A novel antibiotic produced by <Emphasis Type="Italic">streptomyces noursei</Emphasis> Da07210

A novel antibiotic 210-A, named as (6S,8aS,9S,11S,12aR)-6-hydroxy-9,10-dimethyldecahydrobenzo[d]azecine-2,4,12(3H)-trione, was isolated from the fermentation broth of Streptomyces noursei Da07210, its structure was unambiguously established by spectral analyses and chemical comparison with related cycloheximide. Experiments demonstrated that 210-A bore strong activity against Fusarium oxysporum f. sp. cubense race four (Foc race four), which also showed antitumor activity against SMMC-7721 human hepatocarcinoma cells and S180 murine sarcoma, and the IC₅₀ values were 0.77 and 0.74 μg/ml, respectively.     

三江源地区不同退化程度草地的土壤放线菌区系

用不同分离方法,对三江源地区不同退化程度草地土壤放线菌的数量和多样性进行了比较.从5份土样中共分离放线茵178株,根据表型特征和16S rRNA基因序列分析,分别归入7个已知属:小单孢菌属(Micromonospora)、原小单孢菌属(Promicromonospora)、诺卡氏菌属(Nocardia)、假诺卡氏菌属(Pseudonocardia)、游动放线菌属(Actinoplanes)、韩国生工茵属(Kribbella)和链霉菌属(Streptomyces).其中链霉菌属分离菌株可归入7个表型类群.发现轻度退化高寒草原的土壤放线菌数量,丰度和多样性高于重度退化高寒草原;针茅高寒草原的土壤放线菌数量和多样性高于蒿草高寒草甸,而其中链霉菌的种类低于后者.表明高寒草地的退化程度与其中土壤放线茵的数量和多样性呈负相关.     

云南土壤放线菌生态分布的研究

云南具有极为复杂的地理气候。根据云南省不同的地质、地理、土壤、气候、植被特点选择样区,采集土壤样品,研究了云南不同地区、不同生态环境放线菌的生态分布与植被的关系。将云南土壤放线菌区系划分为热带区系、亚热带高原区系、滇西北高山区系和雪山区系四种类型。对云南土壤放线菌区系的特点进行了讨论。     

Evaluation of Streptomyces sp. strain g10 for suppression of Fusarium wilt and rhizosphere colonization in pot-grown banana plantlets

Streptomyces sp. strain g10 exhibited strong antagonism towards Fusarium oxysporum f.sp. cubense (Foc) races 1, 2 and 4 in plate assays by producing extracellular antifungal metabolites. Treating the planting hole and roots of 4-week-old tissue-culture-derived Novaria banana plantlets with strain g10 suspension (10⁸ cfu/ml), significantly (P<0.05) reduced wilt severity when the plantlets were inoculated with 10⁴ spores/ml Foc race 4. The final disease severity index for leaf symptom (LSI) and rhizome discoloration (RDI) was reduced about 47 and 53%, respectively, in strain g10-treated plantlets compared to untreated plantlets. Reduction in disease incidence was not significant (P<0.05) when plantlets were inoculated with a higher concentration (10⁶ spores/ml) of Foc race 4. Rhizosphere population of strain g10 showed significant (P=0.05) increase of more than 2-fold at the end of the 3rd week compared to the 2nd week after soil amendment with the antagonist. Although the level dropped, the rhizosphere population at the end of the 6th week was still nearly 2-fold higher than the level detected after 2 weeks. In contrast, the root-free population declined significantly (P=0.05), nearly 4-fold after 6 weeks when compared to the level detected after 2 weeks. Neither growth-inhibiting nor growth-stimulating effects were observed in plantlets grown in strain g10-amended soil.     

Development of a 16S rRNA gene-based prototype microarray for the detection of selected actinomycetes genera

Actinomycetes are known for their secondary metabolites, which have been successfully used as drugs in human and veterinary medicines. However, information on the distribution of this group of Gram-positive bacteria in diverse ecosystems and a comprehension of their activities in ecosystem processes are still scarce. We have developed a 16S rRNA-based taxonomic microarray that targets key actinomycetes at the genus level. In total, 113 actinomycete 16S rRNA probes, corresponding to 55 of the 202 described genera, were designed. The microarray accuracy was evaluated by comparing signal intensities with probe/target-weighted mismatch values and the Gibbs energy of the probe/target duplex formation by hybridizing 17 non-actinomycete and 29 actinomycete strains/clones with the probe set. The validation proved that the probe set was specific, with only 1.3% of false results. The incomplete coverage of actinomycetes by a genus-specific probe was caused by the limited number of 16S rRNA gene sequences in databases or insufficient 16S rRNA gene polymorphism. The microarray enabled discrimination between actinomycete communities from three forest soil samples collected at one site. Cloning and sequencing of 16S rRNA genes from one of the soil samples confirmed the microarray results. We propose that this newly constructed microarray will be a valuable tool for genus-level comparisons of actinomycete communities in various ecological conditions.     

星形孢菌素的发酵条件优化

提高抗生素在产生菌中的表达效价,从而降低生产成本,是实现抗生素生产应用的重要基础.星形孢菌素是一种非特异性的蛋白激酶抑制剂,能够诱导多种类型的细胞凋亡,但目前星形孢菌素生产菌株的表达效价均较低,达不到生产要求,使其应用受到限制[1-4].     

Ultrastructure of infected cells in the actinorhizal root nodules ofGymnostoma papuanum (Casuarinaceae) prepared by high pressure freezing and chemical fixation

Summary Actinorhizal root nodules ofGymnostoma papuanuum (Casuarinaceae) were examined with transmission electron microscopy after being either fixed with glutalaldehyde and osmium tetroxide or frozen with liquid nitrogen at high pressure and freeze-substituted. Much better preservation was obtained by the cryopreservation method. Mitochondria, plastids, membranes und ribosomes were much better preserved in the frozen specimens than in the chemically fixed tissues. No nucleoids were observed in the microsymbiont in frozen specimens. In contrast nucleoid regions were present in chemically fixed specimens. The actinomycete microsymbiont differentiates small spherical-shaped symbiotic vesicles after the hyphae have grown and penetrated into most regions of the cytoplasm.Dedicated to the memory of Professor Oswald Kiermayer     

Actinomycetous root nodules in angiosperms of Pakistan

Summary In a survey, out of the nineteen genera of non-leguminous angiosperms that are already reported to bear actinomycete-induced nitrogen-fixing root nodules from various parts of the world, the species of seven genera (Alnus, Elaeagnus, Hippophaë, Coriaria, Datisca, Rubus and Casuarina) have been located in Pakistan and checked for nodulation. All the investigated species of the these genera, except those of Rubus and some of the introduced species of Casuarina, were found to bear nodules. In all 12 species belonging to six genera of five families have been recorded to bear actinorhizal nodules in Pakistan.     

Inhibition of cellular phosphatidylinosito, turnover by psi-tectorigenin

Psi-tectorigenin, an isoflavonoid, was isolated from a culture filtrate of actinomycetes as an inhibitor of epidermal growth factor-induced phosphatidylinositol turnover in cultured A431 cells. It inhibited phosphatidylinositol turnover with an IC₅₀ of about 1 μg/ml; thus, its inhibitory activity was 6-times stronger than that of genistein or orobol. When added to cultured A431 cells psi-tectorigenin inhibited phosphatidylinositol turnover without inhibiting epidermal growth factor receptor tyrosine protein kinase. Thus, psi-tectorigenin is a specific inhibitor of phosphatidylinositol turnover and may be a useful tool for the functional analysis of phosphatidylinositol turnover.