high enzyme production using raw materials without hard skins, such as a sweet potato, and found that this was possible using a moderately high concentration of sweet potato. Maximum ASAAase and GAase activities were 51 units/mL and 188 units/mL, respectively, both values being sufficiently high for potential industrial use. Glucose concentration remained high over time in the culture, suggesting that other mechanisms may be mediating the increase in enzyme production, despite the impact of medium glucose concentration on enzyme production. Copyright © 2013 The Institute of Brewing & Distilling     

潜在的水体修复菌Bacillus subtilis H001的筛选及其高密度培养

在水产养殖规模日益扩大和集约化程度不断提高时,带来了养殖水体富营养化、亚硝酸盐超标、致病微生物等问题,在其中引入益生菌,可起到预防和控制的作用。从10株枯草芽孢杆菌中,筛选出菌株H001具有较高淀粉酶和蛋白酶酶活,分别为36.7U/mL和35.6U/mL。当麸皮浸汁为40g/L,玉米浸汁为15g/L,豆粕为20g/L,H001菌落总数(TCN)对数值分别为12.1,12.1和14.0。当玉米浸汁与豆粕粉质量比为2:1时,麸皮浸汁与豆粕粉的质量比为2:1时,H001的TCN对数值都约为15.0。在模拟水体中,当亚硝酸盐含量分别为5.0mg/L、10.0mg/L、20.0mg/L、30.0mg/L、40.0mg/L和50.0mg/L时,菌株H001对其降解率分别为95.0%、95.0%、84.1%、68.6%、48.5%和44.4%。综上所述,具有较高淀粉酶和蛋白酶酶活的枯草芽孢杆菌H001,其培养基经优化后TCN提高到1.6×1015CFU/mL,优化后培养基组合经济且适合于H001的高密度培养,H001是一种潜在的养殖水体修复菌。     

Screening grape seeds recovered from winemaking by‐products as sources of reducing agents and mammalian α‐glucosidase and α‐amylase inhibitors

Grape seeds collected from vinification of various grape varieties were extracted by supercritical CO₂ for oil recovery. The defatted residues thus obtained were considered as a re‐utilisable co‐product and assessed for phenolic content, reducing capacity and inhibitory activities against mammalian α‐amylase and α‐glucosidase enzymes. Supercritical CO₂ treatment led to higher recovery of anthocyanins. Reducing capacity of phenolic extracts reached up to ~2200 mmolFe(II) kg^?1, much higher than that of various natural phenolic sources. The anthocyanin‐rich extracts showed the highest inhibitory effectiveness towards α‐glucosidase (I₅₀ value equal to ~40 μg gallic acid equivalents (GAE)/mL ~ half than acarbose). Inhibitory effectiveness towards α‐amylase activity was similar among grape varieties, with I₅₀ values comparable to that of acarbose and correlated with proanthocyanidin contents. These results could pave the way for an efficient processing of grapes, including cascade processes, namely: winemaking, oil extraction from recovered grape seeds and phenolic extraction from defatted grape seeds as potential cost‐effective nutraceuticals.     

紫甘薯β-淀粉酶提取纯化及稳定性的研究

对紫甘薯β-淀粉酶的稳定性进行了研究。结果表明紫甘薯β-淀粉酶在40～50℃有较好的热稳定性;在pH 5.0～7.0时有较好的稳定性,该酶对酸的耐受性相对较强而对碱的耐受性较弱。     

酸性淀粉酶菌株的诱变选育及酶学性质研究

为了筛选酶活力较高的酸性酶淀粉酶菌株,多次采用紫外（UV）、化学诱变剂硫酸二乙酯（DES）,对黑曲霉（ATCC-1602）进行处理,通过淀粉透明圈的大小快速检测出酶活力较高的菌株,再经固态发酵测定酶活,筛选出一株酶活力较高的菌株（ATCC-1694）,酶活力为394.1u/g,比原始菌株酶活力提高10倍。该酶最适温度为75℃、最适pH为4.0。在50℃、pH4.0条件下酶活力相当稳定,在酿造工业有良好的应用前景。