油脂酵母发酵木糖生产微生物油脂

目的用斯达油脂酵母(Lipomyces starkeyi)作为发酵菌株,以纯木糖溶液为油脂发酵原料,对L.starkeyi利用木糖积累油脂进行系统研究。方法 L.starkeyi于斜面培养基中活化后,接种于YPD液体培养基,于30℃、200 r/min摇床培养。在摇瓶中培养一段时间后,测定发酵液细胞浓度,离心发酵液收集细胞。将离心后得到的菌体加入木糖溶液重悬,并转接于含50 mL木糖溶液的250 mL摇瓶中进行发酵生产。结果相比一阶段法,两阶段发酵方法可以在更短的时间内达到较高的油脂含量,油脂含量能够达到细胞自身干重的60%以上。实验发现高菌龄酵母产油速度更快;并且初始木糖浓度高达120 g/L时,酵母细胞仍然能够高效合成油脂。结论 L.starkeyi能够有效利用木糖进行发酵产生油脂,是以木质纤维素为原料生产微生物油脂的优良菌种。     

酵母微生物油脂的生物合成研究

摘要：目的 微生物油脂可作为制备绿色能源生物柴油的原料。对酵母微生物油脂的生物合成方法进行研究。方法 以斯达油脂酵母Lipomyces starkeyi AS 2.1560为菌种进行微生物油脂生物合成。首先获得大量细胞,将细胞收集后,转移至葡萄糖溶液中进行油脂合成。结果 斯达油脂酵母可在不含有其他营养成分的葡萄糖溶液中快速合成油脂,细胞油脂含量可达到细胞干重的60%以上。菌龄对油脂生成影响不明显,糖浓度过高抑制油脂生成,40 g/L葡萄糖溶液中60 h合成油脂最多,达到65.2%,并有进一步积累的可能,在（0.5～6）×108个/mL,接种细胞的密度越大,油脂合成能力越低。合成油脂成分主要为棕榈酸和油酸。结论 斯达油脂酵母细胞增殖与油脂生物合成可分开进行,其油脂成分与普通动植物油脂成分相似。     

糠醛对粘红酵母生长与油脂积累的影响

为了探究纤维素水解液中常见的发酵抑制物糠醛对粘红酵母Rhodotorula glutinis生长与油脂积累的影响,对比了不同的糠醛浓度(0.1、0.4、0.6、1.5 g/L)下粘红酵母的生物量和油脂积累情况,并探究了1.0 g/L的糠醛对粘红酵母不同碳源(葡萄糖和木糖)利用的影响。研究表明,当糠醛浓度达1.5 g/L时,粘红酵母的延迟期延长至96 h,残糖高达17.7 g/L,生物量最高6.6 g/L,仅为正常积累量的47%,油脂含量也减少了约50%;以木糖为碳源时,糠醛对粘红酵母的抑制程度小于葡萄糖为碳源时的情况;在糠醛存在的逆境中,粘红酵母倾向于生成更多的18碳脂肪酸或18碳不饱和脂肪酸。     

不同营养元素限制对圆红冬胞酵母油脂生产的影响

以产油酵母圆红冬胞酵母（Rhodosporidium toruloides）作为研究对象,系统地研究了氮、磷、硫限制对其油脂积累的影响,并在3L生物反应器上考察了R.toruloides在C/P摩尔比为1 133.3时初始葡萄糖浓度对油脂生产的影响。结果表明：氮、磷、硫中任意一种营养元素受限,均能促使R.toruloides在胞内积累高于自身干重60%的油脂;通过改变培养基的组成,可以调节油脂中脂肪酸的构成,使油脂中饱和脂肪酸比例高于70%或不饱和脂肪酸比例高于60%。就油脂生产强度及转化效率而言,磷限制优于氮限制或硫限制。当C/P摩尔比相同时,初始葡萄糖浓度越低越有利于油脂生产。对采用不同原料生产微生物油脂的技术有一定指导意义。     

尼罗红染色法筛选产油酵母及定量检测胞内油脂含量的研究

【目的】建立产油酵母筛选以及胞内油脂含量测定的简便方法。【方法】利用尼罗红与胞内油脂成分结合后在紫外光照射下发出荧光且荧光强弱与油脂含量相关的原理。通过在添加尼罗红的培养基中培养酵母,并观察菌落荧光的方法对385株深海酵母进行产油脂菌株筛选,利用26S rDNA D1/D2区序列分析方法对筛选获得的产油酵母菌株进行鉴定,并以其中的一株高产油脂酵母(2A00015)为试验菌株,建立了一套尼罗红染色快速测定油脂含量的方法。【结果】获得22株产油酵母,其中油脂含量最高可达62.9%,经分子鉴定后显示这22株酵母分别属于(Candida viswanathii)、近平滑假丝酵母(Candidaparapsilosis)、粘质红酵母(Rhodotorula mucilaginosa)、汉逊德巴利酵母(Debaryomyceshansenii)、季也蒙毕赤酵母(Pichia guilliermondii)以及Rhodosporidium paludigenum酵母。尼罗红染色快速测定油脂含量方法的最佳检测条件为:菌悬液OD600小于1.2,尼罗红浓度0.5 mg/L,染色时间5 min,激发波长488 nm,发射波长570 nm。该测定方法得到相对荧光强度与称重法得到油脂含量呈正相关性,R2=0.9637。     

皮状丝孢酵母B3利用木薯淀粉发酵生产微生物油脂

对皮状丝孢酵母B3以木薯淀粉水解液为碳源发酵生产微生物油脂培养条件进行了优化,并在2 L发酵罐中对菌体生长和油脂积累进行了考察。摇瓶实验表明,木薯淀粉水解液的浓度高于90 g/L时不利于菌体的生长和油脂积累,皮状丝孢酵母B3发酵生产微生物油脂的最适氮源及其浓度、最适C/N比和pH分别为酵母提取物3.0 g/L、116、6.0,在此条件下培养144 h菌体生物量、油脂产量和油脂含量分别达到15.2 g/L、6.22 g/L和40.9％;在2 L发酵罐中分批发酵44 h后菌体生物量、油脂产量和油脂含量分别达28.7 g/L、12.27 g/L和42.8％。以皮状丝孢酵母B3所产油脂制备生物柴油,其主要组成包括棕榈酸甲酯、硬脂酸甲酯、油酸甲酯、亚油酸甲酯等,且理化特性符合相关国家标准,可作为一种有潜力的化石燃料替代品。     

Cryptococcus curvatus O3酵母菌培养及产油脂特性

生物柴油的发展, 导致全球油脂供求紧张。微生物油脂的甘三酯组成与植物油类似, 发展微生物油脂可部分缓解植物油脂供应压力。本文研究了Cryptococcus curvatus O3酵母利用葡萄糖为碳源生长和积累油脂的特性。Cryptococcus curvatus O3酵母在培养过程中能适应间歇式碳源流加方式达到高密度培养的目的, 但在相同培养条件下, 不同氮源能影响其代谢过程中糖到油脂转化的脂肪系数。Cryptococcus curvatus O3酵母利用葡萄糖作为碳源在30°C下摇瓶发酵, 菌体生物量为51.8 g/L, 油脂含量达65.1%。脂肪酸组成分析结果表明, 菌油富含饱和及低度不饱和长链脂肪酸, 其中饱和脂肪酸之和占总脂肪酸组成的64%左右, 其脂肪酸组成类似于可可脂, 这些结果对于利用产油微生物转化生物质获取如类可可脂等具有高附加值油脂的研究具有重要意义。     

色醇对斯达氏油脂酵母产油能力的影响

研究在发酵培养基中添加色醇对斯达氏油脂酵母发酵的影响。结果表明, 在接种后0 h或12 h时添加色醇, 能够明显抑制菌体生长和油脂积累; 而在培养24 h或36 h添加, 能够明显促进菌体生长, 并增强菌体对底物利用率。与对照组比较, 在36 h添加100 mmol/L色醇, 生物量、油脂量和脂肪系数分别增加7.4%、13.9%和14.2%, 发酵时间缩短13.3%, 明显提高了油脂生产效率。气相色谱分析表明, 添加色醇对菌油脂肪酸组成及其相对含量无显著影响。实验结果有助于建立调控油脂发酵的新策略, 具有重要的理论和工程应用意义。     

斯氏油脂酵母降解百草枯的效率及影响因素

本文研究了温度、pH值、葡萄糖浓度对斯氏油脂酵母降解百草枯的影响。结果表明在温度为30℃,pH值6~7,葡萄糖浓度大于6%的培养条件下,斯氏油脂酵母降解百草枯的效率最高。斯氏油脂酵母在无氮培养基中的生长速度与百草枯的降解效率呈正相关。     

油菜油脂研究进展

油菜（Brassica napus）是世界范围内重要的油料作物,是植物油脂的第三大来源,其种植面积和总产量在油料作物中占有相当大的比例。我国油菜品种油脂含量普遍较国外低2—5个百分点,而油脂含量每增加1个百分点对产油量提高的贡献,相当于菜籽产量提高2．5个百分点。因此提高油菜油脂含量是解决油菜生产效益低的重要途径之一。本文综述了油菜油脂研究的状况,包括油脂积累的遗传学基础、油脂合成途径和调控、油脂含量的QTL定位及油脂含量与品质性状的遗传相关性,同时展望了油菜油脂研究前景,以期为油菜油脂含量的品种改良提供科学指导。     

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.