Neue Einblicke in den Gärungsstoffwechsel von Clostridium acetobutylicum

Clostridium acetobutylicum ist ein lösungsmittelbildendes Bakterium, vor allem das produzierte Butanol macht den Organismus industriell interessant, da es als „Biokraftstoff“ nutzbar ist. Unter diesem Aspekt war das Ziel in dieser Arbeit die Steigerung der Butanolkonzentration sowie die Reduktion von Nebenprodukten. Um das Bakterium durch genetische Manipulation, auch als „Metabolic Engineering“ bezeichnet, zu verändern und sukzessive einzelne Stoffwechselzweige auszuschalten, wurde das ClosTron®-System verwendet

Human Coronavirus NL63 Open Reading Frame 3 encodes a virion-incorporated N-glycosylated membrane protein

Background: Human pathogenic coronavirus NL63 (hCoV-NL63) is a group 1 (alpha) coronavirus commonly associated with respiratory tract infections. In addition to known non-structural and structural proteins all coronaviruses have one or more accessory proteins whose functions are mostly unknown. Our study focuses on hCoV-NL63 open reading frame 3 (ORF 3) which is a highly conserved accessory protein among coronaviruses. Results: In-silico analysis of the 225 amino acid sequence of hCoV-NL63 ORF 3 predicted a triple membranespanning protein. Expression in infected CaCo-2 and LLC-MK2 cells was confirmed by immunofluorescence and Western blot analysis. The protein was detected within the endoplasmatic reticulum/Golgi intermediate compartment (ERGIC) where coronavirus assembly and budding takes place. Subcellular localization studies using recombinant ORF 3 protein transfected in Huh-7 cells revealed occurrence in ERGIC, Golgi- and lysosomal compartments. By fluorescence microscopy of differently tagged envelope (E), membrane (M) and nucleocapsid (N) proteins it was shown that ORF 3 protein colocalizes extensively with E and M within the ERGIC. Using N-terminally FLAG-tagged ORF 3 protein and an antiserum specific to the C-terminus we verified the proposed topology of an extracellular N-terminus and a cytosolic C-terminus. By in-vitro translation analysis and subsequent endoglycosidase H digestion we showed that ORF 3 protein is N-glycosylated at the N-terminus. Analysis of purified viral particles revealed that ORF 3 protein is incorporated into virions and is therefore an additional structural protein. Conclusions: This study is the first extensive expression analysis of a group 1 hCoV-ORF 3 protein. We give evidence that ORF 3 protein is a structural N-glycosylated and virion-incorporated protein.Web of Scienc

Amino acid and amino sugar compositional changes during in vitro degradation of algal organic matter indicate rapid bacterial re-synthesis

Amino acids (AA) and, more recently, amino sugars (AS) in marine or lacustrine sediments have been increasingly used as paleoproxies. In order to assess AA and AS compositional changes during simulated microbial degradation, as well as to understand the importance of amino-compound re-synthesis by microbes during early diagenesis, decomposition experiments (300  days) were performed with algal (Fragilaria crotonensis) organic matter (OM)/quartz-sand mixtures under controlled redox conditions. Despite expected greater overall degradability under oxic conditions, decomposition kinetics of the bulk algal OM, as well as the total particulate AA and AS were similar under oxic and anoxic conditions, following exponential decay kinetics consistent with the observed mobilization and transfer of large parts of the particulate organic carbon (C) and nitrogen (N) into the dissolved inorganic and organic C and N pools. Carbon-normalized AA and AS yields suggest relative enrichment of amino compounds during partial decomposition, indicating the production and accumulation of microbial biomass during early diagenesis, independent of the redox environment. Moreover, AA and AS compositional changes, such as the relative enrichment of the AA glycine and the AS muramic acid (MurA), and the decrease in the molar ratio of glucosamine and galactosamine (GlcN:GalN) during degradation in both redox systems, were consistent with significant bacterial re-synthesis and the preferential preservation of bacterial biomaterial with increasing diagenesis. Large disparities between different bacterial amino-sugar based estimates of bacterial contribution indicate that bacterial end-member compositions are not currently known well enough to make these bacterial-biomarker constraints quantitative. However, the overall trends are consistent, indicating substantial turnover of eukaryotic into bacterial OM on short time scales of weeks to months. Together these results suggest that the influence of bacterial reworking in conserving sedimentary OM via its transfer into more refractory OM pools may be substantially greater than previously appreciated. We also investigated established amino-compound based indicators of OM degradation, bacterial synthesis, and sediment reactivity. Despite discrepancies, which we attribute to different susceptibilities of the respective indicators towards degradational changes on different time-scales, the tested indices were overall consistent with past data. These results therefore confirm their value as universal indicators of OM diagenesis. Together, our data highlight the vital role of bacterial reworking on the composition of sedimentary OM, with important implications for the alteration of primary geochemical signatures during early sedimentary diagenesis and their use as proxies in paleoenvironmental studies.ISSN:0016-7037ISSN:1872-953

Die Zukunft der Energiewende in Deutschland

Ungeachtet der weithin geteilten Ziele einer Energiewende in Deutschland sind doch die konkreten Wege dorthin heftig umstritten. Die Einzelmaßnahmen der Energiewendepolitik und ihr Zusammenspiel sowie die Einbettung in den europäischen Kontext sind Gegenstand kontroverser wissenschaftlicher und öffentlicher Debatten. Insbesondere bei der Förderung erneuerbarer Energien werden vor dem Hintergrund vielfältiger Kritik in Kürze die Weichen für die Zukunft neu gestellt. Eine stimmige Weiterentwicklung der Energiewendepolitik und eine sachgerechte Begleitung durch eine kritische Öffentlichkeit setzen voraus, dass die langfristigen Auswirkungen politischer Entscheidungen in einem komplexen sozio-technischen Energiesystem berücksichtigt werden. Auf Kurzfristeffekte oder ausschnitthafte Problemwahrnehmungen abzielende Politikansätze oder Politikempfehlungen werden dem jedoch nicht gerecht

The future of the energy transition in Germany

Although the goals of the country’s energy transition (Energiewende) are widely accepted in Germany, the specific route to get there is itself a matter of great controversy. The individual measures that are part of the energy transition policy and the questions of how they interact and how they are embedded in the European context are objects of controversial scientific and public debate. Most recently, the consequences for the price of electricity have, in particular, been discussed intensely. Against this backdrop of wide-ranging criticism, the future course for promoting renewable energy will soon be set. The German Renewable Energy Sources Act (the Erneuerbare-Energien-Gesetz, EEG), which is the main instrument of energy transition policy with its feed-in tariffs, is supposed to be fundamentally revised in the course of this year. A precondition for achieving a coherent further development of the energy transition policy and for receiving the sound support of a critical public is that the long-term consequences of political decisions on a complex sociotechnical energy system be taken into account. The requirements of such a system are not satisfied by policy approaches or recommendations that target short-term effects or that are perceptions of problems extrapolated from individual sectors. On the basis of its integrated research on the energy transition, researchers from the Helmholtz Alliance Energy-Trans take a stand on current important controversial issues from the energy transformation and specify fundamental challenges to shaping a sustainable energy transition policy