酿酒酵母培养基中主要因素对海藻糖积累的影响

在对实验室保藏菌种Saccharomyces cerevisiae HY01优化前的摇瓶发酵观察的基础上,采用单因子与响应曲面相结合的实验设计方法研究了酿酒酵母培养基中的初始葡萄糖浓度、无机氮源硫酸铵浓度、酵母浸出粉浓度、碳源与无饥氮源的交互作用以及无机盐和微量元素浓度对海藻糖积累的影响。实验证明碳氮源交互作用明显,并得到了以上各因素的最优值,即初始葡萄糖浓度为20g／L,(NH4)2SO4浓度为4．5g／L,酵母浸出粉浓度为5g／L,微量元素溶液5．0ml／L;硫酸镁0．3g／L;磷酸氢二钠3．67g／L;磷酸二氢钾0．76g／L时,酿酒酵母中海藻糖的干重含量可以达到14．74％,比优化前海藻糖的干重含量12．24％提高了20．41％．     

高浓度糖发酵制备乙醇

以树干毕赤酵母为发酵菌株,混合糖（木糖、葡萄糖）为发酵底物,通过培养基和培养条件的改变来确定树干毕赤酵母高糖浓度发酵时所需的条件。研究结果表明：在24h发酵周期内初始木糖质量浓度为63．0g／L较适宜;在36h发酵周期内初始木糖质量浓度为72．0g/L较适宜。24h发酵周期内,在36．0g／L木糖中添加的葡萄糖质量浓度以54．0g/L为最佳,发酵结束乙醇质量浓度达32．9g／L;36h发酵周期内,添加的葡萄糖质量浓度以72．0g／L为最佳,发酵结束乙醇质量浓度为36．9g／L。以（NH4）2SO4为N源时较适合戊糖发酵制备乙醇,（NH2）2SO4的最佳质量浓度为1．1g／L。发酵前8h摇床转速为90r／min,后16h为150r／min,乙醇质量浓度较高,可达17．5g/L。     

海藻糖生产过程中产酶发酵条件的研究

研究了产酶的培养基组分和比例以及最佳培养条件对微球菌生产麦芽寡糖基海藻糖合成酶(MTSase)和麦芽寡糖基海藻糖海藻糖水解酶(MTHase)的影响,得到最优培养基组成为：葡萄糖2．0％,酵母膏2．0％,蛋白胨1．0％,磷酸氢二钾0．1％,硫酸镁0．05％;优化后的培养条件为：以15％的接种量接种至250mL的锥形瓶中,装液量为50mL,初始pH值7．5～8．5,培养温度为30℃,摇床培养4d。经优化后菌体干重由原来的1．938g／L增加到18．5g／L,生物量几乎增长了10倍;而酶活也由原来的30．64U／g增加到206．11U／g,酶活提高了接近7倍。     

重组大肠杆菌利用木糖发酵产高纯度L-乳酸

对重组大肠杆菌JH16利用木糖产高纯度的三一乳酸进行研究。通过无氧管驯化EscherwhiacdiJH12菌株得到E．coliJH16,驯化后的菌株茵体浓度提高了31％,乙酸积累减少了43％;在摇瓶中考察不同Mg2＋浓度对EcoliJHl6产三一乳酸的影响,确定最适Mg2＋质量浓度为0．25g/L;EcoEJH16以60g/L木糖为C源,在7L全自动发酵罐中添加0．25g／LMg2＋,乳酸积累量提高了18％,达38．18g/L,乳酸纯度高达95％;E．coliJH16在30g／L木糖和30g／L葡萄糖混合C源中,优先利用葡萄糖,当葡萄糖质量浓度低于1．56g/L后,菌体开始利用木糖进行乳酸发酵,最终得到39g／L乳酸。     

响应面法优化毛霉菌发酵培养基

采用响应面分析方法优化毛霉菌B的发酵培养基,首先通过单因素试验筛选出葡萄糖为最适碳源,酵母膏和玉米浆为最适氮源,用Plackett—Burman试验对葡萄糖、酵母膏、玉米浆、MgSO4、FeSO4、NILCl/、HPO4进行评估并筛选出具有显著效应的3个因素：葡萄糖、酵母膏、玉米浆,再通过最陡爬坡试验逼近其最大响应区域,最后采用Box—Behnken试验对其用量进行优化,得到毛霉菌最佳发酵培养基（g/L）：葡萄糖51．54,酵母膏5．22,玉米浆14．31,MgSO40．5,FeSO40．1,NH4Cl3,k2HPO43,pH6．0～6．5。培养基优化后,毛霉生物量由23．51g／L提高至31．13g/L,比对照组提高32．41％,腺嘌呤转化率由53．59％提高至59．97％,ATP产率由6．56g／L提高至7．34g／L,比对照组提高11．89％。     

利用Design-Expert软件优化丝氨酸羟甲基转移酶产酶培养基

利用Design-Expert软件中水平设计和响应面分析法对产酶基本培养基主要成分进行了优化,经过逐步回归分析建立了丝氨酸羟叫基转移酶（SHMT）活力对培养基主要成分的二次回归模型,其回归方程的决定系数达到了0．9984。得到的最佳培养琏主要组成为：葡萄糖29．5g／L、硫酸铵18．1g/L、玉米浆3．79g／L。SHMT活力最高达到113．7U／ml,比优化前（77U／mL）提高了47．7%。优化后的酶液经酶促反应50h,能催化产生10g／L的L-丝氨酸,比优化前（6g／L）提高66．7％。     

丝状真菌Glarea lozoyensis SIIA-F1108产纽莫康定B0发酵条件的研究

【目的】采用响应面法优化丝状真菌Glarea lozoyensis SIIA-F1108发酵生产纽莫康定B_0培养基,提高发酵产量;通过氮源优化,降低发酵液菌体浓度,改善发酵过程的溶氧水平。【方法】采用Plackett-Burman设计和响应面法进行培养基优化,筛选出对纽莫康定B_0产量具有显著影响的因素;通过最陡爬坡实验及Box-Behnken设计,并利用Design-Expert软件对实验数据进行回归分析,得到优化的发酵培养基配方;通过对优化培养基中氮源组分进行全因子实验,最终得到高产量和低菌体浓度发酵培养基。【结果】实验数据表明:甘露醇、脯氨酸和葡萄糖对纽莫康定B_0产量影响最大;最佳浓度分别为甘露醇167.3 g/L、脯氨酸26.1 g/L、葡萄糖28.5 g/L。采用优化后的培养基进行摇瓶发酵,纽莫康定B_0产量达到了1 840 mg/L,较优化前提高了42%,与预测结果一致。用硫酸铵部分替换棉籽饼粉后,发酵液菌体浓度降低,在100 L发酵罐上对优化后的结果做了进一步的验证,纽莫康定B_0产量达到1 980 mg/L。【结论】模型预测值与实验值有较高吻合度,具备较高可信度和显著性,发酵产量提高了42%,响应面实验设计和分析方法能够有效地用于丝状真菌Glarea lozoyensis SIIA-F1108产纽莫康定B_0发酵培养基进行优化。通过调整培养基中的氮源组成,降低了发酵液菌体浓度,改善了发酵过程的溶氧水平。     

白腐菌产锰过氧化物酶培养基的优化

黄孢原毛平革菌(Phanerochaete Chrysosporium)5．776在初始发酵培养基中产胞外锰过氧化物酶活力极低。为了显著提高锰过氧化物酶活力,对初始发酵培养基进行优化。通过调整培养基中碳源、氮源种类和含量,吐温80添加量,Mn^2 终浓度,静置培养温度、时间,采用分光光度计法测定酶活力,发现黄孢原毛平革菌在限氮高锰培养基中产生较高的锰过氧化物酶。静置液体培养的优化条件是：葡萄糖10g／L;酒石酸铵2mmol／L;吐温80 lg／L;Mn^2 9．9μg／L;于34℃静置培养5d;产MnP活力达1200U／L,比优化前提高了近17倍。     

手性拆分环氧氯丙烷菌株的筛选、鉴定及产酶条件研究

从土壤中筛选到5株环氧化物水解酶生产菌,并通过ITS序列鉴定了其中的C375菌,结果为黑曲霉（Aspergillus nigerZJB-09103）。考察了培养基不同碳源、氮源、金属离子和pH等对产酶的影响,得到了较佳的培养基条件：淀粉16g／L,豆饼粉3g／L,蛋白胨3g／L,KH2PO4 0．4g／L,K2HPO4 0．8g／L,MgSO4 0．2g／L,ZnSO4 0．03g／L,pH6．5。采用优化后的培养基条件,酶活力达到156．1U／L,比优化前初始发酵培养条件下的酶活提高了252％,当环氧化物水解酶催化时间为10h时,（s）-环氧氯丙烷的对映体过量值（e．e．）可达99．0％。产率为18．6％。     

培养基及培养条件对杜仲愈伤组织生长及次生代谢产物含量的影响

以MS、LS、B5、N6、H、Nitsch、White、1／2MS为基本培养基,分别添加0．5mg／L NAA和0．5mg／L BA,分析不同类型培养基对杜仲愈伤组织生长及次生代谢产物含量的影响,并以B5培养基进行光照条件、碳源、蔗糖浓度试验。结果表明：B5培养基不仅有利于愈伤组织生长,也有利于总黄酮的形成,而1／2MS培养基有利于绿原酸的积累;12h／d光照对愈伤组织的生长及绿原酸和总黄酮的合成有明显的促进作用,黑暗不影响愈伤组织的生长,但却抑制绿原酸和总黄酮的形成;3种碳源中,愈伤组织的增长量、绿原酸和总黄酮的含量均以蔗糖为碳源时最高,葡萄糖最低;蔗糖浓度在10～50g／L范围内绿原酸的含量随着糖浓度的升高而升高,40g／L时愈伤组织的增长量和总黄酮的含量最高。     

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     

Pathogenic Characterization and Full Length Genome Sequence of a Reassortant Infectious Bursal Disease Virus Newly Isolated in Pakistan

<正>Dear Editor,Infectious bursal disease (IBD) is one of the most important diseases of the poultry. The IBD virus (IBDV), a nonenveloped virus belonging to the Birnaviridae family with a genome consisting of two segments of double-stranded RNA (segments A and B), targets B lymphocytes of bursa of Fabricious leading to immunosuppression. In Pakistan,poultry farming is the second biggest industry and IBD is the second biggest disease threating the poultry sector.However, there is limited genome information of IBDV