均匀设计法对产几丁质酶细菌C4发酵条件的优化

系统研究了碳源,氮源,起始pH值、培养基装量、培养温度和时间等因素对细菌C4产几丁质酶的影响。结果表明,碳、氮源分别以胶体几丁质、KNO和蛋白胨最好;在起始pH值7．6—8．5,培养基装量为三角瓶体积的12％,培养温度28℃,振荡培养(180r／min)5d时最有利于几丁质酶的产生。在此基础上通过均匀设计法优化了发酵培养基配方。优化后的培养基配方为：胶体几丁质1．5％,蛋白胨0．55％,KNO3 0．3％,MgSO4 0．09％,Tween80 0．005％。在该条件下,几丁质酶活力达2．68U／mL,比在原基础培养条件下的酶活力提高90．1％。     

黑曲霉GD-6纤维素酶液体发酵条件的研究

采用黑曲霉 (Aspergillusniger)GD 6液体发酵生产纤维素酶 ,研究了碳源、氮源、培养基起始 pH值、接种量、摇床转速、通气量对该菌株产纤维素酶活力的影响。结果表明 ,GD 6的最适发酵温度为 2 8～ 3 0℃ ,产酶pH为 5 .5～ 6.0 ,摇床最适转速为 1 5 0r/min ,最佳接种量为 1 0 %。在以 6.0 %稻草粉为碳源、1 %豆饼粉为氮源时产酶活力最高。在最适培养条件下 ,发酵周期为 1 2 0h,发酵液中CMC酶活为 1 88.6U/mL ,FP酶活为 2 7.0U/mL。     

培养条件对棘孢曲霉SM—L22所产纤维素酶系组成的影响

本文研究了影响棘孢曲霉SM－L22纤维素酶系组成的培养条件,研究结果表明,碳源,氮源和初始pH对棘孢曲霉所产生纤维素酶的内,外切酶组分的比例有明显的影响,在2％麸皮,1％CF11,0．5％尿素或含尿素的复合氮源为氮源,初始pH为4．5时,28℃培养120h后,内,外切酶的比值最大,内切酶活可达到3．1Iu/ml,FPA为0．105IU／ml,CMCase/FPase的比值为30．6。     

木霉菌株T6木聚糖酶固态发酵条件和酶学性质研究

研究了碳源和氮源、起始pH、接种量及温度等条件对一野生型木霉Trichodermasp.T6菌株固态发酵产木聚糖酶的影响。在28℃培养4d后,酶活力可达1918IU／g干培养物。酶的最适反应温度为50℃,最适反应pH4．5。不同温度保温1h后,测定酶的半失活温度为47．7℃,酶的pH稳定性也进行了研究。     

Aspergillus sp.脂肪酶发酵条件优化及酶学性质的研究

作者为了得到一种热稳定性较好的脂肪酶新酶种,通过研究分离白极端环境的Aspergillus sp．的最佳产酶条件及其所产脂肪酶的酶学性质,得出了该菌产酶的最佳发酵条件为：以1％黄豆饼粉为氮源、0．2％玉米淀粉为碳源,1．5％橄榄油为诱导物,起始pH6．0左右。装量10mL（250mL三角瓶。摇瓶转速180r／min）、发酵时间为96h。在最佳发酵条件下可得最大发酵酶活36U/mL。Aspergillus sp．所产的脂肪酶的酶学性质是：最适pH为9．0,在pH5．0—10．0于20℃下放置24h后,残余酶活仍保持在起始酶活的90％以上;该酶的最适温度为50℃,50℃保温60min后仍保留70％以上的酶活。Aspergillus sp．所产脂肪酶的热稳定性较好。     

金龟子绿僵菌固态发酵产壳聚糖酶

对金龟子绿僵菌（Metarhizium anisopliae）AS3．4606产壳聚糖酶进行了固态发酵条件优化及酶学部分特征的研究。正交实验结果表明,以麸皮为碳源,日本根霉菌丝体粉末为氮源,在起始pH5．0,m（碳）：m（氨）为1：4,m（干重）：m（液体）为1：1．4,27℃下培养120h,壳聚糖酶活性可达35．08U／g（干培养基）。粗酶液的最适反应温度为40℃,最适反应pH为5．0,酶在pH5．0～6．0条件下稳定性最高。该酶不能水解固体甲壳素和纤维素粉末,最适底物为胶体壳聚糖。     

枯草芽孢杆菌中性β-甘露聚糖酶的产生及性质

由土壤中分离出一株产中性β甘露聚糖酶的枯草芽孢杆菌(Bacillus subtilis),编号BM9602。该菌在液体培养条件下,产生中性β甘露聚糖酶。多糖能作为碳源,而单糖不能作为碳源;有机氮源优于无机氮源。产酶最适培养基组成：魔芋粉4%,牛肉蛋白胨和酵母膏各1%。产酶最适培养条件：培养基起始pH85,35℃,振荡培养36〖KG*3]h。以槐豆胶为底物,培养滤液中性β甘露聚糖酶活力为96IU/mL。酶在pH50～100和50℃下稳定;作用最适条件为pH60和50℃;水解魔芋粉和槐豆胶均产生寡聚糖。     

樟绒枝霉(Malbranchea cinnamomea)固体发酵产木聚糖酶的发酵条件优化

[目的] 研究樟绒枝霉(Malbranchea cinnamomea) CAU521利用农业废弃物固体发酵产木聚糖酶的发酵条件.[方法]采用单因素试验法优化影响菌株产酶的各个条件,包括碳源种类、氮源种类、初始pH、初始水分含量、培养温度及发酵时间共6个因素.[结果]获得的最佳产酶条件为:稻草为发酵碳源、2％(W/W)的酵母提取物为氮源、初始pH 7.0、初始水分含量80％和发酵温度45℃.在此条件下发酵6d后木聚糖酶的酶活力达到13 120 U/g干基碳源.[结论]樟绒枝霉固体发酵产木聚糖酶的产酶水平高,生产成本低,具有潜在的工业化应用前景.     

高酶活菌株的筛选及漆酶特性

通过Bavendamn氏反应和液体发酵实验筛选出漆酶高产菌株 ,并对其产酶条件和酶活性进行了研究。结果表明 71株实验真菌中有 64株Bavendamn氏反应呈阳性 ,且阳性菌株都具有漆酶活性 ;不同菌株产酶培养基最适碳源、氮源不同 ,采绒革盖菌以淀粉为碳源、干酪素为氮源 ,毛栓菌以麦草粉为碳源、硫酸铵为氮源 ,有利于酶的分泌 ;不同来源漆酶性质不尽相同 ,采绒革盖菌漆酶最适酶解温度为 2 5℃ ,最适酶解pH值为4.6,毛栓菌则分别为 3 0℃和 pH 4.0 ;K+ ,Zn2 + 等对 2种漆酶均有激活作用 ,Ag+ 则能明显抑制漆酶活性。     

微生物酶拆分方法生产D-泛酸的手性中间体D-泛解酸内酯

筛选到一株产D－泛解酸内酯水解酶的串珠镰孢霉菌（Fusarium moniliforme SW-902)。产酶条件研究表明,用甘油作碳源,蛋白胨作氮源,初始pH8.0,温度26℃,摇瓶培养3d,产酶量最高。在60L和1000L发酵罐中通风发酵45－47h,产酶量为6－8g干菌体／L,D－泛解酸内酯水解酶酶活力达到0．87－0．92IU／g干菌体。该酶的最适反应温度为55℃,最适反应pH为7．0－7．5。在酶不对称水解泛解酸内酯过程中,对溶液加酶量5％－10％,底物浓度10％－20％,控制水解率20％－30％,水解效果最好。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细     

Comparative morphology of the carpel in the Liliaceae: Hewardieae, Petrosavieae, and Tricyrteae

The young pistils in the melanthioid tribes, Hewardieae, Petrosavieae and Tricyrteae, are uniformly tricarpellate and syncarpous. They lack raphide idioblasts. All are multiovulate, with bitegmic ovules. The Petrosavieae are marked by the presence of septal glands and incomplete syncarpy. Tepals and stamens adhere to the ovary in the Hewardieae and the Petrosavieae but not in the Tricyrteae. Two vascular bundles occur in the stamens of the Hewartlieae and Tricyrtis latifolia. Ventral bundles in the upper part of the ovary of the Hewardieae are continuous with compound septal bundles and placental bundles in the lower part. Putative ventral bundles occur in the alternate position in the Tricyrteae and putative placental bundles in the opposite. position in the Petrosavieae. The dichtomously branched stigma in each carpel of the Tricyrteae is supplied by a bifurcated dorsal bundle.