一株产胆固醇氧化酶的不动杆菌的筛选鉴定及特性研究

目的：筛选鉴定产胆固醇氧化酶的菌株并对其酶的性质及发酵条件进行初步的研究。方法：利用唯一碳源的胆固醇平板筛选,酶活测定比较得酶活力最高的菌株;生理生化试验结合16S rDNA序列分析鉴定其种属,单因素及正交实验优化培养基及发酵条件。结果：所得菌株H4与产不动杆菌（Acinetobacter）有最近的亲缘关系,其胆固醇氧化酶作用的最适温度和pH分别为37℃和8.0,金属离子Mg2＋、Zn2＋、Fe2＋对该酶具有一定激活作用,菌株产酶的最适培养基为（g/L）：胆固醇1.5,蔗糖5,蛋白胨7,硝酸铵3,吐温1.0,pH7.5;最适培养条件为33℃,15mL培养基/100mL三角瓶,摇床培养（200r/min）48h,优化后发酵液酶活达135.8U/L。结论：获得了1株产胆固醇氧化酶的菌株H4,并初步鉴定为不动杆菌（Acinetobacter）。     

嗜热菌Anoxybacillu sp.产淀粉酶培养基优化及产酶条件研究

目的：对产淀粉酶嗜热菌Anoxybacillu sp.菌株进行培养基优化及产酶条件研究,以便提高菌株的产酶能力,并为下一步菌 株的诱变育种研究提供基础。方法：常规方法液体培养菌株,用平板初筛和DNS法复筛选择产淀粉酶能力较高的菌株;单因素筛 选培养基最适的碳源、氮源、Ca2+浓度和Mg2+浓度,对单因素筛选的最佳碳源、氮源、Ca2+和Mg2+的三个较佳浓度进行四因素三 水平正交试验优化培养基;对培养基不同pH值及不同培养温度进行培养条件研究。结果：产淀粉酶菌株筛选结果显示：六株菌中 淀粉酶酶活力值最大的是菌株Anoxybacillu sp.DL4,差异有统计学意义（P＜0.05）。培养基单因素筛选结果显示：最适碳源为麦芽糖、最适氮源为 硝酸铵、最适Ca2+、Mg2+浓度均为0.02%,差异有统计学意义（P＜0.05）。培养基优化结果显示：C 源0.1 %,N源0.2 %,Mg2+ 0.04%, Ca2+ 0.04 %为最佳的培养基成分组合。产酶条件筛选结果显示：培养基pH 值为6、培养温度为55 ℃时菌株产酶水平最高,差异有 统计学意义（P＜0.05）。结论：培养基的优化及最适的产酶条件能提高嗜热菌Anoxybacillu sp.DL4 产淀粉酶能力,Ca2+、Mg2+离子 对菌株产淀粉酶有促进作用。     

一株蝉拟青霉产N~6-(2-羟乙基)腺苷静置发酵条件的研究

为了提高蝉拟青霉122菌株中N~6‐(2‐羟乙基)腺苷(HEA)的产量。采用静置液体培养方法,以HEA产量为指标,筛选得到122菌株在查氏培养基上的HEA产量优于沙氏和PD培养基;以查氏培养基为基础培养基,在26℃培养40d时,HEA产量达到最大;在黑暗条件培养优于光照条件培养;最优碳源是蔗糖和葡萄糖;最优氮源是磷酸氢二铵;最优无机盐是KH_2PO_4;最优前体物为次黄嘌呤;最适氨基酸为L‐谷氨酸。正交实验结果表明蔗糖是影响122菌株产HEA的最主要的因子,在筛选出的优化培养基上得到122菌株HEA的最大产量为(130.22±0.60)mg/L,较优化前HEA的产量提高9.73倍。     

链霉菌产木聚糖酶条件和酶学性质以及重离子诱变对产酶的影响研究

以一株由青藏高原牦牛粪中分离出的链霉菌为出发菌株,对其培养特性、产酶条件和酶学性质进行初步研究.通过重离子诱变,筛选出遗传稳定的高产菌株.结果表明,该菌以玉米芯和麸皮(1∶1)为碳源能高效地诱导木聚糖酶的胞外分泌,其最适培养基和培养条件氮源为酵母膏、初始pH7、培养温度为25℃,在此条件下,第4天酶活力达到峰值3480.25 U/mL.说明该酶能够利用农业废弃物高效生产木聚糖酶.该菌株所产木聚糖酶的最适反应温度为15℃、pH4,属低温酸性木聚糖酶.经重离子诱变后,筛选出一株高产菌株SZ10-7,其酶活力可达5 338.42 U/mL.     

嗜热菌Anoxybacillus sp.产淀粉酶培养基优化及产酶条件研究

目的:对产淀粉酶嗜热菌Anoxybacillus sp.菌株进行培养基优化及产酶条件研究,以便提高菌株的产酶能力,并为下一步菌株的诱变育种研究提供基础。方法:常规方法液体培养菌株,用平板初筛和DNS法复筛选择产淀粉酶能力较高的菌株;单因素筛选培养基最适的碳源、氮源、Ca~(2+)浓度和Mg~(2+)浓度,对单因素筛选的最佳碳源、氮源、Ca~(2+)和Mg~(2+)的三个较佳浓度进行四因素三水平正交试验优化培养基;对培养基不同p H值及不同培养温度进行培养条件研究。结果:产淀粉酶菌株筛选结果显示:六株菌中淀粉酶酶活力值最大的是菌株DL4,差异有统计学意义(P0.05)。培养基单因素筛选结果显示:最适碳源为麦芽糖、最适氮源为硝酸铵、最适Ca~(2+)、Mg~(2+)浓度均为0.02%,差异有统计学意义(P0.05)。培养基优化结果显示:C源0.1%,N源0.2%,Mg~(2+)0.04%,Ca~(2+)0.04%为最佳的培养基成分组合。产酶条件筛选结果显示:培养基p H值为6、培养温度为55℃时菌株产酶水平最高,差异有统计学意义(P0.05)。结论:培养基的优化及最适的产酶条件能提高嗜热菌Anoxybacillus sp.DL4产淀粉酶能力,Ca~(2+)、Mg~(2+)离子对菌株产淀粉酶有促进作用。     

氧化亚铁硫杆菌的分离及其培养条件优化

目的:获得可应用于烟气脱硫的菌株,并对其培养条件进行优化.方法:从化工厂取土样分离氧化亚铁硫杆菌,分析分离菌株的形态学特征、培养特征及16S rDNA序列,确定菌株的分类地位.通过单因子实验,对培养基中主要成分硫酸亚铁和硫酸铵的浓度进行优化.利用SAS软件中的Box-Behnken法设计实验,通过响应面分析对初始pH、温度、接种量、装液量4个因素进行优化.结果:获得菌株N16,经鉴定为嗜酸性氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans).确定FeSO_4·7H_2O和(NH_4)_2SO_4的最适添加量分别为60/L和1g/L.确定菌株最适培养条件为:初始pH 1.8,温度28℃,转速150r/min,接种量15%,装液量30mL.在最适培养墓及培养条件下,菌株N16的亚铁氧化率可达99.78%.结论:分离得到的菌株适合于微生物法烟气脱硫的应用.     

产壳聚糖酶菌株的分离、鉴定及发酵条件优化

从废弃食用菌培养基周围土壤中分离得到一株产壳聚糖酶的菌株,结合形态学特征与26SrDNA序列进行了分类学鉴定,结果表明,该菌株与高山被孢霉(Mortierella alpina)的同源性较高,达99%,初步鉴定为被孢霉属的一种,命名为KB-1001。并对该菌株的产酶特性进行了研究,结果表明,该菌株液体发酵培养产酶高峰出现在第84h,最适碳源为1%的水溶性壳聚糖,最适氮源为1.87%的(NH4)2SO4,摇瓶培养的最适初始pH值为6.0,最适温度为28℃～30℃,接种量为4%,最佳装瓶量为70 mL/250 mL,150 r/min摇瓶培养,经优化培养后,该菌株发酵液中壳聚糖酶活力最高达到8.130 U/mL。比原始的未经发酵条件优化的产酶活性提高了12.78%。     

高温蛋白酶产生菌的筛选及其产酶条件和酶学性质分析

从徂徕山温泉附近土样中分离到9株产高温蛋白酶菌株,选取一株碱性蛋白酶高产菌株L7为出发菌株,进行显微形态、16S rRNA基因序列分析,将其初步鉴定为短芽孢杆菌(Brevibacillus sp.)。研究该菌株发酵条件,确定产酶的最佳培养基组成为葡萄糖40 g/L,蛋白胨20 g/L,磷酸氢二钠1.4 g/L,氯化钙0.6 g/L,硫酸镁0.4 g/L,通过培养基优化,酶活达到103.08 U/mL。最佳培养条件为250 mL三角烧瓶中装液量50 mL、pH8.0、培养温度为55℃、培养时间为24 h。对该菌株酶学性质研究,L7菌株所产高温蛋白酶的最适温度为55℃,最适pH为10,并且具有良好的温度稳定性和pH稳定性,酶活性受PMSF强烈抑制。     

β-葡聚糖酶高产菌株BS9418F的选育及其发酵条件的研究

经60 Coγ射线辐照处理获得的诱变菌株芽孢杆菌BS9418F ,其产酶活力比出发菌株提高 30 %以上。该菌株以大麦粉 7%、玉米粉 3%、豆粕 3%及适量无机盐为培养基最佳配比 ,其最适培养条件为 :培养基初始 pH 7.0 ,摇瓶装量 5 0mL/ 30 0mL三角瓶 ,种龄 16～ 2 0h ,接种量 2 %～ 3% ,培养温度 36～ 37℃ ,发酵周期 40h。在优化条件下 ,摇瓶发酵产 β 葡聚糖酶活力高达 5 5 0 0u/mL以上 ,比出发菌株初始发酵水平提高了 4倍以上     

葡萄糖氧化酶产生菌的诱变育种及发酵工艺优化

文章为优化葡萄糖氧化酶产生菌的诱变育种和发酵工艺，将桔青霉CICC 40277作为生产菌株，通过对固、液培养基中菌种的生长和产酶活力进行比较，选取木薯叶为培养基质，经固体培养活化后，菌株的产酶活力最高达到66.48 U/g。然后采用2-脱氧-D-葡萄糖为菌株抑制剂，以甲基红为指示剂设计了一种高效、简便的筛选方法。通过紫外诱变育种，最终筛选得到一株高产菌株Uv-7，其产酶活力达到79.76 U/g，比原始菌株提高了20%。采用单因素试验对Uv-7菌株产葡萄糖氧化酶的最佳菌种活化条件进行优化，得到最适条件为：培养时间144 h、培养温度30℃、接种量20%(V/V)；最适培养基组分为：以5.5 g木薯叶为固体基质，按照1∶1(W/V)的固液比添加盐溶液(g/L):MgSO₄·7H₂O 0.5、Na₂HPO₄ 2.0、KCl 0.3、CaCO₃ 3.0、葡萄糖30、酵母粉6，当pH为6.0时，菌株经活化后产葡萄糖氧化酶的活性提高到了101.52 U/g，与原始菌株相比提高了52.7%...     

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