谷氨酸发酵液絮凝除菌的研究

采用天然高分子聚合物壳聚糖为絮凝剂,对谷氨酸发酵液中菌体的絮凝作用及絮体处理进行了系统的研究,并进行了１０００１中间试验。结果表明,发酵液ｐＨ、壳聚糖用量是影响絮凝效果的主要因素。ｐＨ５．５～６．５,壳聚糖用量３０×１０^－３ｇ／ｌ,温度３０～３５℃,搅拌转速２０ｒ／ｍｉｎ,搅拌１～２ｍｉｎ,可获得良好的絮凝效果。１０００１中试结果,除菌上清液低温等电点提取谷氨酸收率８３％,谷氨酸纯度９１．３％,谷氨酸总收率８０．２６％。壳聚糖对谷氨酸发酵液和等电点母液中的菌体均有良好的絮凝作用。     

黄原胶发酵液纯化精制研究

溶剂法直接提取的黄原胶产品含有大量菌体蛋白和色素杂质,总氮含量高、透明度差、色泽暗深。通过中性蛋白酶处理发酵液,使成品含氮量下降５６．５％;通过Ｎａ２ＳＯ３漂白液,使产品色泽大为改善。实验得出最佳酶解条件：发酵液稀释１倍,温度４４℃、ｐＨ７,加酶量１００ｕ／ｇ发酵液,作用时间２．５ｈ;最佳Ｎａ２ＳＯ３漂白条件：温度２０￣３０℃,ｐＨ５￣６,Ｎａ２ＳＯ３用量为１％（ｗ／ｗ）,作用时间１￣１．５ｈ。     

洗涤剂用碱性纤维素酶的研究（Ⅱ）——酶的提取及性质

产碱性纤维素酶的嗜碱芽孢杆菌ＳＨＹ８－５７２５发酵液经絮凝预处理后,采用混合盐析方法沉淀酶,盐析收率可达９５％以上,所制得酶粉ＣＭＣａｓｅ可达５００ｕ／ｇ以上。酶的最适ｐＨ为８．０和１０．５,稳定ｐＨ范围为４～１２;最适温度为４５℃（ｐＨ９．０,１０ｍｉｎ）稳定温度范围为５０℃（ｐＨ９．０,３０ｍｉｎ）以下;洗衣粉中各种表面活性剂和助剂对ＣＭＣａｓｅ基本无影响,酶的底物特异性表明,该碱性纤维素酶主     

一株具有纤溶活性的枯草杆菌(Bacillus Subtilis)的研究——液体发酵条件的选择

本文主要报告了,以ＢａｃｉｌｕｓＳｕｂｔｉｌｉｓＨＷ－１２为试验菌株,在液体发酵中,所确定的发酵条件为：碳源是木糖,氮源是大豆胰蛋白胨,发酵液ｐＨ７．０,培养温度３７℃,培养时间９６小时。在这样的发酵条件下,该菌产酶活力为２００尿激酶单位／毫升发酵液 。     

金针菇菌丝体的深层培养及多糖制取

从２０株金针菇菌株中筛选出适于液体发酵的９４Ｂ２株。该菌种适宜的摇瓶培养条件：培养温度２３～２４℃,ｐＨ６．５,接液体种量１０％,装液量≤５０ｍｌ／５００ｍｌ瓶;不同的间歇振荡形式对菌丝球产量和形态有显著影响。深层发酵工艺相似于抗生素发酵。发酵期间发酵液ｐＨ变化幅度很小,总糖、还原糖、氨基氮与菌丝生长量有一定的相关性。发酵酵的菌丝产量可达４７．５ｇ（湿重）／１００ｍｌ、胞外多糖达１７４．７ｋｇ／１００ｍｌ发酵液上清、胞内多糖达３３８．１ｍｇ／１００ｇ湿菌丝体。     

细菌乳酸脱氢酶的纯化及其性质研究

从乳酸杆菌发酵液经过两次柱层析,可以得到纯度较高的乳酸脱氢酶,酶的比活力高达６７８．９ｕ／ｍｇ,纯度提高８５．７倍。酶的热稳定性好,ｐＨ稳定范围较宽,在临床上可用于雨氨酸氨基较移酶活力的测定。     

豆豉抗栓作用的研究

对豆豉提取物进行了哈白兔体内体外溶栓、抗凝试验,分别以蚓激酶和尿激酶按大、中、小剂量组作对照实验,均有显著的溶解血栓功能．另外,对豆鼓提取物纤溶活性、纤维蛋白溶酶原激活活性的测定及溶解天热血块、凝血时间影响的药理学试验,结果证明豆鼓提取物对家兔的动脉血栓形成有抑制作用和溶解血栓作用。     

纳豆激酶的原核表达、纯化及其特性分析（英文）

纳豆激酶(Nattokinase)作为一种新型溶解血栓的纤维蛋白溶解酶,有着广阔的市场前景和巨大的产业化潜力。本研究从枯草芽胞杆菌(Bacillus subtilis natto)发酵液中提取、纯化纳豆激酶,依次通过硫酸铵盐析、凝胶过滤层析和疏水层析方法纯化纳豆激酶,纯化倍数为5.2,纯化率为46.3%。纯化后的纳豆激酶经SDS-PAGE电泳显示相对分子量约为28 kD a,纤维蛋白平板法显示活性为4 580 IU/mg。但纳豆激酶在枯草芽胞杆菌发酵液中的含量较低,因此在原核表达载体大肠埃希菌(Escherichia coli)BL21(DE3)中克隆并高效表达了纳豆激酶基因,其纳豆激酶产量显著提高,但酶活相对降低。     

中温碱性脂肪酶的研究：Ⅲ.扩展青霉PF868变株碱性脂肪酶的纯化及其…

扩展青霉ＰＦ８６８变株发酵液经硫酸铵盐析和Ｓｅｐｈａｄｅｘ－Ｇ－２００及Ｓｅｐｈａｒｏｓｅ４Ｂ柱层析纯化,获得纯化倍数为３２．４的酶粉。该酶分子量为２３４４２Ｄａｌ,酶学特性表明：该酶的最适作用温度为３２℃,５０℃保温３０ｍｉｎ仍保留５０％酶活性,最适ｐＨ为９．０,作用ｐＨ稳定范围在７．０－１０．０之间,Ｃａ＾２＋和Ｍｇ＾２＋对酶有激活作用,Ｆｅ＾２＋,Ｃｕ＾２＋和Ｍｎ＾２＋酶活力有抑制作用。     

温度和pH对B.s.C3—41菌株生长和毒力的影响

本文报道了不同培养温度和液体培养基的起始州值对球形芽孢杆菌Ｃ３－４１菌株的生长和毒力的影响绪果。在２０－４０℃下分别进行摇瓶发酵实验时,以３５℃下培养的发酵液菌数最高,杀蚊毒力最强,其生长周期最短;当将液体培养基ｐＨ分别调至５、６、７、８、９、１０在３０℃以２２０ｒ／ｍｉｎ进行摇瓶发酵时,证明在ｐＨ７下培养的发酵液毒力最强。     

Purification and some enzymatic properties of the chitosanase from Bacillus R-4 which lyses Rhizopus cell walls.

A strain of Bacillus sp (Bacillus R-4) produces a protease and a carbohydrolase both of which have the ability to lyse Rhizopus cell walls. Of the enzymes, the carbohydrolase has been purified to an ultracentrifugally and electrophoretically homogeneous state, and identified as a chitosanase. The enzyme was active on glycol chitosan as well as chitosan. Molecular weight of the purified enzyme was estimated as 31 000 and isoelectric point as pH 8.30. The enzyme was most active at pH 5.6 and at 40 degrees C with either Rhizopus cell wall or glycol chitosan as substrate, and was stable over a range of pH 4.5 to 7.5 at 40 degrees C for 3 h. The activity was lost by sulfhydryl reagents and restored by either reduced glutathione of L-cysteine. An abrupt decrease in viscosity of the reaction mixture suggested an endowise cleavage of chitosan by this enzyme.     

Fermentation of cassava peels for the production of cellulolytic enzymes

Cassava peels were used as a substrate for the production of cellulolytic enzymes. Under solid substrate fermentation conditions and a Rhizopus sp., thermostable cellulolytic enzymes were produced. Optimal production temperature and pH were 45°C and 5.6 respectively. Kinetic studies of the enzymes showed that the cellulase C₁ activity was optimal at pH 5.0 and 50°C, whereas that of cellulase C_x was optimal at pH 7.0 and 60°C. The enzymes degraded ca 44% of sorghum grains in 6 h, thus suggesting a possible use in saccharification processes. The results also showed the possibility of re-cycling cassava peels as a cheap substrate for the enzyme industry. and accepted 6 June 1989     

Interconversion of aflatoxin B1 and aflatoxicol by several fungi.

Four fungal strains, namely, Aspergillus niger, Eurotium herbariorum, a Rhizopus sp., and non-aflatoxin (AF)-producing Aspergillus flavus, which could convert AF-B1 to aflatoxicol (AFL), could also reconvert AFL to AF-B1. The interconversion of AF-B1 to AFL and of AFL to AF-B1 was ascertained to occur during proliferation of the fungi. These reactions were distinctly observed in cell-free systems obtained from disrupted mycelia of A. flavus and the Rhizopus sp., but they were not observed in culture filtrates from intact (nondisrupted) mycelia of the same strains. The interconversion activities of AF-B1 and AFL were not observed when the cell-free systems were preheated at 100 degrees C. These findings strongly suggest that the interconversion of AF-B1 and AFL is mediated by intracellular enzymes of A. flavus and the Rhizopus sp. In addition, the isomerization of AFL-A to AFL-B observed in culture medium was also found to occur by the lowering of the culture pH.     

Interconversion of aflatoxin B1 and aflatoxicol by several fungi

Four fungal strains, namely, Aspergillus niger, Eurotium herbariorum, a Rhizopus sp., and non-aflatoxin (AF)-producing Aspergillus flavus, which could convert AF-B1 to aflatoxicol (AFL), could also reconvert AFL to AF-B1. The interconversion of AF-B1 to AFL and of AFL to AF-B1 was ascertained to occur during proliferation of the fungi. These reactions were distinctly observed in cell-free systems obtained from disrupted mycelia of A. flavus and the Rhizopus sp., but they were not observed in culture filtrates from intact (nondisrupted) mycelia of the same strains. The interconversion activities of AF-B1 and AFL were not observed when the cell-free systems were preheated at 100 degrees C. These findings strongly suggest that the interconversion of AF-B1 and AFL is mediated by intracellular enzymes of A. flavus and the Rhizopus sp. In addition, the isomerization of AFL-A to AFL-B observed in culture medium was also found to occur by the lowering of the culture pH.     

Purification and characterization of protease from a newly isolated Rhizopus oryzae

A newly isolated Rhizopus oryzae was found to exhibit some unusual phenomenon of secreting alkaline protease which was purified and characterized. The molecular weight was determined to be 28,600 dalton in gel electrophoresis. The enzyme is stable in the pH range from 3 to 11 and most active at pH 8. The temperature optimum of this thermostable biocatalyst is at 60 °C. The enzyme is sensitive to metal chelators, most of the metal ions (excepting a few monovalent cations) and inhibitor like PMSF. This indicates that the protease of isolated Rhizopus oryzae falls under alkaline serine group.     

Ferric reductase, superoxide dismutase and alkaline phosphatase activities in siderophore producing fungi

Enzymes associated with release of iron from internalized ferrated siderophore (ferrisiderophore reductase), with damage to the cell at high iron concentration (superoxide dismutase) and siderophore synthesis (alkaline phosphatase), were examined in 3 test fungi viz., Aspergillus sp. ABp4, Aureobasidium pullulans and Rhizopus sp. Extracellular ferrisiderophore reductase activity was present in all the three fungi, but Aureobasidium pullulans, that showed the highest activity (84.3 microM min(-1)), was the only one to produce intra-cellular ferric reductase (147.9 microM min(-1)). Superoxide dismutase was produced by Aureobasidium pullulans and Rhizopus sp., but not by Aspergillus sp. ABp4, that showed intra-cellular enzyme activity in case of ferric reductase and alkaline phosphatase. Maximum SOD activity was seen in Aureobasidium pullulans both extra-cellularly (93.83 ng ml(-1)) and intra-cellularly (57.14 ng ml(-1)). All the test fungi examined, produced intra-cellular alkaline phosphatase. There was no extracellular alkaline phosphatase. Among the three fungi, Aureobasidium pullulans showed highest alkaline phosphatase activity (129.9 microM min(-1)) and Aspergillus sp. ABp4 the least (76.4 microM min(-1)).     

A comparison of raw starch-digesting glucoamylase production in liquid and solid cultures of Rhizopus strains

Maximum growth for Rhizopus sp. A-11 was obtained at a zinc ion concentration of 0.7 ppm in a liquid medium. Glucoamylase (GA, EC 3.2.1.3) production in Rhizopus sp. A-11 was maximized at 710 U/ml, at the presence of 75 ppm for calcium and 0.7 ppm of zinc ions in liquid medium. Zinc ion is known as an essential biometal for Rhizopus growth; however, growth was inhibited by the zinc ion concentration, not maximized. Although calcium ion was not necessary to Rhizopus growth, GA production using Rhizopus sp. A-11 was markedly stimulated by calcium ion concentration over 75 ppm in the liquid medium. The GA productivity of the present liquid culture was about 4.4 times higher than that of the solid state culture, based on the unit starch amount in the liquid and solid media carbon source. The characteristics of the GA produced by the Rhizopus sp. A-11 liquid culture were interesting; that is, almost all the GA produced was classified as raw starch-digesting GA (GA-I). Secreted protein in the culture liquid after 30 h was nearly GA, and had a limited amount of impure protein. As a result, it was found that using a Rhizopus culture in a specified metal-ion regulated medium was an effective method for producing GA. Thus the present culture method was renamed the "metal-ion-regulated liquid culture method".     

根霉α-半乳糖苷酶的三相分离及其酶学性质

根霉Rhizopus sp. A01发酵豆渣产α-半乳糖苷酶,粗酶液依次经过三相分离、Sephadex G-100凝胶过滤获得了电泳纯的α-半乳糖苷酶,纯化了6.7倍,总酶活回收率达到46%;凝胶过滤和SDS-PAGE显示该酶为相对分子质量为87.6kDa的单体蛋白。该酶水解对硝基苯-α-D-吡喃半乳糖苷的最适pH值为5.0,最适温度为55℃,表观Km、kcat/Km分别为2.56mmol/L、47,400L/mol·s;能微弱水解蜜二糖和棉子糖,水解蜜二糖的速率是水解棉子糖速率的3.4倍;水解活性受多种     

Determination and kinetics of producing glucosamine using fungi

This work used three fungi, Rhizopus oligosorus BCRC 31996, Monascus pilosus BCRC31527, and Aspergillus sp. BCRC31742, to produce glucosamine by using submerged fermentation and flask cultures. The reaction of glucosamine with 1-naphthyl isothiocyanate as derivatizing agent was carried out in pyridine at 50 degrees C for 1 h. The derivative was accurately analyzed and quantified by using high performance liquid chromatography. The relative standard deviation of glucosamine determined between experimental and real values were less than 2%. The kinetic and strategy of producing glucosamine in a flask culture was investigated to achieve an optimum yield of glucosamine under different conditions including three kinds of fungi, medium, and pH values. The descending ability of producing glucosamine for the three fungi was Aspergillus sp. BCRC31742 > Monascus pilosus BCRC31527 > Rhizopus oligosorus BCRC 31996 under the conditions studied. The experimental result shows that the glucosamine concentration had an optimum value and was 3430 mg/L by using Aspergillus sp. BCRC31742 culture in glucose and peptone (GP) medium, the yield of which was the best amount using wild-type microorganisms in the past. The generation culture of fungi and the pH control played important roles in enhancing the yield of glucosamine. The specific growth rate of the microorganism and the biomass, content, yield, and productivity of glucosamine were calculated as well.     

Inhibition of beta-fructofuranosidases and alpha-glucosidases by synthetic thio-fructofuranoside

A synthetic beta-thio-fructofuranoside of mercaptoethanol inhibited not only beta-fructofuranosidases but also alpha-glucosidases. The compound was hardly hydrolyzed by the glycosidases. The thio-fructoside competitively inhibited beta-fructofuranosidases from Aspergillus niger, Candida sp., and Saccharomyces cerevisiae, but not Arthrobacter beta-fructofuranosidase at all. Sucrase activity of rat intestinal sucrase/isomaltase complex was also suppressed in the presence of the thio-fructoside. The thio-fructoside showed noncompetitive inhibition toward maltase activity of the rat intestinal enzyme complex and Saccharomyces sp. alpha-glucosidase. Inhibition against the Bacillus stearothermophilus alpha-glucosidase, Rhizopus glucoamylase, and porcine kidney trehalase were more slight than that against these two alpha-glucosidases.