响应面法优化L.lactis WH11-1生成GABA的发酵条件

通过响应面分析的方法对L．1actis Willl-l发酵生产y-氨基丁酸的培养条件进行了优化。运用中心组合设计和响应面分析考察了接种量、初始pH值和培养温度对y-氨基丁酸产量的影响,得出最佳培养条件：接种量4．5％,初始pH值为6．0,培养温度为32℃。在此条件下培养96h,GABA生成量达8．63g／L,实验值与预测值基本相符。     

菊糖酶发酵生产条件的研究

脆壁克鲁维氏酵母（Kluyveromycesfragilis）在pH5．5的适当培养基中,28℃摇瓶培养30h后,进行分批发酵。结果表明：发酵初始pH为6．0～6．5,菊糖浓度为2％,接种量4％,控制前期发酵温度为28℃,33h后发酵温度为32～34℃。发酵周期为70h左右,最高产酶达240u／ml。在5L自控发酵罐中,产酶达到同样水平,发酵周期缩短约10h。     

魔芋葡甘聚糖酶实验性生产条件初探

在5L发酵罐上用正交试验检测不同温度、pH和接种量对魔芋葡甘聚糖酶发酵生产的影响。试验表明,产酶的最佳条件为温度50℃,pH5.5～6.0,接种量10%,发酵前期搅拌速度100r·min-1,通气量20L·h-1,6h后搅拌速度改为50r·min-1,通气量10L·h-1,在此条件下获得的酶比活力为4.812×106U·g-1,总活力达到7.810×106U·L-1。培养8h后细菌生物量、产物含量迅速提高,24h达到顶峰时期。发酵动力学属于偶联型。     

L-苹果酸产生菌F-871变株合成延胡索酸酶的研究

温特曲霉Aspergillus wentii F-871是高效转化延胡索酸为L-苹果酸的变株,通过对其合成延胡索酸酶的因素进行研究,筛选了培养基主要营养元素有L-精氨酸、酪氨酸、丝氨酸、天冬氨酸、苏氨酸、赖氨酸及相应含量丰富的酵母粉、黄豆饼粉和玉米浆。该变株生长阶段条件为：pH6．0,温度2830℃,培养时间为24h,酶合成阶段最适条件：接种量15％,初始pH6．8,培养温度2830℃,装量8090ml／500ml,酶合成周期40h。在优化的培养条件下,F-871变株延胡索酸酶合成水平可达156．33u／g,100ml发酵液中的酶可将延胡索酸转化为L-苹果酸32．06g,比国内一步发酵法产酸88．5％提高约4倍,转化率由85％提高到106．87％,发酵周期由90h缩短至57h。     

黑木耳深层发酵工艺条件的研究

研究了碳源、氮源、接种量、初始pH、温度等对深层发酵黑术耳的生物量和多糖产量的影响,结果表明葡萄糖、酵母膏、豆饼粉有利于黑木耳菌体生长和胞外多糖的形成。在初始pH5．3、接种量10％、种龄6d,温度28℃、250ml摇瓶装液量80ml的条件下,黑木耳深层发酵结果最佳,在此基础上进行摇瓶发酵曲线测定。确定了黑木耳适宜发酵周期为96h,胞外多糖最高可达5.01g/L。     

鸡腿菇液体深层发酵工艺条件的研究

目的：研究碳源、氮源、接种量、初始pH值、温度等对鸡腿菇深层发酵的生物量和多糖产量的影响。方法：通过摇瓶培养确定了该菌株的发酵优化条件,在此条件下,获得了较高的多糖产量。结论：结果表明葡萄糖、酵母浸粉有利于鸡腿菇菌体生长和胞外多糖的形成,在初始pH值6、接种量10％、温度26℃、250ml摇瓶装液量l00ml的条件下,鸡腿菇深层发酵结果最佳,在此基础上进行摇瓶发酵曲线测定,确定了鸡腿菇适宜发酵周期为144h,胞外多糖最高可达1．98g/L。     

离子注入选育高产L-乳酸的米根霉突变株及其发酵特性研究

通过氮离子注入获得米根霉突变株RQ4012,其利用木糖的能力比出发菌株提高了1.6倍;通过多次传代,证明其具有良好的遗传稳定性。试验测定菌株RQ4012发酵木糖生产L-乳酸的最佳发酵条件:木糖10%,生理盐水浸泡孢子9 h,(NH4)2SO43 g/L,接种量4%,CaCO3添加量6%,装液量20%,温度37℃,转速200 r/min,在此条件下,乳酸产量达到79.51 g/L。对混合糖的发酵进行了探索,结果表明该菌能高效利用混合糖生产L-乳酸,在利用植物纤维素水解液生产L-乳酸上有良好的应用前景。     

L-精氨酸高产菌红曲霉的筛选及发酵初步研究

对不同样品中的真菌进行了L-精氨酸高产菌株的筛选,从红曲米中分离出1株高产L-精氨酸菌株红曲霉H13,其初始发酵液中L-精氨酸产量为1.67 g/L.通过单因素实验对其液体发酵进行研究.结果表明,最佳碳源是可溶性淀粉,最佳浓度为10％,最佳氮源是蛋白胨,最佳浓度为3％,最佳pH值4.5,温度30℃,种子培养时间为18 h,摇瓶装液量50 mL/250 mL.转速为120 r/min,发酵时间7d.在此条件下进行发酵培养,所得发酵液产L-精氨酸4.08 g/L,菌丝体干重为10.32 g/L,菌丝体中L-精氨酸含量为24.17 mg/g.     

XCCNAU—92发酵生产黄原胶的适宜条件

XCCNA－92发酵生产黄原胶的适宜条件是：好氧,发酵温度为30℃,培养基起始pH为7.0,接种量6％,发酵周期60h。利用最佳培养基配方,在30℃,150r／min条件下发酵72h,工业级黄原胶产量达40.84g／L,发酵液粘度86000cp,丙酮含量4．1％,碳源转化率达68.1％。     

GABAA受体蛋白片段在大肠杆菌细胞表达条件研究*

为了提高GABAA受体a1蛋白片段在大肠杆菌中表达量,研究了重组菌的发酵条件,包括培养基、接种量、温度、摇床转速、pH、诱导培养时间和诱导剂IPTG使用浓度等对GABAA受体蛋白片段表达的影响。结果表明重组菌以LB培养基为发酵基质,按3％接种量,37℃培养细胞3.5h后IPTG 32℃诱导5h,菌体生物量为3.25g/L,目标蛋白表达量达95mg/L。用16L发酵罐进行放大培养,菌体生物量达4.95g/L,发酵周期5.5h,最高目标蛋白表达量达到136mg/L.     

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.     

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     

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.     

Entwicklungsgeschichte und Ultrastruktur von Pollenkitt und Exine bei nahe verwandten entomophilen und anemophilen Angiospermensippen derAlismataceae,Liliaceae, Juncaceae,Cyperaceae, Poaceae undAraceae

Some closely related members of the monocotyledonous familiesAlismataceae, Liliaceae, Juncaceae, Cyperaceae, Poaceae andAraceae with variable modes of pollination (insect- and wind-pollination) were studied in relation to the ultrastructure of pollenkitt and exine (amount, consistency and distribution of pollenkitt on the surface of pollen grains). The character syndromes of pollen cementing in entomophilous, anemophilous and intermediate (ambophilous or amphiphilous) monocotyledons are the same in principal as in dicotyledons. Comparing present with former results one can summarize: 1) The pollenkitt is always produced in the same manner by the anther tapetum in all angiosperm sub-classes. 2) The variable stickiness of entomophilous and anemophilous pollen always depends on the particular distribution and consistency of the pollenkitt, but not its amount on the pollen surface. 3) The mostly dry and powdery pollen of anemophilous plants always contains a variable amount of inactive pollenkitt in its exine cavities. 4) A step-by step change of the pollen cementing syndrome can be observed from entomophily towards anemophily. 5) From the omnipresence of pollenkitt in all wind-pollinated angiosperms studied one can conclude that the ancestors of anemophilous angiosperms probably have been zoophilous (i.e. entomophilous) throughout.

     

Identification and Characterization of the First Equine Parainfluenza Virus 5

正Dear Editor,Parainfluenza virus 5 (PIV5), known as canine parainfluenza virus in the veterinary field, is a negative-sense,nonsegmented, single-stranded RNA virus belonging to the Paramyxoviridae family (Chen 2018). The virus was first reported in primary monkey kidney cells in 1954 (Hsiung1972), then it has been frequently discovered in various