产黄青霉细胞分化与青霉素生物合成的相关性

目的：通过菌丝细胞在发酵阶段中的分化规律，去了解青霉素生物合成能力的相关性。方法，应用相差显微镜观察产黄青霉在插瓶发酵培养时菌丝形态分化的不同发育阶段。结果：它们分别完成了三个生活循环，每个生活循环中不同分化阶段的菌丝结构东同，功能也不同，结论：根据不同发酵阶段的菌丝细胞分化，可了解和掌握发酵规律。     

生物合成青霉素的第一阶段中产黄青霉菌丝产青霉素量的研究

青霉素形成过程的两个阶段,早就表明是不一定的,而且在创造适当的条件时菌丝的产青霉素量在发酵全过程中保持稳定。 本文的目的是研究通常两个阶段的第一个阶段菌丝产青霉素量低的原因。 根据Беккер报导,产量低同菌丝的菌龄有关系。处在Ⅰ一Ⅲ发育阶段的年轻的青霉菌菌丝不能合成青霉素;在Ⅳ—Ⅵ成熟阶段的菌丝具有最高的产量。Прокофьева-Бельговская用某些放线菌类产生的一些抗生素的例子表明,菌丝只有过渡到第Ⅲ个生长阶段时才开始合成抗生素。     

头孢菌素C的生产模型及其在分批加料发酵中的应用

数学模型如与适当的方法相结合可以成为改进发酵工艺的有效工具,为此数学模型必须能够定量地反映发酵过程的变化。作者根据顶头孢霉发酵过程以下特点提出本文的模型: 1.顶头孢霉在沉没培养过程中主要具有三种类型的细胞,即菌丝、膨胀的菌丝碎片及节孢子。在生长前期表现为菌丝型,随着时间的延长一些菌丝分化为膨胀的菌丝碎片。当这种膨胀的菌丝碎片在培养基中占优势时则大量合成头孢菌素C,而且高产菌株的膨胀菌丝碎片比野生菌株多;     

青霉素产生菌产黄青霉绿色孢子菌种77-5-327和79-6-55发酵液中前体含量的估算和加量问题的探讨

青霉素发酵生产过程中,前体的毒性问题曾有不少报道。当前体浓度为500微克/毫升时,不利于孢子发芽和年青菌丝的生长,超过1000微克,毫升时,就导致青霉菌过早自溶并抑制了青霉素的合成。前体浓度在500～1000微克/毫升时,青霉素合成最多。     

链霉菌抗生素生物合成和孢子形成的遗传控制

一、引言链霉菌具有两个与放线菌以外的大多数细菌明显不同的特征:形态分化复杂的生活周期,包括从休眠孢子,经过营养菌丝到气生菌丝又重新形成孢子的整个过程;产生无数的抗生素和其他次级代谢物,这些物质是属于在其他生物中常常找不到的化学种类。链霉菌以相当多的基因来控制其生命周期的这两个方面。抗生素是逐步合成的代谢产物,每一步都需要约10～30个基因来决定其结构和起自我保护作用抗性基因,以及控制结构基因活性的调控基因,并使它们随特性生存需要给予表达;这常常与活性营养生长     

卡那霉素链霉菌在摇瓶培养中的溶氧研究

微生物在发酵过程中,不断消耗发酵液中的溶解氧,发酵液中溶氧量等于供氧减去耗氧。由于在发酵的各阶段微生物在发酵液中单位容量内细胞数和呼吸强度不同,所以耗氧也不同。一般说来,发酵开始时,虽然细胞的呼吸很强,但菌丝量很少,所以微生物在     

抗生素产生菌链霉菌基因表达与调节

链霉菌属于革蓝氏阳性细菌,具有两个不同于其他原核生物的特点:一是形态发育过程中,形成菌丝分枝及孢子;二是能够合成许多不同的代谢物.至今链霉菌仍是抗生素和其他生理活性物质最丰富的微生物来源.链霉菌具有显著的分化基因表达能力,从它的发育史可以表明.例如孢子含有的基因产物在其发芽的菌丝中是没有的.菌丝的分枝可能是与使细胞壁肽聚糖链重排的酶活性有关,形态遗传的特性是气生菌丝形成分隔期特殊基因活性的反映.     

变温培养对青霉素发酵的影响

在青霉素发酵过程中的不同阶段采用不同的培养温度,通过实验考察其对青霉素发酵的影响。实验结果表明,变温培养的发酵水平要高于２５℃恒温培养的发酵水平。     

应用蔗糖梯度密度分级离心的方法研究不同发酵条件下艮他霉素产生菌的生长情况

艮他霉素(GM)产生菌的深层发酵同其它抗生素发酵一样是复杂的,在生长周期的不同阶段中,尽管在同一时间内测定,所观察到的菌丝也是处于不同的生长状况。细胞学的研究有时不能解决生产实践的要求——什么样的细胞具有最高的生产能力。本文作者应用蔗糖梯度密度((?))分级离心的方法,分析不同培养条件下GM产生菌的菌丝分布,研究菌丝分布与生产力之间的关系,借以评价培养物产生抗生素的能力。分级离心的蔗糖梯度浓度为50,45,40,35,30,25%。蔗糖溶液冷却至4℃后,小心     

产黄青霉形态的显微图像分析研究

利用显微图像分析法对产黄青霉的菌丝形态进行了定量研究，并统计分析了青霉素发酵过程中菌线形态的变化规律，具体对菌丝总长度、菌丝生长期的菌丝生长单位、菌丝变异率和菌丝自溶率进行了定量分析。     

Antifungal properties of surangin B, a coumarin from Mammea longifolia

The natural product electron transport inhibitor surangin B was examined for its ability to inhibit in vitro mycelial growth and spore germination in several species of fungi. As an inhibitor of mycelial growth, surangin B showed strongest activity against Rhizoctonia solani (IC50 = 3.8 microM) and Botrytis cinerea (IC50 = 11.2 microM). Inhibitory effects were less pronounced in Alternaria dauci, Fusarium oxysporum and Penicillium sp. (IC50 values > 30 microM) and absent in Trichoderma harzianum. Surangin B reduced the level of spore germination in Fusarium oxysporum (IC50 = 2.3 microM) and Botrytis cinerea (IC50 = 1.4 microM), although Alternaria dauci was considerably more tolerant of this coumarin (IC50 = 500 microM). Our results indicate that surangin B may have potential as an antifungal agent.     

The Antifungal Activity of Glycosmis calcicola and G. rupestris Extracts

The antifungal activity of Glycosmis calcicola B.C. Stone and G. rupestris extracts was evaluated using poison food and spore germination techniques. The CHCl₃ extract of G. calcicola has been shown to be most effective in inhibiting mycelial growth, sporulation, and spore germination on three fungal pathogens of chili. The antifungal compounds were identified as flindersine and desmethoxyanthophylline and their structures were determined by spectroscopic methods and comparison with reported data.     

Isolation and in vitro cultivation of Auriculoscypha anacardiicola D.A. Reid et Manim., an insect-associated and potentially medicinal fungus from India

Auriculoscypha anacardiicola, an obligate insect-associate and a potential medicinal fungus, is isolated and studied in vitro. Suitable methods for isolation and cultivation of the fungus have been developed. Incubating spore deposits made to fall from basidiomata on tap water agar seems to be the best method for developing cultures. Successful isolations were also accomplished from infected coccids. Cultures could not be developed from single basidiospores and from tissues of the basidiomata. Although production of ballistospores and blastospores as well as germ tube formation were observed at the time of germination of basidiospores, budding blastospores alone produced mycelial cultures. Observations such as the inability of single basidiospores to germinate, emergence of mycelium from a spore deposit, and the apparent conjugation of yeast cells indicate that dikaryotization resulting from fusion of compatible yeast cells is essential for development of mycelium in A. anacardiicola. The fungus grew well on all complex media tested. It seems that a purely synthetic medium devoid of any growth factors cannot support the growth ofA. anacardiicola and yeast extract seems to provide the required growth factors.     

Antifungal Activity of Quinofumelin against Fusarium graminearum and Its Inhibitory Effect on DON Biosynthesis

Fusarium graminearum, causal agent of Fusarium head blight (FHB), causes a huge economic loss. No information is available on the activity of quinofumelin, a novel quinoline fungicide, against F. graminearum or other phytopathogens. In this study, we used mycelial growth and spore germination inhibition methods to determine the inhibitory effect of quinofumelin against F. graminearum in vitro. The results indicated that quinofumelin excellently inhibited mycelial growth and spore germination of F. graminearum, with the average EC₅₀ values of 0.019 ± 0.007 μg/mL and 0.087 ± 0.024 μg/mL, respectively. In addition, we found that quinofumelin could significantly decrease deoxynivalenol (DON) production and inhibit the expression of DON-related gene TRI5 in F. graminearum. Furthermore, we found that quinofumelin could disrupt the formation of Fusarium toxisome, a structure for producing DON. Western blot analysis demonstrated that the translation level of TRI1, a marker gene for Fusarium toxisome, was suppressed by quinofumelin. The protective and curative assays indicated that quinofumelin had an excellent control efficiency against F. graminearum on wheat coleoptiles. Taken together, quinofumelin exhibits not only an excellent antifungal activity on mycelial growth and spore germination, but also could inhibit DON biosynthesis in F. graminearum. The findings provide a novel candidate for controlling FHB caused by F. graminearum.     

Effect of Zataria multiflora Boiss. essential oil on growth and aflatoxin formation by Aspergillus flavus in culture media and cheese

The effect of Zataria multiflora Boiss. essential oil (EO) against growth, spore production and aflatoxin formation by Aspergillus flavus ATCC 15546 was investigated in synthetic media as well as Iranian ultra-filtered white cheese in brine. EO effectively inhibited radial growth and spore production on potato dextrose agar (PDA) in a dose-dependent manner. At 200 ppm, the radial growth and sporulation reduced by 79.4% and 92.5%, respectively. The growth was completely prevented at EO ? 400 ppm on PDA, and minimum fungicidal concentration (MFC) of the oil was estimated at 1000 ppm. The oil also significantly suppressed mycelial growth and aflatoxin synthesis in broth medium at all concentrations tested (P < 0.05). At 150 ppm of EO, the mycelial growth and aflatoxin accumulation reduced by 90% and 99.4%, respectively. The EO at all concentrations tested, had an inhibitory effect against radial fungal growth and aflatoxin production by A. flavus in cheese. However, no concentration of EO examined was able to completely inhibit the growth and aflatoxin production in cheese. The results suggested the potential substitution of the antifungal chemicals by this EO as a natural inhibitor to control the growth of molds in foods such as cheese.     

灵芝孢子多糖LPS3对Lactacystin诱导PC12细胞损伤的影响

目的探讨灵芝孢子多糖LPS3对蛋白酶体抑制剂Lactacystin诱导PC12细胞损伤的影响。方法体外培养PC12细胞,建立Lactacystin诱导PC12细胞损伤的模型,用CCK-8法检测细胞活力,Annexin V-FITC/PI流式细胞法检测细胞调亡,免疫荧光法检测胞浆中α-synuclein聚集物的生成。结果模型组经20μmol·L-1Lactacystin处理24 h后,PC12细胞活力比空白对照组降低,仅为64.7%;经不同浓度的灵芝孢子多糖LPS3预处理后,细胞活性明显提高,且其细胞活性随多糖浓度升高而升高;Lactacystin可以诱导PC12细胞凋亡,处理24 h后细胞凋亡率为45.40%,经灵芝孢子多糖LPS3预处理后,细胞凋亡率明显降低;PC12细胞经Lactacystin处理后,胞浆内可见明显的颗粒状、小团块状α-synuclein聚集体的生成;而经灵芝孢子多糖LPS3预处理后,胞浆中α-synuclein的聚集体明显减少。结论灵芝孢子多糖LPS3对Lactacystin诱导的PC12细胞损伤有一定的保护作用,其作用机制可能与抑制α-synuclein聚集体的生成有关。     

Orthogonal protein interactions in spore pigment producing and antibiotic producing polyketide synthases

The actinomycetes produce antibiotics as well as spore pigments during their life cycle by using Type II polyketide synthases (PKSs). Each PKS minimally consists of a ketosynthase heterodimer and an acyl carrier protein. The acyl carrier protein has been shown to be interchangeable among different antibiotic producing Type II PKSs. Surprisingly, we have discovered a fundamental incompatibility between the ketosynthases and acyl carrier proteins from antibiotic producing pathways and those from spore pigment pathways. Although antibiotic PKSs can interact with acyl carrier proteins from spore pigment pathways, spore pigment PKSs are unable to recognize acyl carrier proteins from polyketide antibiotic pathways. This observation provides an insight into a critical mechanism by which natural product biosynthetic specificity is exercised by members of this bacterial family.     

Efficacy of osthol,a potent coumarin compound,in controlling powdery mildew caused by Sphaerotheca fuliginea

The efficacy of osthol, a natural coumarin compound, in controlling powdery mildew was evaluated in 2004–2005 in Anhui and Hebei Provinces of China. In both years, the treatments (osthol 15.0 and 18.0 g ai ha^? 1) showed a stable control efficiency of 75.42, 81.24% and 76.36, 84.84%, respectively, at the Institutes of Plant Protection of Hebei Academy of Agricultural Sciences. In field experiments, osthol was as effective as difenoconazole in controlling powdery mildew and was more effective than triadimefon against Sphaerotheca fuliginea. Protection was expressed as a significant reduction (up to 87% compared with the control) in the mildewed leaf area in young pumpkin plants. Osthol strongly inhibited spore germination and mycelial growth of S. fuliginea in vitro, damaged the cell wall and the organelles of the pathogen. At 48 h after incubation, 50 μg ml^? 1 osthol could completely inhibit spore germination. These findings suggested that the effect of osthol on powdery mildew may be associated with the direct fungitoxic property against the pathogen. We conclude that osthol would be an attractive natural compound for practical agronomic use against powdery mildew.     

一株具有抗肿瘤活性的土壤放线菌的筛选与菌种鉴定

目的快速高效的筛选到有抗肿瘤活性的土壤放线菌。方法初筛采用MTT法检测样品作用后A549细胞、HGC-27细胞和正常对照细胞N9的成活率,PI染色流式细胞检测技术复筛可能致细胞凋亡的菌株,以及对活性菌株进行种属鉴定。结果与结论从350株土壤放线菌中初筛得到16株菌种,它们的代谢产物对A549及HGC-27细胞有抑制作用,但对N9细胞生长无影响;复筛得到1株编号为1070的菌株的代谢产物能使A549细胞经过处理后,经流式细胞仪检测到亚二倍体峰,峰高为32.07%。从菌株菌落形态、孢子丝形态、生理生化特性及16SrDNA序列、系统进化分析鉴定该菌种为Streptomyces capillispiralis。     

Chronic toxicity of cadmium in Pteris vittata,a roadside fern

The effect of Cd at concentrations of 0.1, 1.0, 2.5, 5.0 and 10.0 ppm on Pteris vittata, a commonly occurring roadside fern was studied during the entire life cycle from spore germination to spore production. Light, fluorescence, scanning and transmission electron microscopy were used to study the structural changes due to Cd. With increasing Cd concentrations the following changes were observed: inhibition of first and second generation spores, abnormal development of protonema, disintegration of thylakoid organization, delayed formation of reproductive elements and abnormal sporangia. As the Cd content of the plants increased with increasing concentration in the medium, biomass-specific concentrations of chlorophyll and carotenoids decreased. The gametophytic phase was more sensitive than the sporophytic stage to Cd. The differences noticed during the three stages of development could be useful as markers for Cd contamination in the environment.