一株贝莱斯芽孢杆菌的生长特性及抑菌活性研究

从自然发酵海洋鱼酱油中分离得到了一株具有多种蛋白酶活性与糖酶活性的贝莱斯芽孢杆菌SW5菌株,为探究贝莱斯芽孢杆菌SW5的抑菌特性,研究了SW5菌株的生长及生理生化特性,验证了SW5菌株发酵上清液对食品中多种常见病原菌的抑制能力;并利用液相色谱-质谱联用技术鉴定了其中的抑菌物质.结果表明:菌株SW5在35℃、pH值5时生...     

三叶青茎部不同溶剂提取物的功能成分、抗氧化及酪氨酸酶抑制活性研究

目的 以三叶青茎部为原料,探究三叶青不同溶剂提取物的功能成分、抗氧化及酪氨酸酶抑制活性。方法 采用乙醇超声法提取三叶青,获得醇提液及残渣。醇提液依次用石油醚、乙酸乙酯、正丁醇对其进行分步萃取,残渣则采用蒸馏水多次提取,最终得到4种提取物。分别测定4种提取物总酚、总黄酮、总皂苷、总多糖、抗氧化及酪氨酸酶抑制活性,并进行相关性分析。结果 4种提取物中乙酸乙酯萃取物总酚、总黄酮、总皂苷含量最高,分别为40.22%±1.01%、38.56%±0.64%、6.15%±0.21%,正丁醇萃取物总多糖含量最高,为9.29%±0.25%。各萃取物均具有抗氧化和酪氨酸酶抑制活性,其中乙酸乙酯萃取物清除1,1-二苯基-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基、超氧阴离子、2-苯基-4,4,5,5-四甲基咪唑啉-3-氧代-1-氧(2-phenyl-4,4,5,5-tetramethylimidazoline-3-oxide-1-oxyl,PTIO)自由基、羟自由基能力和铁离子还原能力(ferric reducing antioxidant power, FRA...     

Three-liquid-phase salting-out extraction of effective components from waste liquor of processing sea cucumber

A three-liquid-phase (TLP) salting-out extraction system composed of n-hexane/ethanol/sodium carbonate/water was investigated to extract oils, saponins, proteins and polysaccharides simultaneously from waste liquor of processing sea cucumber. The effects of the ratio of ethanol to sodium carbonate, n-hexane concentration and extraction time were investigated. The results showed that 86.7% of oils were distributed in the top n-hexane phase, 82.9% of saponins in the middle ethanol phase, 93.2% of proteins and 92.9% of polysaccharides in the interface between the middle and the bottom salt phase when the system composed of 28% (w/w) n-hexane/11.52% (w/w) ethanol/8.64% (w/w) sodium carbonate was used at 37 °C for 0.5 h. When the system was progressively enlarged from 30 g to 25 kg, the yield of polysaccharides, proteins, oils and saponins was decreased only by 1.0%, 2.8%, 1.0% and 2.6%, respectively. The recycle of salt and solvents in three-liquid-phase system was also studied, and the results showed that the recovery of n-hexane, ethanol and salt were 81.4%, 80.8% and 72.0%, respectively. Recycling materials for the extraction, the yield for proteins and oils decreased by 2.0% and 5.4%, respectively, comparing with the pure system.     

谷物醇溶蛋白与植物多酚的互作机理及应用研究进展

谷物醇溶蛋白与植物多酚通常是食品基质中共存的两种重要成分,它们在食品的感官、功能特性和品质方面都起着关键作用。两者在食物体系中极易发生相互作用,从而影响两者的结构、功能属性以及生物利用度。本文首先讨论了谷物醇溶蛋白-植物多酚复合物的形成机制和影响因素,两者的相互作用包括非共价作用和共价作用,与其化学结构和制备复合物时所处的外部环境条件密切相关;然后讨论了两者相互作用对复合物功能属性的影响,包括对复合物乳化性、抗氧化活性和热稳定性的影响;最后综述了谷物醇溶蛋白-植物多酚复合物在乳液、薄膜和递送系统中的应用研究进展,以期为谷物醇溶蛋白和植物多酚的高值化利用、产品开发及在食品和相关领域的应用提供理论依据。     

黄鲫(Setipinna taty)蛋白酶解液的抑菌活性及稳定性研究

以黄鲫为原料测定其氨基酸组成,比较风味蛋白酶、胰蛋白酶、胃蛋白酶、碱性蛋白酶和木瓜蛋白酶水解黄鲫蛋白所得酶解液对大肠杆菌的抑菌作用,并对抑菌效果最强的蛋白酶酶解液进行抑菌稳定性研究。结果表明：黄鲫蛋白必需氨基酸含量丰富,其中胃蛋白酶的水解液对大肠杆菌抑菌作用强,相对分子质量主要分布在3000～1000;黄鲫胃蛋白酶酶解液对热稳定,酸性低pH值可增强其抑菌效果,可耐受胰蛋白酶和β-内酰胺酶处理,该酶解液有作为天然抗菌剂应用的前景。     

New microbiological catalytic accesses to (S)-fluoxetine

Saccharomyces cerevisiae, Hansenula sp., Dekera sp. and Kluyveromyces marxianus free and immobilized and free Geotrichum sp. have been used in the reduction of ethyl benzoylacetate yielding, in up to 99% ees, ethyl (S)-3-hydroxi-3-phenylpropionate, a suitable intermediate for the production of fluoxetine.     

Technological and hygienic consequences of reservoirs eutrophication in the Czech Republic

More than one half of drinking water demand in the Czech Republic is covered by surface water resources. The most frequent problems of the water treatment and supply are caused by the eutrophication of reservoirs. Biological parameters of drinking water quality based upon the microscopic analysis are included in local standards and commonly used in water works laboratories. Several new methods and criteria have been elaborated: microscopic evaluation of the separation efficiency of water treatment, categorization of microorganisms according to their separability, a screening bioassay for the assessment of biological stability of the water in course of the treatment and distribution, biological indicators of the eutrophication degree of reservoirs and their tributaries. A set of supplementary biological methods and criteria for special cases was published. Algal toxins have been detected not only in cyanobacterial water blooms in reservoirs but also in periphyton layers growing m different units of water works treatment trains. Two examples of the integrated system approach to the water supply from eutrophicated reservoirs inclusive of proposed preventive and remedial measures are selected from a recently finished extensive research project. Improvement actions in the resources protection, water works design and operation, laboratory control system and legislation are recommended.     

CO2 hydrogenation on Co/CeO2-δ catalyst: Morphology effect from CeO2 support

The Co/CeO_2-δ catalysts with different morphology structure were prepared for CO₂ catalytic hydrogenation reaction. The physical and chemical properties of these catalysts were characterized by H₂-TPR, XRD, TEM, ICP and H₂-TPD. The characterization results indicated that the different morphology structure of CeO₂ support obviously influence the exposed crystal plane, and then affect the concentration of oxygen vacancies, the metal-support interaction and the dispersion of Co⁰ active species on the CeO₂ support. In addition, the Co ions can be dissolved into the CeO₂ lattice to form Ce–O–Co solid solution, which promotes the formation of Co⁰ active species, oxygen vacancies, and the Ce³⁺-□-Co⁰ structure, thus significantly affects the CO₂ hydrogenation performance of Co/CeO_2-δ catalysts. The exposed {110} and {100} crystal plane of CoCe140 catalyst with nano-rods structure ensure the excellent CO₂ hydrogenation performance, including CO₂ conversion is 48.7%, the CH₄ and CO selectivity are 91.7% and 8.3%, respectively.     

Characterization and catalytic properties of nano-sized Pt metal catalyst on TiO2-SiO2 synthesized by photo-assisted deposition and impregnation methods

The photo-assisted deposition (PAD) and impregnation (img) syntheses of nano-sized Pt metal on TiO₂-SiO₂ are reported. The prepared catalysts were characterized by different techniques such as XRD, XAFS, TEM and nitrogen adsorption analysis. Photocatalytic reactivity using Pt-TiO₂-SiO₂ catalysts under visible-light condition for the oxidation of 2-propanol was evaluated. The results showed a notable photocatalytic activity of PAD-Pt-TiO₂-SiO₂ which was 1.5 and 4.7 times higher than that of imp-Pt-TiO₂-SiO₂ and TiO₂-SiO₂, respectively. Furthermore, PAD-Pt-TiO₂-SiO₂ catalysts exhibit a better catalytic property for hydrogenation of nitrobenzene, compared to the catalysts prepared by impregnation method.     

An improved method for the indexing of software

Many organizations are implementing free-text indexing schemes in order to build software catalogs with the aim of promoting systematic code reuse. Unfortunately, comments embedded in software systems suffer from several shortcomings, therefore it is not reasonable to pretend that the quality of the indices that can be extracted from them must be high. In the present empirical work, we implemented one such methods with the purpose of showing what could be expected when they are applied to the comments. The method we referred to uses pairs of words (called lexical affinities) as indexing units. The authors of such a method have given numerical indications (by carrying out a limited number of experiments on text-files about Unix commands) that lexical affinities provide better results than single-word schemes traditionally adopted in information retrieval. Our findings, arrived at by experimenting with such an indexing scheme over the comments of a large collection of commercial routines, account for our pessimism: only in 1.9% of the texts processed, the extracted indices are semantically representative of the purpose of the routines the comments were embedded in. A general strategy suitable to get better results is proposed in the second part of the article and evaluated against the same collection of routines.