产脂肪酶细菌RYXP的诱变选育及突变株产酶条件优化

以"凤丹"牡丹根际土壤中分离筛选到的产脂肪酶菌株Pseudomonas sp. RYXP作为出发菌株,对其进行了紫外线诱变选育,并采用单因素试验和正交试验方法对活性最强正突变株的产脂肪酶基本特性进行了测定。结果表明,出发菌株Pseudomonas sp. RYXP的紫外线诱变最佳条件为:15 W紫外灯30 cm距离照射1 min;将产脂肪酶活性最强的正突变菌株编号为RYXP-3,单因素试验表明RYXP-3产脂肪酶适宜的碳源为玉米淀粉,适宜氮源为豆饼粉,适宜的磷酸二氢钾含量是0.3%,适宜的初始pH值为7;正交试验表明RYXP-3的最佳的产酶培养基成分组成是:玉米淀粉7%,豆饼粉3%,磷酸二氢钾0.3%,初始pH值为8。在优化方案A1B2C2D3产酶条件下,突变株RYXP-3最高的产酶活性达到56.1 U/mL。突变菌株RYXP-3可作为产油牡丹"凤丹"专用促生菌肥开发的备选资源菌株。     

极地适冷菌Pseudoalteromonas sp. QI-1产适冷蛋白酶发酵条件的优化

对极地适冷菌Pseudoalteromonas sp. QI-1产适冷蛋白酶的发酵条件进行优化。结果表明:菌株QI-1的最适生长和产酶温度均为5℃;最佳接种量为1%;发酵培养基的最适初始pH和最佳装样量分别为5和10%;盐度为2%时对菌株的生长和产酶最为有利;麸皮和醋酸钠分别为最佳N源和C源;添加0.75%酪蛋白时菌株QI-1胞外蛋白酶的活性最高;10 mmol/L Mg2+和0.5%Tween-80有利于产酶。正交试验结果表明:菌株Pseudoalteromonassp. QI-1产蛋白酶较佳培养基配方(g/L)为麸皮5,酵母粉2.5,酪蛋白3,MgCl2.6H2O 3,KCl 1.5;发酵液比酶活为166.20 U/mL,较优化前提高了约56%。     

光合菌群发酵玉米秸秆水解液产氢

以玉米秸秆水解液作为产氢底物,研究光合菌群产氢性能。考察了硫酸浓度、固液比、水解时间、水解温度等秸秆水解条件对产氢的影响,确定了最佳水解条件,并对不同脱毒方法进行了对比研究。结果表明,最佳的水解条件为硫酸浓度1%,固液比1:12,水解时间0.5 h,水解温度为110°C。采用Ca(OH)2脱毒方法的产氢效果要优于其他2种脱毒方法;NH4+在一定浓度范围内对该光合菌群产氢有促进作用。     

5′—磷酸二酯酶高产菌株的选育和发酵培养条件的优点

以ATCC14994为出发菌株,采用紫外线与亚硝基胍相结合的多次诱变育种,获得1株5′-磷酸二酯酶高产菌株HAT2228.通过单因子和正交试验对该菌株的产酶发酵条件进行了优化,优化发酵产酶条件为蔗糖5%,酵母膏0 3%,蛋白胨0.3%,K2HPO4 0.8%,KH2PO40.8%,MgSO4 0.2%,ZnSO4 0.2%,培养基起始pH6 0,接种量10%,培养温度30℃,摇床转速120r/min,发酵时间48h.在优化条件下,HAT2228的产酶水平达1 329u/ml.     

黄曲霉产木聚糖酶条件优化及酶解产物初步分析

一株能利用木糖及丰纤维素水解液产乙醇的黄曲霉Aspergillus flavus Z7具有产木聚糖酶的能力.通过单因素试验和正交试验优化了产酶培养基,得到最佳组分为玉米芯2%,尿素0.2%,酵母膏0.25%,K2HPO4 0.5%,NaNO,0.1%,MgSO4·7H2O 0.1%;单因素试验表明,用纱布代替塑料布密封摇瓶封口能显著提高产酶量;Z7在碱性条件下具有更强的产酶性能,在最优条件下发酵,能产生最大木聚糖酶活122.23IU/ml.通过薄层分析,验证了Z7产生的木聚糖酶具有水解木聚糖生成木糖及木寡糖的能力.     

5′-磷酸二酯酶高产菌株的选育和发酵培养条件的优化

以ATCC14994为出发菌株,采用紫外线与亚硝基胍相结合的多次诱变育种,获得1株5′-磷酸二酯酶高产菌株HAT2228.通过单因子和正交试验对该菌株的产酶发酵条件进行了优化,优化发酵产酶条件为:蔗糖5%,酵母膏0 3%,蛋白胨0.3%,K2HPO4 0.8%,KH2PO40.8%,MgSO4 0.2%,ZnSO4 0.2%,培养基起始pH6 0,接种量10%,培养温度30℃,摇床转速120r/min,发酵时间48h.在优化条件下,HAT2228的产酶水平达1 329u/ml.     

低温碱性蛋白酶菌株的筛选及产酶条件的研究

从 2 0株枯草芽孢杆菌筛选出了 1株产低温碱性蛋白酶菌株 ;并通过单因子实验、正交实验确定该菌株的最佳培养基为 :葡萄糖 8%,豆粕粉 6 %,Tween80 0 .0 3%,KH2 PO4 0 .0 6 %;确定了酶作用的最适条件为 30℃。     

产弹性蛋白酶菌种的筛选及发酵条件优化研究

从合肥肉联厂附近的土壤和污水中分离得到19株产弹性蛋白酶菌株,初步鉴定该菌株属于假单胞菌属.经过发酵复筛有三株产酶能力超过15u/mL.实验对菌株最佳产酶发酵条件进行了优化2%干酪素、0.5%葡萄糖、0.4%酵母膏、0.2% K2HPO4、0.01% MgSO4·7H2O;起始pH值7.0;最适发酵温度为30℃;装液量为25mL/250mL;该菌株在28h左右产弹性蛋白酶的量达18u/mL.     

BA-25菌株碱性纤维素酶产酶条件优化研究

试验研究了分离自烟草调制过程中的产芽孢细菌Bacillussp.BA-25菌株碱性纤维素酶产生的优化条件.结果表明:麸皮是最佳碳源,豆饼粉是最佳的氮源,且当碳氮比为2∶1时产酶活性最高;NaCl和KH2PO4对纤维素酶的合成具有重要作用,其适宜用量分别为0.5%～1.0%和0.1%;培养液的初始pH会极大地影响产酶活性,其最适pH为10.最优化的发酵工艺参数为:种子菌龄为24h,在300mL摇瓶中,装入30mL培养基培养温度为37℃,摇床转速为160r/min,在发酵24h后补充1%的葡萄糖,培养48h,该菌产碱性纤维素酶活力可以达到68.4U/mL.     

嗜线虫致病杆菌产生抗生素的培养基及条件*

本文对嗜线虫致病杆菌 (Xenorhabdus nematophilus)产生抗生素的发酵培养基和发酵条件进行了研究 ,同时对该菌代谢过程 p H值、还原糖、总糖、氨基氮与抗生素产量的关系进行了分析。通过筛选该菌对碳源和氮源的要求 ,用正交试验初步确定了该菌产素的最佳发酵培养基和条件为 :玉米粉 1% ,大豆粉 3% ,蔗糖 1% ,蛋白胨 1.5% ,KH₂ PO₄ 0 .0 2 % ,Mg SO₄ 0 .2 % ,活化剂     

Recent advances in the study of Kaposi's sarcoma-associated herpesvirus replication and pathogenesis

It has now been over twenty years since a novel herpesviral genome was identified in Kaposi's sarcoma biopsies. Since then, the cumulative research effort by molecular biologists, virologists, clinicians, and epidemiologists alike has led to the extensive characterization of this tumor virus, Kaposi's sarcoma-associated herpesvirus(KSHV; also known as human herpesvirus 8(HHV-8)), and its associated diseases. Here we review the current knowledge of KSHV biology and pathogenesis, with a particular emphasis on new and exciting advances in the field of epigenetics. We also discuss the development and practicality of various cell culture and animal model systems to study KSHV replication and pathogenesis.     

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     

Selection with two alleles and complete dominance

For a plant selection model with frequency-independent viabilities, fertilities and selfing rates, it is shown that apart from global fixation, for certain parameter combinations a protected polymorphism and facultative fixation (either allele may become fixed according to initial frequencies) may both occur. Facultative fixation requires different selling rates for the dominant and recessive type. Protection of the polymorphism requires resource allocation for male and female function. In this connection the problem of purely genetically caused population extinction is discussed.
For general frequency dependence and regular segregation, the chances for establishment of a completely recessive gene are compared to those of a completely dominant gene. It is proven that the process of establishment of the recessive gene, despite a fitness advantage, may be considerably endangered by drift effects if random mating prevails. The recessive gene may reach the same effectivity in establishment as a dominant gene, only if the recessive homozygote mates exclusively with its own type during the period of establishment.