产微生物絮凝剂的菌株筛选、鉴定及发酵条件优化

微生物絮凝剂是一类新型的水处理制剂,因其具有高效、无毒、易降解等特点,已成为水处理剂开发的研究热点。为了扩大微生物絮凝剂的种类,本研究从活性污泥和土壤样品中筛选絮凝剂产生菌,最终获得一株具有絮凝活性的菌株,通过16S rDNA鉴定,该菌株为蒙氏假单胞菌(Pseudomonas monteilii),因此命名为P. monteilii YR-1。利用单因素实验和正交试验对该菌株的发酵条件进行了优化,其最佳碳、氮源分别为25 g/L葡萄糖和2 g/L复合氮源(酵母浸粉:尿素:硫酸铵=5:5:2),培养基初始pH值为10,培养温度为28℃,发酵时间为72 h。在最佳培养条件下,其发酵液的絮凝率从37.68%提高到63.52%。这是关于蒙氏假单胞菌产絮凝剂的首次报道。     

Sphingomonas sp. X20絮凝特性及培养条件研究

目的:对分离筛选获得絮凝剂产生菌Sphingomonas sp.X20絮凝特性及培养条件进行研究.方法:采用单因素和正交实验确定最适产絮凝剂培养条件.结果:研究发现,菌株X20的微生物絮凝剂对高岭土悬液具有良好的絮凝效果,在温度为37℃、培养基初始pH7.0、摇床转速为100r/min条件下培养12h获得的絮凝剂絮凝活性最好,絮凝率达92.8%.正交实验结果表明,菌株Sphingomonas sp.X20产絮凝剂最佳培养基的组成:淀粉15g/L,NH4Cl 1.Og/L,KH2P04,2g/L,K2HP04 5g/L,NaC1 O.lg/L,MgS04·7H2O 0.2g/L,pH7.0.结论:菌株X20是一株高效的产絮凝剂菌,具有很好的应用前景.     

微生物絮凝剂产生菌的筛选及其絮凝特性初步研究

目的:从海口市白沙门污水处理厂活性淤泥中分离微生物絮凝剂产生菌,并对其絮凝特性进行初步研究。方法:稀释平板法进行菌株分离,高岭土悬浊法进行菌株的筛选以及菌株产絮凝剂特性、絮凝剂活性成分和热稳定性的研究;通过形态学和生理生化试验进行菌株的初步鉴定。结果:筛选到2株具有高絮凝活性的产生菌XN-6和XN-8,分别属于乳杆菌属(Lactobacillus sp.)和不动杆菌属(Acinetobater sp.)。菌株XN-6和XN-8发酵液絮凝率最高时,菌株XN-6的最佳pH值、最适温度和最佳转速分别为7、30℃、120r/min;XN-8的最佳pH值、最适温度和最佳转速分别为8、32℃、120r/min;菌株产絮凝剂活性成分热稳定性较差。菌株XN-6和XN-8单独处理污水的絮凝率分别为81.01%和76.78%,联合处理污水的絮凝率为79.08%,基本上不存在协同作用。结论:菌株XN-6和XN-8可作为原始菌株用于开发微生物絮凝剂,有望能应用于污水的处理。     

造纸废水微生物絮凝剂菌株的分离鉴定及特性

从造纸废水处理厂卡鲁赛尔(Carrousel)氧化沟的活性污泥样品中分离到了1株产絮凝剂的菌株B-6,经生理生化试验和16Sr DN A基因序列分析,鉴定为芽胞杆菌属(Bacillus sp.)。该菌株产生的絮凝剂具有良好的酸碱稳定性,在pH值1～5和7～11范围内,其絮凝活性维持在80%以上。优化该菌发酵上清液的絮凝条件,结果表明,加入5 mL的1%CaCl2,发酵上清液投加量为0.8 mL时,该菌株发酵上清液对高岭土悬浊液的絮凝率可达95.4%。     

微生物絮凝剂在甘蔗糖厂中的应用研究

经过初筛、复筛,从活性污泥中分离出一株富产絮凝剂并适用于甘蔗蔗汁絮凝澄清的微生物菌株A。根据生化和生理特征及光学显微镜和电镜扫描的形态观察,初步鉴定该菌株为轮枝孢属(Verticilliumsp.)。同时对菌株进行培养条件的初步实验,获得该菌株产絮凝剂的最佳培养条件为:pH6.0,28℃,140r/min,培养4d。最佳碳氮源分别为葡萄糖和牛肉膏。微生物发酵液在蔗汁沉降试验中的絮凝率为69.2%,清汁色值IU为87.4。     

常压室温等离子体诱变选育微生物絮凝剂高产菌株

目的:利用常压室温等离子体诱变技术诱变海洋地衣芽孢杆菌DHS-40,选育微生物絮凝剂高产菌株。方法:10μL发酵液(D600nm值为0.5~0.7),辐射距离为2 mm,气流速度为10.0 SLPM,辐射功率为100 W。结果与讨论:辐射时间60~240 s为菌株DHS-40的最佳诱变照射时间,共分离得到396株诱变株;经过初筛、复筛,共计筛选得到8株絮凝活性较高的诱变菌;经DHS-40突变菌株与原始菌株同步培养,比较生长状态与絮凝活性,获得2株絮凝活性较高的突变菌株90-102与120-24,同期絮凝活性优于原始菌株。     

微生物絮凝剂产生菌的筛选及培养条件的优化

目的:从好氧活性污泥、土壤和河泥中分离筛选具有较高活性的絮凝剂产生菌,并优化其培养条件;方法:通过常规分离获得目的菌株,运用单因素法考察培养时间、培养温度、发酵液初始pH值及摇床转速对菌株絮凝活性的影响;结果:得到了絮凝活性较高的菌株,经过优化得出,其最佳培养时间和温度分别为48h和30℃,发酵液最佳初始pH值为7.0,最佳摇床转速为120r/min,在最佳培养条件下,RF-32对高岭土悬浊液絮凝率为84.32%。结论:从活性污泥中可筛选出较高活性的絮凝剂产生菌,研究发现,菌株的絮凝活性与其生长量呈同步增长趋势,并在一段时间后达到一稳定值。培养时间、培养温度、发酵液初始pH值及摇床转速均能通过一定的作用因素对菌株生长情况产生影响,进而影响其絮凝活性。     

微生物絮凝剂产生菌的筛选和发酵条件研究

设计了微生物絮凝剂产生菌菌种筛选模型,并从土壤和活性污泥中筛选到５１株絮凝剂产生菌,经复筛获得两株絮凝活性较高的菌株,分别定名为Ｎｏｃａｒｄｉａ,ＪＩＭ－８９和ＪＩＭ－１２７。对两株菌的发酵条件,特别是培养基组成,进行了初步研究。两株菌所产生的絮凝剂,对大肠杆菌悬液２０ｍｉｎ的絮凝活性在１０００ｕ／ｍｌ,最高可达１２４８ｕ／ｍｌ。     

高效微生物絮凝剂D6对屠宰废水的应用研究

筛选出一株针对屠宰废水有高效絮凝活性的微生物絮凝剂产生菌,并对其所产微生物絮凝剂D6进行单因子絮凝条件优化和正交试验优化得到最佳絮凝条件。絮凝条件包括:微生物絮凝剂D6投加量、pH、金属离子种类、1%CaCl₂投加量。试验中发现碱性环境是微生物絮凝剂D6发挥絮凝活性的前提,表明微生物絮凝剂D6分子链的充分伸展对絮凝作用起决定因素,因此微生物絮凝剂D6的絮凝机理为吸附架桥作用。其最佳絮凝条件为微生物絮凝剂D6的投加量为25mL·L^-1,1%CaCl₂投加量55mL·L^-1,pH为8。在最佳絮凝条件下,絮凝率为96.6%,浊度去除率为97.8%,SS去除率为92.6%。     

两株微生物絮凝剂产生菌筛选与复合培养研究

目的:从土壤中筛选出微生物絮凝剂产生菌株进行复合优化培养得到高效絮凝剂。方法:采用平板划线法分离、纯化和筛选得到生长条件相互匹配的目的菌株,通过单因素和正交实验优化培养件,寻求絮凝活性最佳发酵条件。结果:发现菌株X-3和S-11菌株絮凝活性较高;复合菌株在牛肉膏-蛋白胨培养基中培养,初始pH为8,培养箱温度为35℃的条件下,培养时间72h,产生的分泌物对0.4g/L的高岭土悬浊液加3mg/L CaCl2助凝下絮凝率达到77.15%以上。结论:经鉴定X-3为德克斯氏菌属菌株,S-11为拜叶林克氏菌属菌株,匹配率为85%以上。     

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.