混菌状态对新菌系产生VC前体KGA的影响

通过测定氧化葡萄糖酸杆菌产酸变化,研究了新菌系混菌状态对产酸的影响。结果显示：新混菌体系中,种液KGA为4.1-5.5mg/ml,混合菌菌群氧化葡萄糖酸杆菌/掷孢酵母为26-35：1,混菌生物量达0.46-0.60(OD值）,有利于二菌在发酵中相互协调,促进产酸,调节接种生物量可增加产酸速度,缩短产酸周期,但不影响最终产酸量。     

玉米浆对Vc二步发酵产2-酮基-L-古龙酸影响的研究

通过在培养基中添加不同量的玉米浆,研究其对氧化葡萄糖酸杆菌（俗称小菌）生产Vc前体2-酮基-L-古龙酸的影响,并研究玉米浆成分中的12种主要氨基酸对小菌产酸的影响。结果表明：每100 mL发酵培养基中添加2.5 g左右过滤除菌玉米浆时,2-酮基-L-古龙酸产量高达26.84 mg/mL,小菌活菌数为不添加玉米浆时小菌单菌发酵下的9.74倍。过量玉米浆抑制小菌产酸。12种氨基酸单独与氧化葡萄糖酸杆菌发酵培养及全部混合后与氧化葡萄糖酸杆菌发酵培养对产酸及菌体生长无影响。     

混合培养中巨大芽孢杆菌对氧化葡萄糖酸杆菌的作用

为查明维生素Ｃ二步发酵混合培养中巨大芽孢杆菌与氧化葡萄糖酸杆菌间的关系,通过生长曲线测定、静息细胞实验及摇瓶发酵实验研究了巨大芽孢杆菌对氧化葡萄糖酸杆菌生长和产生２－酮基－Ｌ－古龙酸作用的影响;采用超滤分离、凝胶层析及聚丙烯酰胺凝胶电泳技术对巨大芽孢杆菌胞外液中具有促进氧化葡萄糖酸杆菌产酸作用的活性物质进行了分离和纯化。结果表明,大菌胞内液和胞外液均可促进小菌生长,大菌胞外液中具有该作用的组分分子     

生黑葡萄糖酸杆菌转化高浓度山梨醇的条件优化

目前,国内维生素C主要采用二步发酵法生产,其中第一步为生黑葡萄酸杆菌(Gluconobacter melano-genus)将D-山梨醇转化为L-山梨糖。考察了该菌株在提高培养基中山梨醇浓度时的发酵特性和发酵条件。实验室摇瓶实验结果显示,通风量、发酵前期及后期pH值控制、接种种液类型都影响高浓度山梨醇摇瓶发酵的转化率。以35%山梨醇浓度发酵液做种子液明显优于生产上采用的三级种子液(12%~17%山梨醇浓度),培养基前期pH值5.0~6.0,后期pH值4.2~3.9,装液量180 mL,发酵周期在30 h之内,山梨醇转化率在98%以上。培养基山梨醇浓度由23%提高到35%,发酵周期延长8 h。上述实验结果对指导生产工艺优化具有重要意义。     

两株内生芽孢杆菌对盐胁迫下大豆幼苗超氧化物歧化酶和过氧化物酶活性影响

【背景】盐胁迫环境严重影响大豆幼苗生长,内生菌可提高作物的抗逆性。【目的】探究接种内生枯草芽孢杆菌127和解蛋白芽孢杆菌133对盐胁迫下大豆幼苗体内超氧化物歧化酶(superoxide dismutase,SOD)和过氧化物酶(peroxidase,POD)活性的影响。【方法】以“徐豆20”为实验材料,采用盆栽实验法,设置对照组、盐胁迫组和盐胁迫接菌组,在人工气候培养条件下,用不同NaCl浓度(50、100、150、200、250和300 mmol/L)处理大豆幼苗,并接种不同OD600值(OD0.33、OD0.50和OD0.75)的菌悬液。【结果】培养14 d,接种枯草芽孢杆菌127的菌悬液OD0.33和OD0.75分别在盐浓度300 mmol/L和100 mmol/L时,SOD活性均为1.04 U/g-FW;接种解蛋白芽孢杆菌133的菌悬液OD0.50在盐浓度300 mmol/L胁迫下POD活性最高为7 820 U/(g·min),对大豆幼苗修复效果较显著。培养28 d,接种枯草芽孢杆菌127的菌悬液OD0.50,在150 mmol/L时SOD活性最高(0.88 U/g-FW);接...     

维生素C发酵中伴生菌对氧化葡糖杆菌的影响

通过分析维生素C二步发酵过程中活菌数、产酸量、pH、糖酸转化活力等 ,研究了蜡状芽孢杆菌 (俗称大菌 )对氧化葡糖杆菌 (俗称小菌 )生长和产酸的影响。结果表明 ,在大菌存在情况下 ,小菌的活菌数约为单菌培养条件下的 5倍 ,产酸量为单菌培养条件下的 2～ 3倍 ,糖酸转化活力为单菌培养条件下的 2～ 3倍 ,提示在混合菌发酵条件下大菌仅仅是通过刺激小菌的生长而促进小菌产酸。用小菌休止细胞进行的糖酸转化实验结果也表明 ,无论大菌的发酵上清液还是破碎的菌体 ,都未发现对小菌产酸产生直接影响。     

VC二步发酵新组合菌系的研究

选用苏云金芽孢杆菌与氧化葡萄糖酸杆菌组成一新组合菌系 ,其摇瓶发酵转化率较原菌系提高 4 .83% ,且具有耐受高浓度 (10 % )山梨糖的特性。在 4m3 发酵罐中 ,连续 4批发酵平均转化率较对照菌系提高 8.16 % ,周期缩短 2 3.7%。新菌组合系的发酵转化率与玉米浆浓度成正相关性 ,尿素浓度x2 =1.4 5 % (g/ 10 0mL)时 ,转化率达最大。     

耐高温菌的分离及在固态发酵上部烟叶中的应用

从上部低次烟叶中筛选出耐高温淀粉酶产生菌GW-2和耐高温蛋白酶产生菌GW-3,通过对菌落的形态观察、16S rRNA的鉴定和同源性分析,初步确定GW-2为解淀粉芽胞杆菌,GW-3为枯草芽胞杆菌。对上部低次烟叶进行双菌种固态发酵,并优化发酵条件,最佳发酵条件:GW-2菌悬液(OD600=1)接种量为7.5 m L/g,GW-3菌悬液(OD600=1)接种量为10 m L/g,物料填充度为500 m L三角瓶中装50 g烟叶干基,当烟叶发酵水分质量分数为45%时,48℃发酵5 d。在该发酵条件下,上部低次烟叶的淀粉降解率为22.33%,蛋白质降解率为16.74%。烟叶淀粉和蛋白质的质量分数较大幅度下降,其含量指标接近优等烟叶的含量。该发酵方式比传统的贮存式烟叶发酵大大缩短了发酵时间。     

皂荚种子发酵工艺优化及其保湿功效探究

目的：通过微生物发酵法提取皂荚种子多糖，得到一种提取简单、成本低、安全性高，同时具有良好保湿效果的皂荚种子多糖发酵产物滤液。方法：筛选纳豆芽孢杆菌（Bacillus natto）进行生物发酵，通过单因素分别优化皂荚种子发酵过程中的料液比、发酵温度、发酵时间以及发酵菌接种量，以多糖提取率为评价指标探究最优结果。同时选择符合要求的志愿者分别进行人体斑贴实验和皮肤含水量测试，探究皂荚种子发酵产物的安全性及其保湿功效。结果：皂荚种子发酵工艺设定为料液比1∶40 (g/mL)，发酵温度40℃，发酵时间60 h，发酵菌接种量1.0%，所得的多糖提取率为31.8%，斑贴实验48 h内未出现不良反应，皮肤含水量测试结果显示，多糖含量在3.18%和6.36%的皂荚种子发酵产物滤液可显著提高皮肤含水量。结论：纳豆芽孢杆菌发酵所得的皂荚种子发酵产物滤液多糖含量显著提高，且无刺激性，具有良好的保湿功效，在日化领域原料开发中有较高的开发应用价值。     

贯叶连翘总提取物对黄色短杆菌的抗菌作用

报道了贯叶连翘总提取物作用于黄色短杆菌并经光照和未光照处理后对该菌的抗菌作用,目的是探讨贯叶连翘总提取物在光照和非光照处理时抗菌作用的异同。采用光密度(OD)值、活菌数(CFU)、最低杀菌浓度(MBC)值检测方法,测定了在12h的培养过程中,提取物作用时黄色短杆菌的OD640nm值、CFU、MBC值。结果表明提取物对该菌有很强的抑菌和杀菌作用,且这两种作用与其浓度有关,不需光照。     

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.