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排序方式: 共有504条查询结果,搜索用时 19 毫秒
1.
一株芝麻香型白酒高温大曲细菌Q2B1的鉴定及其产酶活性研究 总被引:1,自引:0,他引:1
大曲细菌关系到白酒酿造的品质,其中酶的含量与活性与白酒的风味紧密关联。以芝麻香型白酒高温大曲优势细菌代表菌株Q2B1为研究对象,利用分子生物学技术对其分类学地位进行研究,并通过全基因组研究技术对产酶相关功能基因与代谢通路进行研究。结果表明,菌株Q2B1被鉴定为贝莱斯芽孢杆菌(Bacillus velezensis)。利用传统的培养技术定性定量地检测其酶活力,发现菌株Q2B1可产淀粉酶和蛋白酶,活力分别为5.852 U/mL和26.770 U/mL;其产酶相关功能基因组长度为3 475 602 bp,包括蛋白酶编码基因以及淀粉酶编码基因,在基因水平上初步揭示了Q2B1菌株合成蛋白酶和淀粉酶的分子机理,为进一步合理开发白酒大曲微生物奠定理论基础,为提高白酒品质提供科学依据。 相似文献
2.
Zuming Li Zhihui Bai Deliang Wang Wujiu Zhang Michael Zhang Francis Lin Liping Gao Bodi Hui Hongxun Zhang 《International Journal of Food Science & Technology》2014,49(3):776-786
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. 相似文献
3.
Changes of porcine pancreas α‐amylase in activity and secondary conformations under inhibition of tea polyphenols 下载免费PDF全文
Shumin Liu Shiyi Ou Huihua Huang 《International Journal of Food Science & Technology》2016,51(6):1537-1543
To investigate two‐sided functions of tea polyphenols (TP) in antinutrition and energy balance modulation, TP were extracted from Chinese green tea and used to complex porcine pancreas α‐amylase (PPA). Changes of PPA in activity and secondary conformations were analysed. Porcine pancreas α‐amylase was found sensitive to TP treatment. Tea polyphenols exhibited IC50 at 0.41 mg mL?1 against PPA and maximum inhibitory rate (98.17%) at 3.0 mg mL?1. Tea polyphenols inhibition was concluded as noncompetitive pattern based on its unchanged Km value (0.98 mg mL?1) for soluble starch substrate. Tea polyphenols inhibition arose from pH 1.5 to 10.14, covering gastric and intestinal environments inside body. Circular dichroism spectra analysis revealed regular changes of PPA in secondary conformations (increased proportions of α‐helix and β‐sheet) prior to its inactivation at low TP concentrations. Tea polyphenols‐inhibited PPA had distinct double‐negative peaks at 204 nm and 208 nm. Porcine pancreas α‐amylase was inactivated by TP in ways of complexation and modification of secondary conformations. 相似文献
4.
Extraction,optimisation and characterisation of phenolics from Thymus vulgaris L.: phenolic content and profiles in relation to antioxidant,antidiabetic and antihypertensive properties 下载免费PDF全文
Muhammad H. Alu'datt Taha Rababah Ayman Johargy Sana Gammoh Khalil Ereifej Mohammad N. Alhamad Mary Susan Brewer Abdullah A. Saati Stan Kubow Mervat Rawshdeh 《International Journal of Food Science & Technology》2016,51(3):720-730
The objectives of this study were to examine varying extraction conditions of Thymus vulgaris L. as related to phenolic content and profiles of the extracts and their antioxidant, antihypertensive and antidiabetic properties. Phenolics were extracted under various conditions pertaining to free and bound phenolics, solvent type and combination of extraction time and temperature, and these extracts were evaluated in terms of their antioxidant activities and inhibitory activities of angiotensin‐converting enzyme (ACE), α‐glucosidase and α‐amylase. The acetone–water solvent mixture (1:1; v/v) produced the extract with the greatest phenolic content, antioxidant activity and inhibitory activities of ACE and α‐glucosidase. The optimal extraction temperature for maximum phenolic content and antioxidant activity associated with methanol extraction was 60 °C, whereas a lower temperature at 40 °C was required to maximise inhibitory activities for ACE, α‐glucosidase and α‐amylase. An inverse relationship was seen between antioxidant and glucosidase inhibitory activities vs. the ACE and α‐amylase inhibitory activities, which suggests the need for extractions to be directed to specific bioactivities of thyme extracts. Generally, the results indicate major differences in phenolic profiles among the tested extraction conditions with thymol as the predominant phenolic seen in most extractions, while gallic acid, rosmarinic acid or diosmin also predominated in other extracts. Extracts with the same predominant phenolic compound and similar phenolic content showed major disparities in their ACE, glucosidase and α‐amylase inhibitory activities, indicating that the major phenolic profiles of thyme extracts may not be necessarily related to the degree of inhibition of ACE, glucosidase and α‐amylase enzymes. 相似文献
5.
Influences of pretreatment and drying methods on composition,micro/molecular structures and some health‐related functional characteristics of dietary fibre powder from orange pulp residues 下载免费PDF全文
Sirada Sungsinchai Chalida Niamnuy Attasak Jaree Sakamon Devahastin 《International Journal of Food Science & Technology》2017,52(10):2217-2229
Influences of pretreatment methods (washing, blanching, soaking in ethanol), drying methods (hot air‐drying, infrared‐drying, microwave‐drying) and drying temperature on selected characteristics of dietary fibre powder from orange pulp residues were investigated. Pretreatments improved the hydration properties, oil‐holding capacity and glucose dialysis retardation index, but led to losses of fibres, decreased α‐amylase inhibitory activity and aflatoxin B1 adsorption capacity. Hydration properties, oil‐holding capacity and glucose uptake depended on the structure and porosity of the fibre, while the ability to inhibit α‐amylase and AFB1 adsorption depended more on the content and molecular fingerprinting of the fibre. Drying condition did not significantly affect functional properties of the fibre, except for the ability to uptake glucose, inhibit α‐amylase and adsorb AFB1 (P ≤ 0.05). Hot air‐drying at 60 °C resulted in fibre with the highest ability to decrease the rate of glucose and AFB1 adsorption. 相似文献
6.
Yen‐Hsu CHEN Wu‐Chang YANG Feng‐Ming WANG Der‐Cherng TARNG Jinn‐Yang CHEN Yee‐Yung NG Tsai‐Hun WU Yao‐Ping LIN Chih‐Ching LIN 《Hemodialysis international. International Symposium on Home Hemodialysis》2011,15(1):79-86
Elevated levels of serum pancreatic enzymes are frequently observed in hemodialysis (HD) patients. The complex hemodynamic, biochemical, and physiological alterations in uremia were speculated to cause excessive release of pancreatic enzymes beyond decreased renal clearance. However, hemodynamic factors are seldom explored in this aspect. We performed the study to evaluate the association between intradialytic hemodynamic change and elevated serum pancreatic amylase (SPA). Eighty‐three prevalent HD patients without any clinical evidence of acute pancreatitis underwent pre‐HD and post‐HD blood sampling for serum pancreatic enzyme levels. Demographic, biochemical, and hematological data were collected from patient record review. Hemodialysis information including intradialytic blood pressure changes and ultrafiltration (UF) amount were collected and averaged for 1 month before the blood sampling day. Patients with elevated SPA during the HD session had greater mean systolic blood pressure and mean arterial pressure reduction, greater UF volume, greater pre‐HD blood urea nitrogen and serum creatinine, higher serum phosphorus, lower pre‐HD serum total CO2, and lower left ventricle ejection fraction (LVEF). Using multivariate linear and logistic regression analysis, the independent predictors of elevated SPA were determined to be mean arterial pressure reduction during HD, mean UF amount, pre‐HD serum total CO2, and LVEF. Greater blood pressure reduction during HD, greater UF volume, lower pre‐HD serum total CO2, and lower LVEF were significantly associated with elevated SPA during HD. This suggests that hemodynamic factors contribute to elevated serum pancreatic enzymes in HD patients. 相似文献
7.
Catherine Grard Paul Colonna Alain Bulon Vronique Planchot 《Journal of the science of food and agriculture》2001,81(13):1281-1287
Starches from single and double maize mutants were subjected to enzymatic degradation by porcine pancreatic α‐amylase. The maize mutants covered a broad range of macromolecular composition and crystalline structure relative to fractional crystallinity level (from 0.19 to 0.48) and polymorphic type (with various proportions of A‐, B‐ and V‐type allomorphs). Regardless of amylose content or crystallinity level, starches with a predominant B‐crystalline type were more resistant to amylolysis than others, and initial rates of hydrolysis were lower for B‐type than A‐type starches. Final hydrolysis extents were less than 35% for predominant B‐type starches, 60% for C‐type ones and more than 70% for predominant A‐ or V‐type ones. Dangling chains or crystal defects also appeared to increase initial hydrolysis rates, although lower initial rates and final hydrolysis extents were mainly related to the amount of B‐type crystallites. Unexpectedly, hydrolysis residues were composed of both amorphous and B‐type crystalline regions. These observations suggest that resistance to amylolysis is related to the distribution of B‐type crystallites within the granule rather than to the relative proportion of B‐type crystallites. © 2001 Society of Chemical Industry 相似文献
8.
Yu Zheng Haiyi Zhang Li Zhao Liujing Wei Xingyuan Ma Dongzhi Wei 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(10):1409-1412
BACKGROUND: 2,3‐Butanediol (2,3‐BD) is a valuable chemical that can be biosynthesized from many kinds of substrates. For commercial biological production of 2,3‐BD, it is desirable to use cheap substrate without pretreatment, such as starch. However, there have been few reports on the production of 2,3‐BD directly from starch. RESULTS: In this work, gene malS coding for α‐amylase (EC 3.2.1.1) precursor was inserted into plasmid pUC18K, and secretory over‐expression of α‐amylase was achieved by engineered Klebsiella pneumoniae. The extracellular recombinant amylase accelerated the hydrolyzation of starch, and one‐step production of 2,3‐BD from starch was carried out by engineered K. pneumoniae. A 2,3‐BD concentration of 3.8 g L?1 and yield of 0.19 g 2,3‐BD g?1 starch were obtained after 24 h fermentation. CONCLUSION: The one‐step production of 2,3‐BD from starch was achieved by secretory over‐expression of amylase in K. pneumoniae. This would simplify the process and reduce the production cost considerably by enabling use of starch with minimal pretreatment. Copyright © 2008 Society of Chemical Industry 相似文献
9.
Microchip electrophoresis has recently attracted much attention in the field of nuclear acid analysis due to its high efficiency, ease of operation, low consumption of samples and reagents, and relatively low costs. In addition, the analysis has expanded to analytical fields, including the analysis not only of DNA but also of RNA, proteins, sugar chains, cellular functions, etc. In this paper we describe the creation of high‐performance monitoring systems for human blood glucose levels and α‐amylase activity in human plasma using microchip electrophoresis. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 177(1): 19–25, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21158 相似文献
10.
KS Atia SA Ismail AM Dessouki 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2003,78(8):891-898
Barley β‐amlyase was immobilized on two polymeric materials; poly(acrylamide–acrylic acid) resin [P(AM‐AAc)] and poly(acrylamide–acrylic acid–diallylamine–HCl) resin [P(P(AM‐AAc‐DAA‐HCl) using two different methods: covalent and cross‐linking immobilization. Thionyl chloride, used to activate the polymers for covalent immobilization, has the advantage that it is able to react with a number of surface groups of protein under very mild conditions. Cross‐linking with glutaraldehyde gave a higher coupling yield (approximately 70%) than covalent immobilization (approximately 20%). The activity and stability of the resulting biopolymers have been compared with those of free β‐amylase. The specific activity of the immobilized enzyme was significantly influenced by the amount of enzyme loaded onto the polymers, the optimal level being 3.5 mg g?1 polymer. It was found that the immobilized β‐amylase stored at 4°C retained approximately 90% of its original activity after 30 days, whereas free β‐amylase stored in solution at 4°C retained only 47% of its activity after same period. The difference in long term stability was more significant when the enzyme was stored at room temperature; the immobilized enzyme maintained 40% of its activity after 30 days, whereas the residual activity of free enzyme was only 10%. Copyright © 2003 Society of Chemical Industry 相似文献