1,721,079 research outputs found
Charakterisierung von flockenbildenden und schnell sedimentierenden Mikroalgen-Bakterien-Konsortien in der Bioremediation
Get PDFThe microalgae-bacteria consortia (MBC) described here can be used for cost-efficient and continuous production of biomass in a chemostatic bioreactor. In order to obtain its characteristic sedimentation behavior, it is necessary to repeatedly select environmental samples for floc-forming and fast-sedimenting structures by gravitation. Comparative studies with unialgal cultures have been conducted, which have revealed exceptional sinking properties of the MBC. The predominant species was found to be dependent on the cultivation substrate while the sinking properties remained useful for bioreactor application. Furthermore, the manipulation of (a)biotic parameters demonstrated that floc aggregation can serve as a protective layer against extreme environmental conditions. It is known that extracellular polymeric substances (EPS) play a role in particle aggregation in marine snow and wastewater sludge. The flocculation process of the MBC was found to be driven by a biofilm matrix consisting mainly of proteins and polysaccharides. This was further demonstrated by an induced disaggregation with sonication and heat which resulted in rapid reflocculation unless subsequently inhibited by either an antibiotic or an enzymatic treatment. Moreover, the extracted EPS can function as a flocculant for the non-flocculating microalgae C. vulgaris. The sinking properties were significantly enhanced, which emphasized the importance of these substances in the floc-forming and sedimentation process. In conclusion, the investigations provided new insights into MBC and their potential in water treatment. As a next step, verifying the laboratory results in large-scale bioreactors can potentially facilitate the commercial biomass production.Die hier beschriebenen Mikroalgen-Bakterien Konsortien (MBC) können für eine kostengünstige und kontinuierliche Produktion von Biomasse in einem chemostatischen Bioreaktor verwendet werden. Um das charakteristische Sedimentationsverhalten zu erreichen, ist es erforderlich, natürliche Umweltproben wiederholt auf flockenbildende und schnell sedimentierende Strukturen zu selektieren. Es wurden vergleichende Studien mit unialgalen Kulturen durchgeführt, die außergewöhnliche Sinkfähigkeiten der MBC ergaben. Die vorherrschende Art variierte in Abhängigkeit vom Substrat, während die Sinkeigenschaften für die Bioreaktoranwendung erhalten blieben. Außerdem konnte durch die Manipulation von (a)biotischen Parametern gezeigt werden, dass die Flockenaggregation als Schutzschicht gegen extreme Umweltbedingungen dienen kann. Es ist bekannt, dass extrazelluläre polymere Substanzen (EPS) eine Rolle bei der Partikelaggregation im marine snow sowie in Klärschlamm spielen. Die Ergebnisse zeigen, dass der Flokkulationsprozess der MBC durch eine Biofilmmatrix gesteuert wird, die hauptsächlich aus Proteinen und Polysacchariden besteht. Eine durch Ultraschall und Hitze induzierte Disaggregation führte zu einer schnellen Reaggregation, sofern diese nicht durch eine nachfolgende antibiotische oder enzymatische Behandlung gehemmt wurde. Die extrahierten EPS konnten weiter als Flockungsmittel für die nicht-flokkulierende Mikroalge C. vulgaris fungieren und damit die Sinkeigenschaften verbessern, was die Bedeutung dieser Substanzen für den Flockenbildungs- und Sedimentationsprozess unterstreicht. Die Untersuchungen lieferten neue Einblicke in MBC und deren Wasserreinigungspotenzial. Eine Verifizierung der Laborergebnisse durch Untersuchungen in großtechnischen Bioreaktoren könnte in Zukunft die kommerzielle Biomasseproduktion erheblich erleichtern
Biotechnological Production of Carotenoids by Aquatic Microorganisms
Get PDFPopulation growth, higher expectations for a long and healthy life, and climate change are currently major drivers for the development and production of health-promoting, sustainable, and climate-friendly substances. A particular focus is on the food and pharmaceutical sectors, as these directly impact human health. This progress led to an increase in demand for additives improving the properties of food and feed. In this context, carotenoids play an important role. They comprise a group of natural pigments, which are used to color food and feed. The biotechnological production enables a sustainable supply of natural carotenoids, but there is still room for improvements in manufacturing processes. The aim of this work was to support the further development of the biotechnological production of carotenoids by optimizing methods and processes and by searching for new, promising production organisms: 1. The development of a method for the determination of astaxanthin from Haematococcus pluvialis helped to find a good compromise between simple and fast but also accurate measurement procedures. 2. The application of the developed method in the optimization of the downstream process of astaxanthin from H. pluvialis aimed to maximize astaxanthin yield while minimizing process costs and energy consumption. 3. The screening of a Thraustochytriaceae strain collection indicated that some strains are potentially suitable for a sustainable production of carotenoids. The gained comprehensive understanding is essential to improve the necessary production of carotenoids through optimized synthesis and processing, to enable targeted and economical use, and thus to make a lasting contribution to public health and climate protection
Ciona intestinalis in the spotlight of metabolomics and microbiomics: New insights into its invasiveness and the biotechnological potential of its associated microbiota
Get PDFThe tunicate Ciona intestinalis is one of the most notorious invasive ascidian species. In Prince Edward Island (PEI, Canada), C. intestinalis causes heavy fouling on farmed mussels leading to significant economic losses. Except for general beneficial eco-physiological characteristics of invasive ascidians, reasons underlying C. intestinalis’ invasiveness remain obscure. This study aimed to shed light on two additional factors potentially promoting its invasion success, i.e., bioactive secondary metabolites and associated microbiota, which reportedly contribute to the invasiveness of other marine species. Therefore, microbiomes and metabolomes of invasive (PEI) and native (Helgoland and Kiel, Germany) C. intestinalis populations were comparatively studied, a novelty in invasive ascidian research. Apart from being problematic invasive species, ascidians and their associated microbiota are a rich source for bioactive marine natural products (MNPs) relevant for human health. However, the biodiscovery potential of C. intestinalis-associated microorganisms remains largely unknown. Accordingly, this doctoral research project targeted to explore bioactivities and the chemical repertoire of culturable bacteria and fungi associated with C. intestinalis. Amplicon sequencing-based bacterial community analysis of gut, tunic, and seawater (control) samples revealed species-specificity and a diverse microbiota (39 phyla). The UPLC-MS/MS-based untargeted metabolomics approach revealed a diverse chemical inventory dominated by alkaloids and lipids. In addition to core bacteria and metabolites present in all samples, also tissue- and location-specific bacteria and metabolites were observed. Notably, highest microbial and chemical diversity were detected in the invasive C. intestinalis population (PEI). In combination, these results suggest a high adaptive capacity of C. intestinalis. In addition, several detected bacteria and secondary metabolites reportedly have antimicrobial, antifouling, and other relevant bioactivities, potentially promoting its overall health, fitness, and competitiveness. In conjunction with microbiome data, this first global metabolome study on C. intestinalis indicated microbial associates and chemical weapons as additional relevant factors promoting its invasion success. Therefore, this work contributes important basic knowledge for future projects scrutinizing the invasiveness of C. intestinalis. To investigate the potential of microorganisms associated with C. intestinalis in marine biodiscovery, isolates were obtained from tunics (T) and guts (G) due to their pivotal functions for the ascidian’s defense against, e.g., pathogens, and their reportedly different bacterial communities. In total, 89 (T) and 61 (G) bacteria as well as 22 (T) and 40 (G) fungi were isolated and identified from Helgoland and Kiel specimens. Many extracts showed antibacterial (T: 42%, G: 64%), antifungal (T: 10%, G: 11%), and/or anticancer (T: 6%, G: 22%) activities. A 2-step selection procedure considering bioactivity and metabolite profiles was applied to prioritize the most promising MNPs producers. This led to the selection of seven tunic- and nine gut-derived microbial extracts affiliated to the fungal group of ascomycetes (69%) and the bacterial taxa Actinobacteria (25%) and Bacillus sp. (6%). Through an UPLC-MS/MS-based dereplication workflow including molecular networking, in-silico approaches and manual database comparison, 170 compounds belonging to >40 different chemical families were putatively annotated, displaying a vast chemical diversity. Although this represents a significant increase in annotation rates compared to previous studies, still many compounds even from well-studied organisms (e.g., Penicillium and Streptomyces spp.) remained unknown. In summary, this study demonstrated a huge pharmaceutical potential of the culturable microbiota associated with C. intestinalis, including discovery of various putatively novel compounds. Application of novel selection and integrated dereplication procedures proved successful for strain prioritization and compound annotation. Furthermore, this strategy highlighted particularly fungi as so far uncharted and exceptionally promising resource for putatively novel anticancer and antimicrobial lead compounds of high interest
Inducing the Chemodiversity of Fucus vesiculosus-Derived Fungi by OSMAC Strategy for Discovery of New Anticancer Leads
Get PDFAlgae-derived (algicolous) fungi has been regarded as an important source for discovery of novel bioactive natural products. As one of the most-widespread brown algae that occur in the shallow coastal regions of Baltic Sea, Fucus vesiculosus provides habitat for many invertebrates and vertebrates. However, the fungal community associated with F. vesiculosus has not been investigated for their chemical constituents or bioactivity potential. This Ph.D. project aimed to pursue a culture-based approach to isolate fungi from F. vesiculosus for discovery of new anticancer lead compounds. In order to induce the chemical space of fungi associated with Fucus vesiculosus, an OSMAC approach that included variations in media composition and culture regimes (liquid/solid) was applied. The crude extracts of ten fungal isolates showed anticancer bioactivities against at least one cancer cell line under one culture condition. MS/MS-based molecular networking (MN) combined with bioactivity mapping was applied to those crude extracts, allowing the identification and prioritization of two endophytic fungal strain, Pyrenochaetopsis sp. FVE-001 and FVE-087 with anticancer activity. Both strains were selected for large-scale fermentation followed by massive metabolomics analysis and chemical work-up.
For Pyrenochaetopsis sp. FVE-001, a modified Kupchan partition method was applied to crude extract to separate the crude extract into three subextracts. Bioactivity was tracked to the chloroform subextract, which was fractionated on a C18 solid-phase extraction (SPE) cartridge. The anticancer activity was mapped onto molecular networks (the so-called bioactivity-based MN), and with the aid of additional bioinformatics application, the anticancer activity of the compounds in the network was predicted. The compound isolation was carried out in a targeted manner from the bioactive fractions to yield three new decalinoylspirotetramic acid derivatives, pyrenosetins A-C, and a known decalin derivative, phomasetin. As expected, pyrenosetins A and B showed strong inhibitory potential against malignant melanoma cell A-375 with IC50 values of 2.8 and 6.3 μM, respectively.
The bioactivity-guided isolation of the second Pyrenochaetopsis sp. FVE-087 strain yielded one new decalinoyltetramic acid derivative, pyrenosetin D, and two known compounds wakodecalines A and B. Pyrenosetin D possesses an unusual pentacyclic ring system, which is rare in nature. Bioassay results showed that pyrenosetins D exhibited moderate anticancer bioactivity against A-375 with IC50 value of 77.5 μM, while wakodecalines A and B were inactive.
The current study represents a successful application of OSMAC in inducing new compounds with anticancer activity in algicolous fungi. Further combination of MN and additional information layers such as bioactivity data has successfully led to rapid purification of new compounds pyrenosetins A-D from two Fucus vesiculosus-derived Pyrenochaetopsis sp. strains. This is the first study focusing on secondary metabolites of algal-derived Pyrenochaetopsis sp
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Meer Kosmetik. Neue Rohstoffe und Kosmetikkonzepte aus dem Meer – was können marine mikrobielle Ressourcen dazu beitragen?
No full textEin ungewöhnlicher Stärkeabbauweg im hyperthermophilen archaeellen Sulfatreduzierer Archaeoglobus fulgidus Stamm 7324 und Charakterisierung Stärke-abbauender Enzyme aus geothermalen Habitaten
Get PDFComparative analyses of sugar catabolism in archaea revealed that degradation of glucose and hexose polymers proceeds via modified glycolytic pathways, mainly via modified Embden-Meyerhof pathways. The utilization of sugars by Archaeoglobus fulgidus species, which represent the first isolated archaeal sulfat reducer, has not unequivocally been demonstrated so far. Thus, in this thesis it was found that Archaeoglobus fulgidus strain 7324, rather than the type strain VC16, was able to grow on starch and sulfate as energy and carbon source. Starch was degraded to acetate via an unusual starch degradation pathway. Some key enzymes were purified and characterized. Furthermore, starch degrading and modifying enzymes from geothermal habitats were characterized to find properties useful for biotechnological applications. 2.1 Starch degradation in A. fulgidus strain 7324 A. fulgidus strain 7324 was found to grow on starch (1 g/l) and sulfate (30 mM) in presence of yeast extract (0.5 g/l) as energy and carbon source. During exponential growth on starch, 1 mol of glucose-equivalent was incompletely oxidized with sulfate to approximately 2 mol acetate, 2 mol CO2 and 1 mol H2S. Beside starch, amylose and β-cyclodextrin were used as substrates. Other sugars, e.g. glucose, fructose and maltose were not utilized. This is the first report of growth of a sulfate reducer on starch, i.e. on a polymeric sugar. Extracts of starch-grown cells of A. fulgidus Stamm 7324 contained all activites of an unusual starch degradation pathway to acetate, which includes the conversion of starch to glucose 6-phosphate as well as the conversion of glucose to pyruvate via a modified Embden-Meyerhof pathway. Specific activities of the key enzymes of the starch conversion to acetate were significantly higher in starch-grown cells than in lactate-grown cells, indicating induction of these enzymes during starch catabolism. In A. fulgidus strain VC16 neither enzyme activities of starch degradation nor the corresponding homologous genes were detected. Starch degradation to glucose 6-phosphate. Extracts of starch-grown A. fulgidus strain 7324 contained all enzymes of a starch degradation pathway so far only described for Klebsiella oxytoca and Thermococcus sp. B1001. In this pathway starch is converted to cyclodextrins by means of a cyclodextrin glucanotransferase. After transport into the cell cyclodextrins are linearised via a cyclodextrinase. By means of a maltodextrin phosphorylase the resulting maltooligodextrins are cleaved by phosporylation. The resulting glucose 1-phosphat is converted via phosphoglucomutase to glucose 6-phosphat, an intermediate of glycolysis. These four enzymes were purified and characterized. The N-terminal amino acid sequences and the molecular and catalytic properties of the enzymes were very similar to their homologs of the Thermococcales. The classical enzymes of starch degradation, α-amylase and pullulanase, could not be detected in A. fulgidus strain 7324 Glucose degradation to pyruvate via a modified Embden-Meyerhof pathway. In extracts of starch-grown cells the following enzymes of a modified Embden-Meyerhof pathway were detected: ADP-dependent glucokinase, phosphoglucose isomerase, ADP-dependent 6-phosphofructokinase, fructose-1,6-phosphate aldolase, glyceraldehyde-3-phosphate: ferredoxin oxidoreductase, phosphoglycerate mutase, enolase, and pyruvate kinase. So far, this pathway was only described for Thermococcales. The first enzyme of this modified Embden-Meyerhof pathway, ADP-dependent glucokinase, was purified and characterized. The properties of the glucokinase were similar to the glucokinases from Thermococcales. So far, formation of glucose as substrate of the ADP-dependent glucokinase can not be explained by the described starch degradation pathway. Pyruvate conversion to acetate. Pyruvate conversion to acetate involved pyruvate: ferredoxin oxidoreductase and ADP-forming acetyl-CoA synthetase. Activities of phosphotransacetylase and acetate kinase could not be detected. The findings indicate that the archaeal sulfate reducer A. fulgidus strain 7324 converts starch to acetate via an unsual starch degradation pathway, a modified Embden-Meyerhof pathway and acetyl-CoA synthetase (ADP-forming). This is the first report of a starch degradation pathway in a sulfate reducer. 2.2 Characterization of starch degrading enzymes from geothermal habitats Furthermore, starch degrading and modifying enzymes from geothermal habitats were characterized within the EC project �Thermogenes�. The genes of these enzymes were isolated from environmental DNA and organisms, respectively, originating from geothermal habitats in Iceland. The intention of these experiments was the characterization of enzymes from the glycosylhydrolase family 13 in respect to their substrate specificity, cation dependence and stability in order to find properties of biotechnological interest. Starting from seven different isolated, sequenced and cloned. Seven different genes of starch degrading enzymes were expressed in E. coli, purified and characterized. One protein showed pullulanase activity and one neopullulanase activity, respectively; five proteins exhibited cyclodextrinase activity. The characterized proteins were highly stable at moderate thermophilic conditions and showed a broad substrate spectrum, useful properties for biotechnological applications. Differences in substrate specificity can be explained by differences in amino acid sequences, e.g. the existence of a N-terminal domain correlated with cyclodextrinase activity
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