液体曲制酒精研究的回顾

本文回顾了我国液体曲制酒精研究的历程。上世纪五十年代,上海和其他地区相继组织了研究团队开展液体曲生产酒精的研究,上海研究团队进行了大量的研究,作者曾亲历并参与其中。研究内容包括糖化酶活力测试、菌种筛选、培养基和培养条件的优化以及中试放大试验。几经努力,终于成功开发出液体曲,淘汰了落后陈旧的麸曲工艺,最终实现了液体曲在酒精生产上的应用。由于在液体曲研发阶段引入了抗生素生产的深层培养技术,使酒精发酵实现了机械化和自动化,这为随后的氨基酸以及其他产品的发酵生产打下了良好的基础。

New amperometric glucose biosensor by entrapping glucose oxidase into chitosan/nanoporous ZrO_2/multiwalled carbon nanotubes nanocomposite film

A new nanocomposite material for construction of glucose biosensor was prepared. The biosensor was formed by entrapping glucose oxidase(Gox) into chitosan/nanoporous ZrO2/multiwalled carbon nanotubes nanocomposite film. In this biosensing thin film, the multiwalled carbon nanotubes can effectively catalyze hydrogen peroxide and nanoporous ZrO2 can enhance the stability of the immobilized enzyme. The resulting biosensor provides a very effective matrix for the immobilization of glucose oxidase and exhibits a wide linear response range from 8 μmol/L to 3 mmol/L with a correlation coefficient of 0.994 for the detection of glucose. And the response time and detection limit of the biosensor are determined to be 6 s and 3.5 μmol/L, respectively. Another attractive characteristic is that the biosensor is inexpensive, stable and reliable.

Macroalage as a source of alpha-glucosidase inhibitors

Alpha-glucosidase inhibitors were screened from organic solvent extracts of macroalgae by a spec- trophotometrical method with p-nitrophenyl-D-glucopyranosidase as the substrate. The result indicates that or- ganic crude extracts from some macroalgae such as Rhodomela confervoides (Huds.) Silva, Gracilaria textorii (Suringar) DeToni, Plocamium telfairiae Harv., Dictyopteris divaricata (Okam.) Okam, Ulval pertusa and En- teromorpha intestinalis (L.) Link et al. show strong inhibitory activity of alpha-glucosidase at concentration of 79.6 μg/ml.

Production of Amylase from Saccharomyces diastaticus sp. and Hydrolysis of Cassava Pulps for Alcohol Production

Amylolytic enzymes are currently investigated to improve industrial processes of starch degradation. Saccharomyces diastaticus 2047 isolated from cassava waste showed amylase and glucoamylase production, using starch medium, and the highest rate was obtained in the initial growth phase, after incubation for 24 h at pH 5.5. Maximum amylase and glucoamylase activities （483.62 U mg^-1 protein and 290.85 U mg^-1 protein） were obtained at pH 5.5. The isolated enzymes exhibited thermostable properties as indicated by retention of 100% of residual activity at 55 ℃ for 45 min with total inhibition at 100 ℃. Extracellular enzyme from S diastaticus 2047 was partially purified by fractionated precipitation with ammonium sulphate. After 40% saturation produced 2,197.00 and 1,192.83 U/mg protein, and yield was 40% with purification 4.54 and 4.1 fold, respectively. This study presents feasibility on ethanol production from cassava pulps pretreated with diluted sulfuric acid by simultaneous saccharification and fermentation （SSF） with S. diastaticus 2047. The results indicated that the culture was able to produce ethanol with high yield without amylolytic enzyme adding by using cassava pulps pretreated with distilled water at 135 ℃ under pressure of 15 lb/inch^2 to produce ethanol yield as high as the cassava pulps pretreated with diluted sulfuric acid under the same condition. This suggests that S diastaticus with enzyme produced has potential for industrial applications.

Kinetic Parameter of Alfa-amylase and Glucoamylase Enzymatic Reaction on the Glucose Yield from Hydrolyzed Processes of Tapioca Solid Waste

The increasing of tapioca production nowadays effected the production of waste. The waste of tapioca industries consists of two kinds, which were liquid waste and solid waste. Further more, tapioca solid waste treatment was ineffective. Weather solid waste produced from the extraction process still contains high concentration of starch that can be used to produce high quality product, for example, bio ethanol or other alternative energy sources. Objective of these experimental work was utilizing solid waste of tapioca industries and looking for the exactly composition of n-amylase and gluco-amylase enzymes on the hydrolysis processes of the solid waste of tapioca. The exact composition from both enzymes can be expected to increase the yield of glucose. Variables of cx-amylase enzyme for this research were 0.3% （w/w） and 0.5% （w/w） with liquefaction time were 1 hour and 1.5 hours, and variables of glucoamylase enzyme were 0.3% （w/w） and 0.5% （w/w）. To achieve these goals, the experimental work was held in laboratory scale with batch process. Firstly, tapioca solid waste was pretreated at 90 ~C and added u-amylase enzyme for 1 hour and 1.5 hours （variable of liquefaction time）. Then, substrate was cooled down to 60 ~C added with proposed variables of glucoamylase enzyme, and was analysed 24 hours after added. This experiment showed the best ratio between a-amylase and glucoamylase enzymes 0.5%：0.5% with 1 hour of liquefaction time. The highest glucose reaches 8.468% and yields 0.892 （g glucose/g starch） with starch conversion of 59.94%. KM = 0.0468 g/mL and rmax = 0.311 g/mL·h,

Electrochemiluminescence glucose biosensor based on glucose dehydrogenase functionalized Ru(bpy)_3^(2+) doped silica nanoparticles

A novel electrochemiluminescence (ECL) sensing approach was developed for glucose detection based on crosslinking Ru(bpy)3Cl2-doped silica nanoparticles (RuSiNPs) with glucose dehydrogenase on a glassy carbon electrode (GCE). Glutaral- dehyde and aminopropyltrimethoxysilane were used as linking agents, and chitosan was used to immobilize the composites onto the GCE surface. The ECL sensor presented good characteristics in terms of stability and reproducibility. Under opti- mized conditions, the linear response of ECL intensity to glucose concentration was valid in the range of 0.2 to 20 mmol/L (R2 = 0.9962). The application results indicated that the proposed approach is with great potential in the determination of glucose.

In vitro antioxidant activity and potential inhibitory action against α-glucosidase of polysaccharides from fruit peel of tea(Camellia sinensis L.)

The conditions for extracting polysaccharides from tea （Camellia sinensis L.） fruit peel （TFPPs） were studied. Three parameters （temperature, time, and liquid/solid ratio） affecting the extraction of TFPP were optimized using response surface methodology （RSM）. Under the optimized conditions, the yield of TFPP was predicted to be 4.98%. The physicochemical properties, in vitro antioxidant activities, and inhibitory effects on α-glucosidase of frac- tionated TFPPs （TFPP-0, TFPP-20, TFPP-40, and TFPP-60） were investigated. We found that the TFPPs were all acid protein-bound heteropolysaccharides, although with different chemical compositions. They had not only re- markable scavenging activity on 2,2＇-azinobis（3-ethylbenzothiazoline-6-sulfonic acid） diammonium salt （ABTS） and reducing activity, but also excellent inhibitory potential against α-glucosidase in vitro. Our results suggest that tea fruit peel could be treated as a potential bioresource for the development of polysaccharide antioxidants.

A glucose biosensor based on direct electrochemistry of glucose oxidase immobilized onto platinum nanoparticles modified graphene electrode

The platinum nanoparticles were adsorbed on graphene oxide sheets and played an important role in catalytic reduction of graphene oxide with hydrazine, leading to the formation of graphene-Pt nanoparticles. Because of their good electronic properties, biocompatibility and high surface area, graphene-Pt based composites achieved the direct electron transfer of redox enzyme and maintained their bioactivity well. The graphene-Pt nanocomposites were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM) and selected area electron diffraction (SAED). The amperometric biosensor fabricated by depositing glucose oxidase over Nafion-solubilized graphene-Pt electrode retained its biocatalytic activity and has offered fast and sensitive glucose quantification.