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1.
Sweet home actinomycetes: The 1999 MDS Panlabs Lecture   总被引:1,自引:0,他引:1  
For the past 25 years, I have devoted most of my research efforts to the application of molecular genetics to yield improvement and production of novel secondary metabolites in actinomycetes. My group at Lilly Research Laboratories worked with a variety of Streptomyces species and with strains of Amycolatopsis and Saccharopolyspora. We developed molecular genetic tools to manipulate actinomycete genes, and applied them to important secondary metabolites, including tylosin, daptomycin, vancomycin, chloroeremomycin, and spinosyns. In the early years, I helped establish recombinant DNA technology to manufacture mammalian proteins, and more recently, helped implement microbial genomics as a research tool for antibiotic discovery. In this paper, I review some highlights, primarily from the actinomycete work. Journal of Industrial Microbiology & Biotechnology (2000) 24, 79–88. Received 25 October 1999/ Accepted in revised form 12 November 1999  相似文献   

2.
Abstract The relationship between antibiotic production and culture growth rate in Saccharopolyspora erythraea and Streptomyces hygroscopicus was manipulated by changing the growth-limiting substrate. Carbon- and nitrogen-limited cultures were studied and antibiotic synthesis was obtained in both cases in Saccharopolyspora erythraea cultures and in nitrogen-limited Streptomyces hygroscopicus cultures. In all cultures where antibiotic was detected, onset of antibiotic production coincided with the minimal protein synthesis rate. Further investigation in Saccharopolyspora erythraea cultures indicated that this corresponded to minimum ratio of charged to uncharged tRNA, i.e. when uncharged tRNA accumulated. This latter phenomenon was investigated in the presence of a protein synthesis inhibitor.  相似文献   

3.
AIMS: The objective of this work was to investigate the morphological and rheological properties in submerged culture of the three different basidiomycetes Phellinus (P. baumii, P. gilvus and P. linteus) that produce pharmacologically important exopolysaccharides (EPS). METHODS AND RESULTS: In flask cultures, pH proved to be a critical factor affecting mycelial growth, morphological change and EPS production. The macroscopic morphologies observed under different pHs in flask cultures were also comparable: i.e. starfish-like pellets with a lesser extent of free mycelium appeared in P. baumii, whereas smooth pellets with higher amounts of free mycelium were observed in P. gilvus and P. linteus. The pelleted fermentations were further characterized in a 5-l stirred-tank fermenter by image analysis with respect to mean diameter, core area and pellet circularity. Phellinus baumii showed the largest pellet size (5.2 mm in diameter), whereas P. linteus had extremely small and spherical pellets. The culture broth of P. baumii and P. gilvus yielded extremely high apparent viscosities, ranging from 5 to 7 Pa s. CONCLUSIONS: Three important species of Phellinus showed significantly different morphological and rheological properties. The morphological variation of the three Phellinus species was closely linked to EPS productivity and the apparent viscosity of the whole broth. SIGNIFICANCE AND IMPACT OF THE STUDY: The morphological change in the three species of Phellinus was a good indicator for identifying cell activity for EPS production. Our finding may be beneficial for further optimization of other fungal fermentation processes for large-scale production of EPS.  相似文献   

4.
糖多孢红霉菌A226 的原生质体转化和染色体同源整合   总被引:15,自引:0,他引:15  
糖多孢红霉菌的原生质体转化和染色体同源整合,是红霉素生物合成基因改造的重要途径。本研究对糖多孢红霉菌A226原生质体制备和转化条件进行了优化,结果表明以对数生长后期和稳定期菌丝体制备的原生质体转化效率较高;质粒、原生质体和PEG-T缓冲液体积比例为15:40:200(μl)时转化效果较好;比重小原生本的转化效率虽高,但在转化子中有效整合的比例较低;PEG1000和PEG3350对转化效率没有显差异;而Yamamoto转化系统优于Weber转化系统。PCR鉴定、抑菌活性鉴定和质谱分析均表明,转化质粒已整合到染色体红霉素合成基因位点。  相似文献   

5.
Summary A soil isolate ofStreptomyces roseosporus was found to produce spores in stirred submerged culture. Both biological mass and respiratory activity increased during the sporulation process. Contrary to other reports, the differentiation process was not purposefully initiated by critical manipulation of either nutritional or environmental conditions.  相似文献   

6.
Aims: To overproduce erythromycin C, B or D and evaluate the effect of disruption of tailoring genes eryK and eryG in an industrial erythromycin producer. Methods and Results: The tailoring genes eryG and eryK were inactivated individually or simultaneously by targeted gene disruption in an industrial strain Saccharopolyspora erythraea HL3168 E3, resulting in the overproduction of erythromycin C (2·48 g l?1), B (1·70 g l?1) or D (2·15 g l?1) in the mutant strain QL‐G, QL‐K or QL‐KG, respectively. Analysis of the erythromycin congeners throughout the fermentation indicated that, at the end of fermentation, comparatively large amount of erythromycin D (0·67 g l?1) was accumulated in QL‐G, whereas only small amount of erythromycin D (0·10 g l?1) was produced in QL‐K. Conclusions: Inactivation of tailoring genes eryG and eryK in the high producer did not affect the biosynthesis of erythromycin. However, erythromycin D could be more efficiently methylated by EryG than be hydroxylated by EryK. Significance and Impact of the Study: Development of the mutant strains provides a method for the economical large‐scale production of potent lead compounds. The information about the accumulation and conversion of erythromycins in the industrial strains may contribute to further improving erythromycin production.  相似文献   

7.
本文首次报导有关铜蒸气激光及其与氯化锂复合选育龟裂链霉菌的研究。在相同的实验条件下,铜蒸气激光辐照龟裂链霉菌比其随后又氯化锂复合处理的效果好。  相似文献   

8.
Abstract A linear plasmid was isolated from a strain of Streptomyces rimosus . This plasmid was separated by agarose gel electrophoresis and its size, about 43 kb, determined both by this method and by electron microscopy. The cleavage pattern of the linear plasmid with 5 restriction endonucleases is given. A protein, which is removed by proteinase K, is probably associated to this plasmid. By ethidium bromides or acridine orange treatment we obtained mutants which had lost their aerial mycelium and their linear plasmid.  相似文献   

9.
Abstract Streptomyces viridochromogenes was grown both as submerged and surface culture. Mycelia from these cultures were analysed for the composition of lipids and fatty acids. An increase in ornithinolipid content according to incubation time was observed. The addition of phosphate inhibited the ornithinolipid synthesis. A mutant strain with bald phenotype did not exhibit the phosphate inhibition. At the same time, the mutant strain had a higher content of 12-methyltetradecanoic acid.  相似文献   

10.
Many filamentous bacteria and fungi tend to form pellets, or mixtures of dispersed mycelium and pellets in liquid fermentation broths. In some cases, a specific kind of morphology is required for optimum product yield. When quantitative analysis and characterization of the pellet morphology are needed, an image processing system can be used. It allows a fast and reproducible analysis of the frequency distribution of pellet size, mean pellet size, contents of pellets, or their shape. The use of such a system allows for an on-line analysis. For a demonstration of the method, results of two fermentations of Streptomyces tendae are shown.  相似文献   

11.
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13.
Streptomyces lividans 1326 usually does not produce the red/blue colored polyketide actinorhodin in liquid culture even though it carries the entire actinorhodin biosynthesis gene cluster. The bacterium can be forced to produce this secondary metabolite by introducing actII-ORF4, the actinorhodin pathway-specific activator gene from Streptomyces coelicolor, on a multicopy plasmid. The production of actinorhodin by such a strain has been optimized by medium and process manipulations in fed-batch cultures. With high-yield cultivation conditions, 5 g actinorhodin/l are produced during 7 days of cultivation; or approximately 0.1 g actinorhodin/g dry weight (DW)/day in the production phase. The yield in this phase is 0.15 Cmol actinorhodin/Cmol glucose, which is in the range of 25% to 40% of the maximum theoretical yield. This high-level production mineral medium is phosphate limited. In contrast, nitrogen limitation resulted in low-level production of actinorhodin and high production of α-ketoglutaric acid. Ammonium as nitrogen source was superior to nitrate supporting an almost three times higher actinorhodin yield as well as a two times higher specific production rate. The wild-type strain lacking the multicopy plasmid did not produce actinorhodin when cultivated under any of these conditions. This work examines the actinorhodin-producing potential of the strain, as well as the necessity to improve the culture conditions to fully utilize this potential. The overexpression of biosynthetic pathway-specific activator genes seems to be a rational first step in the design of secondary metabolite overproducing strains prior to alteration of primary metabolic pathways for redirection of metabolic fluxes. Journal of Industrial Microbiology & Biotechnology (2002) 28, 103–111 DOI: 10.1038/sj/jim/7000219 Received 04 April 2001/ Accepted in revised form 30 October 2001  相似文献   

14.
目的:对采自海南、湛江等海域的海绵样品进行放线菌选择性分离,采用其发酵液进行抗肿瘤活性筛选,并对活性较好的菌株进行鉴定。方法:用含50μg/mL重铬酸钾为抑制剂的海水高氏一号合成培养基分离培养海绵放线菌;以MTT法进行菌株的抗肿瘤活性筛选;通过培养特征、形态特征、生理生化特征、16S rDNA序列测定及系统发育分析,对菌株HA01184进行鉴定。结果与结论:海水高氏一号合成培养基用于海绵放线菌分离培养具有很好的选择性,从海绵样品中共分离得到放线菌165株,细胞毒活性达80%以上的阳性菌株有10株,其中菌株HA01184的发酵液细胞毒活性为90%。结合形态观察、生理生化特征和16S rDNA序列比对分析,将HA01184归于链霉菌属,可能是来自海洋环境的一个潜在新种。  相似文献   

15.
AIMS: The objective of the present study was to determine the optimal culture conditions for mycelial biomass and exo-polysaccharide (EPS) by Cordyceps militaris C738 in submerged culture. METHODS AND RESULTS: The optimal temperatures for mycelial biomass and EPS production were 20 degrees C and 25 degrees C, respectively, and corresponding optimal initial pHs were found to be 9 and 6, respectively. The suggested medium composition for EPS production was as follows: 6% (w/v) sucrose, 1% (w/v) polypeptone, and 0.05% (w/v) K2HPO4. The influence of pH on the fermentation broth rheology, morphology and EPS production of C. militaris C738 was carried out in a 5-l stirred-tank fermenter. The morphological properties were comparatively characterized by pellet roughness and compactness by use of image analyser between the culture conditions with and without pH control. The roughness and compactness of the pellets indicated higher values at pH-stat culture (pH 6.0), suggesting that larger and more compact pellets were desirable for polysaccharide production (0.91 g g(-1) cell d(-1). CONCLUSIONS: Under the optimized culture conditions (with pH control at 6), the maximum concentration of biomass and EPS were 12.7 g l(-1) and 7.3 g l(-1), respectively, in a 5-l stirred-tank fermenter. SIGNIFICANCE AND IMPACT OF THE STUDY: The critical effect of pH on fungal morphology and rheology presented in this study can be widely applied to other mushroom fermentation processes.  相似文献   

16.
Two bifunctional plasmid vectors pZG5 (7.45 kb) and pZG6 (6.95 kb), for gene transfer between Streptomyces spp. and Escherichia coli have been constructed by fusion of the multicopy broad-host-range Streptomyces plasmid pIJ350 with E. coli plasmids Bluescribe M13- (pZG5) or pUC18 (pZG6). Both plasmids possess several unique restriction sites suitable for DNA cloning. Stable transformants of Streptomyces rimosus R6 and S. lividans 66 were obtained, harboring intact plasmids regardless of colony age or multiple subculturing. Moreover, pZG5 and pZG6 were successfully used to introduce several homologous transfer RNA genes into S. rimosus.  相似文献   

17.
用毛胶薯蓣提取分离毛胶薯蓣多糖胶(DSP)。将DSP与其他四种胶(瓜尔胶、魔芋胶、白芨胶、海藻酸钠)的粘度与浓度、温度、pH、降解时间、冻融变化及耐盐性的关系,以及起泡性能进行了比较研究。结果表明:DSP溶液的浓度与粘度正相关;温度在0~40℃间具有良好的热稳定性,40~90℃间其粘度随温度的升高而降低,且符合阿累尼乌斯动力学曲线;pH的改变、冻融变化和加入氯化钠、氯化钙对DSP粘度的影响甚微;同时DSP还具有优良的起泡性。  相似文献   

18.
Abstract Cell-free extracts of vegetative mycelia of Streptomyces aureofaciens and Streptomyces rimosus were found to reduce streptomycete-origin 8-hydroxy-5-deazaisoalloxazine derivatives (SF420) using NADPH as a dnor of hydrogen and electrons. 7,8-didemethyl-8-hydroxy-5-deazariboflavin (F0) also was a substrate, although with a lower reaction rate than that for SF420. NADH could not substitute for NADPH. The F420-reductase activity was also observed in homogenates of S. aureofaciens spores.  相似文献   

19.
Thermophilic actinomycetes were isolated from 163 (48.95%) of 333 samples of vegetable substrates and soil from different sites in Anambra and Enugu States in Nigeria.Thermoactinomyces (Tha.) vulgaris was the most common, occurring in 32.4% of samples whileTha. thalpophilus was isolated from 20.1%.Tha. sacchari, Saccharomonospora (Sam.) viridis andSaccharopolyspora (Sap.) rectivirgula were isolated from 3–10.5% of the samples examined.Streptomyces (Stm.) thermovulgaris occurred in 2.7% andThermomonospora spp. in 0.6% of samples. Except forStm. thermovulgaris and, perhaps,Thermomonospora spp., all the species isolated are known to be allergenic in man. The five known allergenic species were abundant in hay and maize silage.T. vulgaris andT. thalpophilus were also frequently isolated from rice straw.Tha. vulgaris, Tha. thalpophilus andSap. rectivirgula were all most numerous in hay whileTha. sacchari was most numerous in maize silage. The widespread occurrence of thermophilic actinomycetes in Nigeria emphasizes the need for investigation of their role in allergic respiratory disorders.  相似文献   

20.
This review article presents an outlook on the current strategies and existing concepts for culture surface designs to regulate cell morphologies and functions. First, cell structures and cell attachment behaviors are described in relation to the interactions between cells and their surroundings. Next, various surface designs are addressed, with a summary of the current topics of particular interest. The architectural features of substrates can be controlled to facilitate the quest for design principles including material choices and geometric modifications. In addition, various types of biomolecules, such as adhesive elements and growth factors, can be incorporated to regulate cell behaviors, including cell attachment, growth and differentiation. It is possible to manipulate these surface variables to produce desired surface designs for inducing cellular responses. In the latter part of this article, the topics discussed involve dendrimer-immobilized surfaces designed in authors' studies dealing with the in vitro culture processes of differentiated and undifferentiated cells. This article will offer novel insights into the processing of cells and tissues toward therapeutic applications in regenerative medicine.  相似文献   

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