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Item type:Publication, Access status: with files , Einfluss von Hochdruck auf die Synthese von N-Acetylneuraminsäure in einem FestbettreaktorThe continuous application of high pressure in biotechnology was shown for the production of Neu5Ac starting from GlcNac and Pyr. Two immobilized enzymes were used. For the investigation of the reaction kinetic a fixed bed reactor and for the position of equilibrium a circular reactor was used. By using up to 1,300 bar the equilibrium was positively influenced by pressure. Pressure caused an increase in affinity for some reactants towards the enzymes. The high-pressure circular reactor in particular showed great potential due to two different pressure regimes (high pressure and ambient pressure) enabling an easy taking of samples while the reaction is at high pressure.Publicationtype: Doctoral Thesis56 49 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , High-pressure reactor technology for aerated biotransformationsUtilizing pressure as a process parameter can make biotechnological processes more efficient and attractive compared to established ones. This paper presents a high-pressure reactor setup for enzymatically catalyzed gas–liquid reactions, which can be operated up to 15.0 MPa. The reactor is equipped with optical measurement technology for inline and in situ monitoring of the oxygen concentration under high-pressure conditions. The setup is characterized by assessing the influence of the process parameter pressure on the conversion of the glucose oxidation to d-glucono-δ-lactone by immobilized glucose oxidase. The study demonstrates that the increased oxygen availability due to higher solubility reduces the reaction time in a batch reactor from 270 to 90 min.Publicationtype: Journal Article65 14 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Shift of the reaction equilibrium at high pressure in the continuous synthesis of neuraminic acid(Beilstein-Institut zur Förderung der Chemischen Wissenschaften, 2022-05-20); ; ; ; The importance of a compound that helps fight against influenza is, in times of a pandemic, self-evident. In order to produce these compounds in vast quantities, many researchers consider continuous flow reactors in chemical industry as next stepping stone for large scale production. For these reasons, the synthesis of N-acetylneuraminic acid (Neu5Ac) in a continuous fixed-bed reactor by an immobilized epimerase and aldolase was investigated in detail. The immobilized enzymes showed high stability, with half-life times > 173 days under storage conditions (6 °C in buffer) and reusability over 50 recycling steps, and were characterized regarding the reaction kinetics (initial rate) and scalability (different lab scales) in a batch reactor. The reaction kinetics were studied in a continuous flow reactor. A high-pressure circular reactor (up to 130 MPa) was applied for the investigation of changes in the position of the reaction equilibrium. By this, equilibrium conversion, selectivity, and yield were increased from 57.9% to 63.9%, 81.9% to 84.7%, and 47.5% to 54.1%, respectively. This indicates a reduction in molar volume from N-acetyl-D-glucosamine (GlcNAc) and pyruvate (Pyr) to Neu5Ac. In particular, the circular reactor showed great potential to study reactions at high pressure while allowing for easy sampling. Additionally, an increase in affinity of pyruvate towards both tested enzymes was observed when high pressure was applied, as evidenced by a decrease of KI for the epimerase and KM for the aldolase from 108 to 42 mM and 91 to 37 mM, respectively.Publicationtype: Journal ArticleScopus© Citations 2 54 236 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Enhanced sequestration of carbon dioxide into calcium carbonate using pressure and a carbonic anhydrase from alkaliphilic Coleofasciculus chthonoplastesCO2 in the atmosphere is a major contributor to global warming but at the same time it has the potential to be a carbon source for advanced biomanufacturing. To utilize CO2, carbonic anhydrase has been identified as a key enzyme. Furthermore, attempts have been made to accelerate the sequestration via pressure. This study aims to combine both approaches to achieve high sequestration rates. The carbonic anhydrase of the alkaliphilic cyanobacterium Coleofasciculus chthonoplastes (cahB1) and bovine carbonic anhydrase (BCA) are introduced into a high-pressure reactor to catalyze the hydration of CO2 at up to 20 bar. The reactor is filled with a CaCl2 solution. Due to the presence of Ca2+, the hydrated CO2 precipitates as CaCO3. The impact of the carbonic anhydrase is clearly visible at all pressures tested. At ambient pressure a CO2 sequestration rate of 243.68 kgCaCO3/m3 h for cahB1 was achieved compared to 150.41 kgCaCO3/m3 h without enzymes. At 20 bar the rates were 2682.88 and 2267.88 kgCaCO3/m3 h, respectively. The study shows the benefit of a combined CO2 sequestration process. To examinate the influence of the enzymes on the product formation, the precipitated CaCO3 was analyzed regarding the crystalline phase and morphology. An interchange of the crystalline phase from vaterite to calcite was observed and discussed.Publicationtype: Journal ArticleScopus© Citations 6 106 423