融粘帚霉对葛根素的生物转化研究

采用融粘帚霉AS3.3987对葛根素进行微生物转化,生成的主要产物经分析鉴定是3′-羟基葛根素.采用高效液相色谱方法,以XDB-C18为色谱柱,甲醇:水(27∶73)为流动相,检测波长为254 nm,测得在160 r/min、30 ℃的转化条件下,底物加量为400 μg/mL,转化时间为36 h时,3′-羟基葛根素得率...     

稻曲病菌厚垣孢子壁黑色素提取方法研究

探究稻曲病菌（Ustiloginoidea virens（Cooke） Takahashi）厚垣孢子壁黑色素的最佳提取方法,采用以HCl为提取剂的酸提法和以NaOH为提取剂的碱提法,对该病菌黑色和黄色2种厚垣孢子壁的黑色素进行提取,用3因素3水平进行正交设计试验,结果表明以NaOH作提取剂为佳,其提取黑色素效果最佳的组合条件为3 mol/L NaOH、2 mol/L HC l、水浴温度80℃、水浴时间120 min。     

绿盖粉孢牛肝菌中一个新的甾体糖苷

从绿盖粉孢牛肝菌（Tylopilus virens）中分离得到一个新的麦角甾烷型甾体糖苷,其化学结构通过波谱学方法鉴定为：（22E,24R）-麦角甾-7,22-二烯-5α,6β-二醇-3β-O-[3-（3-苯基丙酰氧基）]-β-D-葡萄吡喃糖苷,命名为tylopiloside（1）,同时,其苷元cerevisterol（2）也从该菌中分离得到。值得注意的是,这种糖片段上有芳环取代的烷酰氧基基团的麦角甾烷型甾体糖苷为真菌中首次报道。     

Genetic Diversity of Rice False Smut Fungus, Ustilaginoidea virens and its Pronounced Differentiation of Populations in North China

Rice false smut caused by Ustilaginoidea virens is an important constraint affecting rice yield and quality in Asia. In China, rice false smut is especially severe in the japonica rice-growing areas in the North China. Nothing is known neither about the diversity of the pathogen in this region nor about the characteristic of its local population. In this study, 110 U. virens isolates sampled from Liaoning and Beijing of North China were analysed using amplified fragment length polymorphism (AFLP) markers to primarily understand the genetic diversity of this pathogen and its population characteristics. At the genetic distance of 0.32, all isolates were divided into two groups. Group A consists of two subgroups differentiated at the genetic distance of 0.55, subgroup 1 included all isolates from Liaoning with an average genetic similarity over 0.82 and subgroup 2 included 27 isolates from Beijing with similarity of 0.74. Group B consists of 28 isolates from Beijing having a diversity of 0.054. The isolates from the Liaoning province, where rice false smut has generated different take-all epidemic for 20 years, showed a genetic diversity of 0.305, which was approximately equally distributed within and among populations. Whereas genetic diversity was 0.458 among isolates from Beijing, an extremely high level of genetic differentiation among 55 isolates was observed in this disease hotspot. Our results suggested that the populations among different locations where sexual stage of the pathogen was rare to be found within ecological region were similar, and the variation of this pathogen has mainly arisen via asexual mechanisms. The migration through human activities in breeding perhaps provides a means of transporting the pathogen from one region to another.     

Simple Synthesis of Climacostol,a Defensive Secretion by the Ciliate Climacostomum virens

Climacostol {1,3-dihydroxy-5-[(Z)-2'-nonenyl]benzene,1}, a defensive secretion by the protozoan ciliate Climacostomum virens against predators, was synthesized in a 43% overall yield in three steps by starting from methyl 1,3-bis(tert-butyldimethylsilyloxy) phenylacetate (3).     

共培养条件下绿木霉对褐环乳牛肝菌产酶的诱导效应

为了探讨绿木霉与褐环乳牛肝菌的互作机理,在体外共培养条件下,采用光学显微镜和扫描电镜对二者生长重叠部分进行体外观察,发现二者生长无相互影响,在营养生长方面几乎不存在竞争关系。为进一步揭示绿木霉与褐环乳牛肝菌的互作机制,采用体外诱导和生物化学等方法,向褐环乳牛肝菌发酵液中加入灭活绿木霉菌丝诱导物,每天对发酵液中的多酚氧化酶、几丁质酶、漆酶和中性蛋白酶等酶活性进行检测。试验结果表明,绿木霉诱导褐环乳牛肝菌产漆酶能力最强;在整个共培养过程中,多酚氧化酶和漆酶活力始终处于较高水平,在诱导培养第6天,这两种酶活性升至最高,分别达到25.2U/mL和1 580U/mL;灭活绿木霉菌丝对褐环乳牛肝菌几丁质酶的诱导具有“瞬时性”,在诱导培养第2天即检测到较高的几丁质酶活性;中性蛋白酶的活性变化基本上呈先上升后下降的规律,且能增大褐环乳牛肝菌中性蛋白酶的固有产量,形成“叠加效果”。综上所述,绿木霉对褐环乳牛肝菌几乎不存在营养竞争关系,但其灭活菌丝体对褐环乳牛肝菌发酵液的多种酶活性存在诱导增效作用。     

绿粘帚霉菌株发酵液抗真菌活性及稳定性测定

采用杯碟法测定绿粘帚霉（RCEF4099）菌株的发酵液对8种植物病原真菌的抗菌活性。结果表明RCEF4099菌株发酵液对5种供试病原真菌的抑菌圈直径在18mm以上。对菌株发酵液的稳定性测定结果表明菌株转接6代之前,活性稳定,从第7代开始其活性缓慢降低,第10代的抑菌圈直径仅比出发菌株减少了1．7mm。RCEF4099菌株发酵液有较好的热稳定性,发酵液加热到60％仍有较高活性。该菌株的发酵液对酸的稳定性较好,抑菌活性最强的pH值为4。     

Production of TMC-151, TMC-154 and TMC-171, a new class of antibiotics, is specific to ‘Gliocladium roseum’ group

A novel class of fungal metabolites, TMC-151, TMC-154, and TMC-171 series compounds, was found exclusively inGliocladium catenulatum, Clonostachys rosea and closely related strains. These compounds were not detected in any other fungi examined. The production spectrum of each component was correlated to the morphology of the secondary conidiophores and the conidia. TMC-151 was limited toClonostachys rosea (formerlyG. roseum) forming navicular or reniform conidia orG. catenulatum with gray-green conidial masses, whereas TMC-154 and 171 were limited to the strains closely related toGliocladium roseum, which grew more slowly and formed more symmetrical conidia.     

Foliar Application of Fungal Biocontrol Agents for the Control of White Mold of Dry Bean Caused by Sclerotinia sclerotiorum

Field experiments were conducted during 1992–1994 to evaluate the effectiveness of five indigenous fungi for control of white mold (Sclerotinia sclerotiorum) of dry bean (Phaseolus vulgaris). The five fungi consisted of one antagonist, Epicoccum purpurascens, and four mycoparasites, Coniothyrium minitans, Talaromyces flavus, Trichothecium roseum, and Trichoderma virens. Spore suspensions of each fungus were sprayed onto bean plants two or three times during the early bloom to midbloom period. Incidence of white mold of dry bean was significantly reduced by all biocontrol agents. C. minitans and E. purpurascens, the most effective agents, reduced the proportion of plants infected by an average of 56 and 43%, respectively (P < 0.001). C. minitans was the only biocontrol agent recovered consistently from sclerotia and diseased seed present in harvested samples. It was recovered at similar frequencies in samples from all treatments. Of the sclerotia of S. sclerotiorum collected from harvested seed, 59% were infected by C. minitans in 1993 and 20% were infected by C. minitans in 1994. In three additional trials in 1994, comparing C. minitans with the fungicide benomyl, the fungus was not effective in any of the experiments, whereas benomyl reduced disease incidence relative to the control in one trial. The study suggests that, among the five indigenous fungi, C. minitans is the most promising agent for control of white mold of dry bean under Canadian prairie conditions.