Kofermentation heterologer Mikroorganismen als Quelle neuer Naturstoffe

In der Natur kommen Mikroorganismen stets als Gemeinschaft mehrerer Arten vor; in der biotechnologischen Praxis werden hingegen fast ausschließlich Reinkulturen taxonomisch definierter Mikroben eingesetzt. Im Rahmen der Dissertation wurde schließlich am Beispiel der Kombination aus dem Bildner der Roseoferine A - K, dem Mykoparasiten Mycogone rosea DSM 12973, und dem leucinostatinbildenden Endophyten Acremonium spec. Tbp-5 der Beweis für die Hypothese erbracht, daß in Kofermentation - auf Grund der wechselseitigen Interaktionen zwischen beiden Partnern - unter bestimmten Bedingungen ein anderes Sekundärmetabolitenmuster als in den jeweiligen Reinkulturen nachzuweisen ist. Die vorliegenden Untersuchungen lassen den Schluß zu, daß Kofermentationen in speziellen Fällen und unter Berücksichtigung entsprechender Ausgangsbedingungen einen geeigneten Weg darstellen, neue chemische Strukturen aufzufinden und das natürliche Produktspektrum eines mikrobiellen Produzenten zu diversifizieren: So konnten aus beiden Partnern insgesamt 28 strukturell neuartige Lipoaminopeptid-Antibiotika isoliert werden, von denen drei, die Acremostatine A, B und C, lediglich in den Kofermentationen nachgewiesen werden konnten

Harmonine, a defence compound from the harlequin ladybird, inhibits mycobacterial growth and demonstrates multi-stage antimalarial activity

The harlequin ladybird beetle Harmonia axyridis has been introduced in many countries as a biological control agent, but has become an invasive species threatening the biodiversity of native ladybirds. Its invasive success has been attributed to its vigorous resistance against diverse pathogens. This study demonstrates that harmonine ((17R,9Z)-1,17-diaminooctadec-9-ene), which is present in H. axyridis haemolymph, displays broad-spectrum antimicrobial activity that includes human pathogens. Antibacterial activity is most pronounced against fast-growing mycobacteria and Mycobacterium tuberculosis, and the growth of both chloroquine-sensitive and -resistant Plasmodium falciparum strains is inhibited. Harmonine displays gametocytocidal activity, and inhibits the exflagellation of microgametocytes and zygote formation. In an Anopheles stephensi mosquito feeding model, harmonine displays transmission-blocking activity

Front line defenders of the ecological niche! Screening the structural diversity of peptaibiotics from saprotrophic and fungicolous <i>Trichoderma/Hypocrea</i> species

Approximately 950 individual sequences of nonribosomally biosynthesised peptides are produced by the genus Trichoderma/Hypocreathat belong to a perpetually growing class of mostly linear antibiotic oligopeptides, which are rich in the non-proteinogenic α-aminoisobutyric acid (Aib). Thus, they are comprehensively named peptaibiotics. Notably, peptaibiotics represent ca. 80%of the total inventory of secondary metabolites currently known from Trichoderma/Hypocrea. Their unique membrane-modifying bioactivity results from amphipathicity and helicity, thus making them ideal candidates in assisting both colonisation and defence of the natural habitats by their fungal producers. Despite this, reports on the in vivo-detection of peptaibiotics have scarcely been published in the past. In order to evaluate the significance of peptaibiotic production for a broader range of potential producers, we screened nine specimensbelonging to seven hitherto uninvestigated fungicolous orsaprotrophic Trichoderma/Hypocrea species by liquid chromatographycoupled to electrospray high resolution mass spectrometry.Sequences of peptaibiotics found were independently confirmedby analysing the peptaibiome of pure agar culture

Ultracold neutron storage in a bottle coated with the fluoropolymer CYTOP

The fluoropolymer CYTOP was investigated in order to evaluate its suitability as a coating material for ultracold neutron (UCN) storage vessels. Using neutron reflectometry on CYTOP-coated silicon wafers, its neutron optical potential was measured to be 115.2(2) neV. UCN storage measurements were carried out in a 3.8 l CYTOP-coated aluminum bottle, in which the storage time constant was found to increase from 311(9) s at room temperature to 564(7) s slightly above 10 K. By combining experimental storage data with simulations of the UCN source, the neutron loss factor of CYTOP is estimated to decrease from 1.1(1)$$\times 10^{-4}$$ to 2.7(2)$$\times 10^{-5}$$ at these temperatures, respectively. These results are of particular importance to the next-generation superthermal UCN source SuperSUN, currently under construction at the Institut Laue-Langevin, for which CYTOP is a possible top-surface coating in the UCN production volume

Profiling of Arabidopsis Secondary Metabolites by Capillary Liquid Chromatography Coupled to Electrospray Ionization Quadrupole Time-of-Flight Mass Spectrometry

Large-scale metabolic profiling is expected to develop into an integral part of functional genomics and systems biology. The metabolome of a cell or an organism is chemically highly complex. Therefore, comprehensive biochemical phenotyping requires a multitude of analytical techniques. Here, we describe a profiling approach that combines separation by capillary liquid chromatography with the high resolution, high sensitivity, and high mass accuracy of quadrupole time-of-flight mass spectrometry. About 2,000 different mass signals can be detected in extracts of Arabidopsis roots and leaves. Many of these originate from Arabidopsis secondary metabolites. Detection based on retention times and exact masses is robust and reproducible. The dynamic range is sufficient for the quantification of metabolites. Assessment of the reproducibility of the analysis showed that biological variability exceeds technical variability. Tools were optimized or established for the automatic data deconvolution and data processing. Subtle differences between samples can be detected as tested with the chalcone synthase deficient tt4 mutant. The accuracy of time-of-flight mass analysis allows to calculate elemental compositions and to tentatively identify metabolites. In-source fragmentation and tandem mass spectrometry can be used to gain structural information. This approach has the potential to significantly contribute to establishing the metabolome of Arabidopsis and other model systems. The principles of separation and mass analysis of this technique, together with its sensitivity and resolving power, greatly expand the range of metabolic profiling