球形红细菌厌氧降解邻二氯苯及其机理研究

研究分析光合细菌球形红细菌在厌氧光照条件下降解邻二氯苯的条件和机理。结果表明, 在厌氧光照条件下球形红细菌的最佳生长和对邻二氯苯的最佳降解条件为：pH 7.0, 温度为30℃, 接种量10％。在最佳条件下, 邻二氯苯的去除率可达90％以上; 其降解中间产物主要有氯苯、4-羟基苯甲酸; 根据降解产物的分析, 推断球形红细菌降解邻二氯苯的机理主要是按照先脱掉一个氯原子生成氯苯, 然后氯苯进一步脱氯并通过4-羟基苯甲酸的代谢途径开环进行。     

球形红细菌厌氧降解2,4-二硝基甲苯

【目的】研究不同环境条件对2,4-二硝基甲苯(2,4-DNT)生物降解的影响。【方法】采用光合细菌球形红细菌在温度为30 °C的光照培养箱中厌氧降解2,4-DNT,并用高效液相色谱仪测定其浓度。【结果】去除2,4-DNT的最佳条件是初始浓度40 mg/L、初始pH 7.0和接种量15%。另外,2,4-DNT在菌体延滞期被细胞吸收,然后在指数期作为碳源被降解。2,4-DNT的去除率在72 h达到98.8%。从液相色谱图中观察到有2种中间代谢产物,但在120 h内产物被逐渐降解。2,4-DNT的去除动力学符合一级速率模型。【结论】不同条件下2,4-DNT的去除率表明球形红细菌能有效降解2,4-DNT。     

球形红细菌污泥颗粒化及降解氯苯

投加絮凝剂是促使微生物快速形成污泥颗粒的一种有效手段,通过研究在不同絮凝剂下生成的生物絮体的形态和沉降性能,推荐选用聚合氯化铝(PAC)作为促进光合细菌球形红细菌形成污泥颗粒的絮凝剂。PAC的最佳投加量范围为140-160mg/L,其中,PAC投加量150mg/L时,促进污泥颗粒化的效果最好。考察球形红细菌污泥颗粒降解氯苯的环境条件,结果表明球形红细菌污泥颗粒降解氯苯的最佳条件为好氧、pH7.0、30°C。     

厌氧丁草胺降解菌BAD-20的分离鉴定及降解特性研究

【目的】分离并鉴定能够降解除草剂丁草胺的厌氧微生物菌株,研究其厌氧降解丁草胺的特性和代谢途径,为深入研究丁草胺厌氧降解机制提供依据。【方法】以丁草胺为碳源作为选择压力从水稻田土壤中富集驯化丁草胺降解菌,利用16S rRNA基因系统发育分析结合菌株培养特征对降解菌株进行初步鉴定,利用液相色谱-时间飞行质谱(LC-TOF-MS)检测菌株降解丁草胺的代谢产物。【结果】筛选到一株降解丁草胺的厌氧细菌,命名为BAD-20,初步鉴定为嗜蛋白质菌属(Proteiniphilum),菌株BAD-20降解丁草胺的最适条件为温度30–35℃、pH 7.5–8.0和0–0.5%NaCl,在有氧条件下该菌不能降解丁草胺。最适条件下,菌株BAD-20在10d降解90%的20mg/L丁草胺。菌株BAD-20还能降解甲草胺、乙草胺、丙草胺,降解效率从高到低依次为甲草胺乙草胺丙草胺丁草胺,对这些氯乙酰胺除草剂的降解动力学符合一级动力学方程。鉴定到2个丁草胺降解代谢产物,分别是N-(2,6-二乙基苯基)-N-(丁氧甲基)乙酰胺(DEPBMA)和N-(2,6-二乙基苯基)乙酰胺(DEPA),表明菌株BAD-20降解丁草胺的起始步骤为脱氯,随后脱去N-丁氧甲基。【结论】本研究富集分离到一株降解丁草胺的厌氧细菌嗜蛋白质菌属(Proteiniphilum) BAD-20,为深入研究丁草胺厌氧降解机制及研发含丁草胺废水厌氧生物处理技术提供依据。     

质粒在大肠杆菌和沼泽红细菌之间的接合转移

人们以光合细菌中的紫色非硫光合细菌如球形红细菌和荚膜红细菌等为模型,在阐明光合作用机制等方面取得了很多成果,但对于紫色非硫光合细菌中的沼泽红细菌报道较少。直到1988年Harwood等人发现沼泽红细菌可以利用多种芳香族化合物如木质素单体、苯甲酸和4—羟基苯甲酸等作为唯一碳源进行光照厌氧生长或好氧生长,使沼泽红细菌成为研究该类化合物降解机制的一个良好模型。近年来,沼泽红细菌降解苯甲酸的途径已基本搞清。目前,研究集中于两个方向,一是有关酶类的提纯及性质研究,二是有关基因的克隆。     

氯酚类化合物的微生物降解研究进展

综述了近年在具有降解氯酚类化合物能力的微生物的筛选、氯酚类化合物的好氧和厌氧降解机制以及现代生物技术的开发利用研究．阐述了氯酚类化合物在不同条件下的降解路径．在好氧条件下,单氯酚和二氯酚在氧化酶的攻击下形成氯代邻二酚,邻二酚开环生成相应的氯代粘康酸或半醛,粘康酸内酯化过程中释放氯离子;高度氯代的化合物则是在氢氧化酶作用下生成氯代醌,并逐步脱去所有的氯原子生成苯酚后才开环．在厌氧或缺氧条件下,氯酚进行还原脱氯,在得到电子的同时去掉一个氯取代基．     

球形红细菌厌氧降解2,4-二硝基甲苯（英文）

【目的】研究不同环境条件对2,4-二硝基甲苯(2,4-DNT)生物降解的影响。【方法】采用光合细菌球形红细菌在温度为30°C的光照培养箱中厌氧降解2,4-DNT,并用高效液相色谱仪测定其浓度。【结果】去除2,4-DNT的最佳条件是初始浓度40 mg/L、初始p H 7.0和接种量15%。另外,2,4-DNT在菌体延滞期被细胞吸收,然后在指数期作为碳源被降解。2,4-DNT的去除率在72 h达到98.8%。从液相色谱图中观察到有2种中间代谢产物,但在120 h内产物被逐渐降解。2,4-DNT的去除动力学符合一级速率模型。【结论】不同条件下2,4-DNT的去除率表明球形红细菌能有效降解2,4-DNT。     

光合细菌对芳香族化合物厌氧降解的研究进展

许多被有毒性的芳香族化合物污染的环境实际上是缺氧的 ,因此芳香族化合物的厌氧降解逐渐引起人们的兴趣。芳香族化合物的厌氧还原降解机制从根本上不同于好氧条件下的氧化降解机制 ,而光合细菌一直以来是研究芳香族化合物厌氧降解的模式菌株。因此 ,从生理学、酶学及分子生物学角度出发概括了对光合细菌厌氧降解芳香族化合物的研究动态。     

厌氧微生物菌群XH-1对2,4,6-三氯苯酚的降解特性

有机污染物2,4,6-三氯苯酚(2,4,6-TCP)普遍存在于地下水和河流底泥等厌氧环境中。为了探究厌氧微生物菌群XH-1对2,4,6-TCP的降解能力,本研究以2,4,6-TCP为底物,接种XH-1建立微宇宙培养体系,并以中间产物4-氯苯酚(4-CP)和苯酚为底物分别进行分段富集培养,利用高效液相色谱分析底物的降解转化,同时基于16S rRNA基因高通量测序分析微生物群落结构变化。结果表明: 2,4,6-TCP(122 μmol·L^-1)以0.15 μmol·d^-1的速率在80 d内被完全降解转化,降解中间产物分别为2,4-二氯苯酚(2,4-DCP)、4-氯苯酚和苯酚,所有中间产物最终在325 d被完全降解。高通量测序结果表明,脱卤杆菌和脱卤球菌可能驱动2,4,6-TCP还原脱氯,其中,脱卤球菌可能在4-CP的脱氯转化中发挥重要作用,并与丁酸互营菌和产甲烷菌联合作用彻底降解2,4,6-TCP。     

深渊来源Citricoccus sp.strain NyZ702的分离培养及其降解4-羟基苯甲酸的特性

【背景】深渊沉积物中存在丰富的微生物细胞和活跃的微生物碳周转,因此,分离培养微生物资源对于认识深渊中的物质循环、能量代谢具有重要意义。芳香化合物在环境中广泛存在,基于组学分析揭示了深渊中具有潜在的芳香化合物代谢菌株,然而深渊来源的芳香化合物降解微生物纯培养和相关的代谢机理研究仍然缺乏。【目的】从马里亚纳海沟沉积物样本中分离培养具有降解芳香化合物能力的微生物,对其代谢途径、中间产物和降解酶活力进行初步鉴定。【方法】以4-羟基苯甲酸为唯一碳源对马里亚纳海沟沉积物样本中的降解菌株进行分离培养,结合形态观察、16S rRNA基因扩增与序列分析对菌株进行鉴定,通过底物生长实验验证其降解能力,通过高效液相色谱和超高效液相色谱-飞行时间质谱联用仪初步鉴定全细胞生物转化中间产物,利用紫外分光光度计测定其粗酶液催化4-羟基苯甲酸的活力,进而推测菌株降解4-羟基苯甲酸的代谢途径。【结果】从深渊沉积物中分离培养获得一株好氧细菌,16SrRNA基因序列分析显示该菌株隶属于柠檬球菌属(Citricoccus),命名为Citricoccus sp. strain NyZ702。该菌株在LB固体培养基上经30°C培养4 d后呈柠檬黄色、不透明、表面光滑、边缘整齐、凸出于培养基表面、直径约为1-2 mm的圆形菌落。扫描电镜表明菌体呈球形,直径为0.4-0.6μm,无鞭毛结构。该菌株为耐盐菌,最适生长盐浓度范围为2%-8%(质量体积分数)。该菌株可利用4-羟基苯甲酸为唯一碳源进行生长,可转化4-羟基苯甲酸至中间产物原儿茶酸,推测该菌株通过原儿茶酸途径降解4-羟基苯甲酸。菌株NyZ702的粗酶液具有4-羟基苯甲酸单加氧酶活力,对4-羟基苯甲酸的催化反应需要还原型烟酰胺腺嘌呤二核苷酸磷酸(NADPH)作为辅因子。【结论】从深渊沉积物样本分离得到一株4-羟基苯甲酸降解菌Citricoccus sp. strain NyZ702,该菌株以原儿茶酸为中间代谢产物降解4-羟基苯甲酸,丰富了深渊来源的微生物菌种资源,为深渊中的芳香化合物降解研究提供了一定的理论基础。     

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.