产赤藓糖醇菌种的诱变育种

以耐高渗酵母为出发菌株,采用紫外线诱变处理,得到了一株变异株C1。其摇瓶发酵产赤藓糖醇24．9g／L左右。通过摇瓶发酵试验,研究了菌株C1的遗传稳定性。研究结果表明,经多次传代实验,菌株C1的发酵产糖醇能力没有改变,表明其是稳定的变异株。赤藓糖醇的产量由诱变前的12、594g／L提高到24.943g／L,提高了98.1％。关键词：     

赤藓糖醇产生菌B845的形态、生理特征

分离筛选到了一株商赤藓糖醇能力高的菌种B845,通过对B845的形态,生理生化特性试验,发现该菌耐高渗,能发酵葡萄糖,蔗糖,麦芽糖,细胞为圆形,椭圆形,单边或多边芽殖,有真菌丝,在固体培养基上培养7d后颜色开始变深,由黄色变成褐黑色,参阅真蓝鉴定手册,初步鉴定为圆酵母属菌（Torula sp.)。     

新型甜味剂--赤藓糖醇产生菌的筛选

从土壤、酿造食品、花粉等样品中分离赤藓糖醇产生菌的方法,分离得到约３００株耐高渗酵母,其中有３株菌产赤藓糖醇,２６０８在葡萄糖培养液中可产赤藓糖醇３２ｍｇ／ｍｌ。     

丛梗孢酵母发酵产赤藓糖醇的响应面优化

为了提高丛梗孢酵母发酵产赤藓糖醇的产量,在前期单因素实验结果的基础上,利用Plackett-Burman实验设计对影响其产赤藓糖醇的发酵条件进行评估并筛选出了影响显著的3个因素:葡萄糖、初始pH和温度.采用响应面法进行实验方案设计,利用SAS软件对其结果进行二次回归分析,确定了优化后的发酵条件为:葡萄糖260g/L、酵...     

赤藓糖醇发酵工艺研究

赤藓糖醇的制备方法主要为微生物发酵法。为提高圆酵母(Torulasp.)B84512转化葡萄糖生产赤藓糖醇的发酵产量,采用控制发酵过程中葡萄糖起始浓度(30.0%)、中间流加葡萄糖浆的工艺使总葡萄糖糖浓度达到40%,发酵120h可产赤藓糖醇162.5gL,生产率为1.35gL·h,而不采取中间流加工艺,起始葡萄糖浓度为40.0%,发酵120h可产赤藓糖醇120gL,生产率为1.00gL·h。通过研究发现在赤藓糖醇发酵过程中采取中间流加葡萄糖工艺,能大大提高赤藓糖醇的发酵水平,提高幅度达30-35%,生产率也有相应提高。     

耐高渗产赤藓糖醇酵母的诱变筛选与鉴定

使用含碘乙酸的固体平板培养基对自然界中富含高浓度糖分的含菌样品进行筛选,获得一株产赤藓糖醇的菌株,再运用紫外线、氯化锂和硫酸二乙酯(DES)对出发菌株进行诱变育种,利用纸层析、高碘酸氧化法和高效液相色谱(HPLC)进行定性、定量分析赤藓糖醇,最终获得一株能够高产赤藓糖醇的耐高渗菌株JunA-27.对该菌株的细胞形态进行了扫描电子显微镜(SEM)观察,提取了菌株的DNA并对18S rDNA进行PCR扩增、测序和DNA序列同源性比对,确定该菌株与Yarrowia lipolytica相似性最高,并将其命名为Yarrowia lipolytica WX 506.     

利用木糖-葡萄糖为原料产乙醇酵母的筛选、鉴定及发酵试验

建立筛选利用木糖为碳源产乙醇酵母模型,获得一株适合利用木质纤维素为原料产乙醇的酵母菌株。样品经麦芽汁培养基培养后,以木糖为唯一碳源的筛选培养基初筛,再以重铬酸钾显色法复筛。通过生理生化和26D1/D2区对筛选得到的菌株进行分析和鉴定,该菌初步鉴定为Pichia caribbica。经过筛选得到的菌株Y2-3以木糖（40g/L）为唯一碳源发酵时：生物量为23.5g/L,木糖利用率为94.7 %,乙醇终产量为4.57 g/L;以混合糖（葡萄糖40 g/L,木糖20 g/L）发酵时：生物量为28.6 g/L,木糖利用率为94.2 %,葡萄糖利用率为95.6%,乙醇终产量为20.6 g/L。Pichia caribbica是可以转化木糖及木糖-葡萄糖混合糖为乙醇的酵母菌株,为利用木质纤维素发酵乙醇的进一步研究奠定了基础。     

汉逊德巴利酵母发酵葡萄糖生产D-阿拉伯糖醇

从378株耐高渗酵母中,筛选到1株由葡萄糖发酵高产D-阿拉伯糖醇的酵母。通过生理生化和分子生物学的鉴定,证实该菌株为Debaryomyces hansenii,保藏编号CICIM Y 0504。研究该酵母摇瓶发酵的主要影响因素,确定其摇瓶发酵条件为:葡萄糖200 g/L,酵母膏10 g/L,初始pH值3,装液量20 mL/250 mL,温度30℃。在此条件下发酵120 h,D-阿拉伯糖醇浓度达90.37 g/L,转化率45.18%。在15 L发酵罐对该酵母进行扩大培养,结果表明,初始葡萄糖浓度200 g/L的分批发酵产D-阿拉伯糖醇64.07 g/L,转化率33.94%;葡萄糖浓度控制在30～50 g/L的分批补料发酵产D-阿拉伯糖醇125 g/L,转化率37.5%。研究结果对葡萄糖发酵生产D-阿拉伯糖醇工业化的实现具有重要启示。     

发酵产泡性能降低的解脂耶氏酵母菌株的获得及其评价

微生物发酵过程中泡沫的产生是发酵领域遇到的共性问题。在不影响发酵性能的前提下抑制菌株的产泡,对简化操作以及降低发酵成本具有较为重要的意义。解脂耶氏酵母(Yarrowia lipolytica,之前称为Candida lipolytica)是一种常用的合成生物学底盘,也是合成赤藓糖醇等功能糖醇的生产菌株。但在发酵合成赤藓糖醇的过程中会产生大量的泡沫,需要添加消泡剂以消除泡沫。【目的】本研究旨在开发一种产泡能力显著降低的解脂耶氏酵母新菌株,以减少赤藓糖醇发酵过程中消泡剂的添加。【方法】本研究利用解脂耶氏酵母中非同源靶向重组占支配地位的原理,采用一段外源DNA随机插入基因组的手段,随机突变基因组,改变菌株的发酵产泡性能,使突变株在发酵过程中不产泡或者降低其产泡的能力。【结果】通过筛选,获得一株在发酵过程中产泡性能显著降低的工程菌株,该菌株在保留高效合成赤藓糖醇性能的同时,显著降低了泡沫的产生。【结论】所获得的菌株对工业发酵合成赤藓糖醇具有较为重要的意义,也为控制其他微生物发酵过程中泡沫的生成提供了思路。     

高浓度盐对耐高渗酵母产多元醇的影响

假丝酵母OS－300菌株在含有30％葡萄糖的高浓度基质中能产三种多元醇,甘油,阿拉伯醇和赤藓糖醇,但是在含18％NaCl的高浓度基质中产甘油,。同时,还发现几种原来不产甘油的耐高渗酵母在含有9％NaCl的高浓度培养液中也能形成大量的甘油,该现象表明：产多元醇耐高渗酵母的代谢途径可以在高盐浓度下被明显地改变。     

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.     

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.     

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