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The product formation of the biopellets of filamentous fungi, such as Aspergillus niger, is closely linked with the pellet morphology. Therefore, investigations were carried out to determine the influence of fluid dynamic conditions on the growth of fungal pellets. During the present study, important information about the evolution of morphological changes during the cultivation process in stirred tank reactors was gathered from cultivations at different volumetric power inputs by agitation and aeration. The quantification of the pellet morphology was accomplished by the digital image analysis and the laser diffraction technique tracing parameters like the pellet diameter and the pellet concentration. The property of the pellet surface structure was determined by the microscopic image analysis of the pellet slices and verified by sedimentation velocity measurements. Results revealed a notable variation in morphological data among pellets cultivated at different volumetric power inputs by agitation and aeration, by which the production yields of the model product glucoamylase were correspondingly altered. Furthermore, without raising the total energy input, by utilizing of the different impact of aeration- and agitation-induced volumetric power input on the fungal pellet morphology, the product formation could be consequentially improved. Die Produktbildung der Biopellets von filamentösen Pilzen, wie Aspergillus niger, ist eng mit der Pelletmorphologie verknüpft. Daher wurden Untersuchungen durchgeführt, um den Einfluss von fluiddynamischen Bedingungen auf das Wachstum von Pilzpellets zu bestimmen. In der vorliegenden Arbeit wurden wichtige Informationen über die Entwicklung der morphologischen Veränderungen von Kultivierungen bei verschiedenen Leistungseinträgen durch Rühren und Begasen gesammelt. Die Quantifizierung der Pelletmorphologie wurde, zur Erfassung verschiedener Parameter wie zum Beispiel des Pelletdurchmessers oder der Pelletkonzentration, mit Hilfe von Bildanalyse und Laserbeugung durchgeführt. Die Qualifizierung der Pelletoberflächenstruktur wurde durch die mikroskopische Bildanalyse von Pelletschnitten bestimmt und durch Sinkgeschwindigkeitsmessungen verifiziert. Die Ergebnisse zeigten eine bemerkenswerte Variation in morphologischen Daten bei Pellets, die unter verschiedenen Leistungseinträgen durch Rühren und Begasen kultiviert wurden, wodurch sich die Ausbeuten des Modellprodukts Glucoamylase entsprechend veränderten. Weiterhin konnte ohne Erhöhung des Gesamtenergieeintrags bei Variation des begasungs- und rührerinduzierten Leistungseintrags die Pelletmorphologie verändert und die Produktbildung verbessert werden.
Das Ziel der Arbeit bestand darin, die lokalen und globalen mechanischen Beanspruchungsparameter in einem Rührkesselbioreaktor mit Hilfe der numerischen Strömungssimulation (CFD) nachzubilden und die Ergebnisse mit experimentellen Daten der Pellet-kultivierung bzgl. Fluiddynamik und Rheolgie des rekombinanten Stammes A. niger SKAn1015 zu validieren. Ausgehend von der einphasigen Strömungssimulation eines 2L-Bioreaktors werden zunächst Simultionsdaten über Strömungsgeschwindigkeit und mechanische Beanspruchung diskutiert. Aßerdem erfolgt eine Validierung der einphasigen Simulationsdaten mit der Particle Image Velocimetry. In weiteren Untersuchungen wird die Strömungssimulation auch auf nicht-newtonsche Flüssigkeiten, so wie sie bei der Kultivierung filamentöser Pilze üblicherweise auftreten, mit dem Ostwald - de Waele-Ansatz erweitert und die mechanische Beanspruchung in Abhängigkeit zu den rheologischen Prozessparametern korreliert. Die Untersuchung des Einflusses unterschiedlicher Rührergeometrien auf die Strömungsfelder und die mechanische Beanspruchung mittels CFD bildet den Abschluss, so dass die Auswahl eines geeigneten Rührers für den Kultivierungsprozess mit schesensitiven biologischen Systemen eindeutig getroffen wird. Die Arbeit validiert die numerische Strömungssimulation in einem Bioreaktor mit experimentell gnerierten biologischen und fluiddynamischen Prozessdaten und gibt praktische Hinweise darüber, wie biotechnologische Prozesse mit filamentösen Mikroorganismen hinsichtlich der Minimierung der mechanischen Beanspruchung zu betreiben sind.
The filamentous actinomycete Actinomadura namibiensis is the only known producer of labyrinthopeptins, a class of ribosomally synthesized and posttranslationally modified peptides (RiPPs) displaying highly attractive bioactive properties. In order to increase the labyrinthopeptin A1 productivity in shaking flask cultivations of A. namibiensis, a new cultivation method called salt-enhanced cultivation was used. Compared to the unsupplemented control, labyrinthopeptin A1 productivity was enhanced the most by addition of 50 mM (NH4)2SO4, reaching a 7-fold higher yield of 325 mg L-1 within 10 cultivation days. Salt-enhanced cultivation affected growth and product formation mechanisms, cell morphology characteristics and rheological characteristics of cultivation broth. An image analysis method was developed to quantify both the macro-morphology (pellet size and shape) and the micro-morphology (hyphal network structure) of the heterogeneous filamentous biomass in detail. Productivity-related morphological parameters were in particular the size and circularity of pellets and the degree of hyphal interweaving (hyphal network spacing). It was shown that the time-dependent change in morphology linked to the rheological properties of the cultivation broth. The results presented in this work provide new insights into the cultivation aspects of A. namibiensis and illustrate the challenges on the way to a comprehensive understanding of the complex relationship between productivity, morphology and rheology in filamentous cultivations.
The filamentous actinomycete Lentzea aerocolonigenes produces the antitumor antibiotic rebeccamycin. However, the complex morphology of actinomycetes leads to challenges during the cultivation often accompanied by low product titers. In the recent past, the to date low rebeccamycin titers were increased by particle addition to cultivations of L. aerocolonigenes. In this thesis the addition of micro-, macro- and adsorbent particles to cultivations of L. aerocolonigenes were investigated in more detail. Furthermore, the scale-up to a bubble-free bioreactor was conducted. The addition of glass microparticles (x50 = 7.9 μm, 10 g L-1) to shake flask cultivations increased the rebeccamycin titer up to 3.6-fold compared to an unsupplemented approach. Pellet slices showed the incorporation of microparticles. With different surface modifications of the microparticles, specific incorporation patterns of the microparticles appeared. The incorporation of microparticles causes looser and smaller pellets allowing an increased nutrient and oxygen supply in the pellet core. With addition of larger (glass) macroparticles (ø = 0.2 – 2.1 mm, 100 g L-1) mechanical stress was induced on the biopellets. The additional supplementation of 5 g L-1 soy lecithin and glass beads (ø = 969 μm, 100 g L-1) resulted in a rebeccamycin titer of 388 mg L-1, one of the highest rebeccamycin titers ever achieved. For the scale-up of L. aerocolonigenes cultivations a bubble-free membrane aeration system was developed. The tubular membrane aeration system can additionally be pressurized to increase the oxygen transfer. First cultivations of L. aerocolonigenes successfully provided 18 mg L-1 rebeccamycin, a concentration similar to that of unsupplemented shake flask cultivations. XAD adsorbent particles were added to cultivations to facilitate rebeccamycin recovery. However, the XAD particles additionally increased the rebeccamycin titer which was likely to be caused by the adsorption of the rebeccamycin precursor tryptophan to the resins which in turn directly transferred the tryptophan to the microorganism.
Application of Process Intensification (PI) presents a set of radically innovative principles in process and equipment design, which can bring significant benefits in terms of process efficiency, capital and operating expenses, quality, process safety, and sustainability. Typical approaches in bioprocess intensification are the reduction of the number of production steps, continuous processing, integrated processes, and alternative energy inputs.
This book review series presents current trends in modern biotechnology. The aim is to cover all aspects of this interdisciplinary technology where knowledge, methods and expertise are required from chemistry, biochemistry, microbiology, genetics, chemical engineering and computer science. Volumes are organized topically and provide a comprehensive discussion of developments in the respective field over the past 3-5 years. The series also discusses new discoveries and applications. Special volumes are dedicated to selected topics which focus on new biotechnological products and new processes for their synthesis and purification. In general, special volumes are edited by well-known guest editors. The series editor and publisher will however always be pleased to receive suggestions and supplementary information. Manuscripts are accepted in English.
-Morphology of Filamentous Fungi: Linking Cellular Biology to Process Engineering Using Aspergillus niger, By Rainer Krull, Christiana Cordes, Harald Horn, Ingo Kampen, Arno Kwade, Thomas R. Neu, and Bernd Nörtemann; -Multi-Scale Spatio-Temporal Modeling: Lifelines of Microorganisms in Bioreactors and Tracking Molecules in Cells, By Alexei Lapin, Michael Klann, and Matthias Reuss; -Impact of Profiling Technologies in the Understanding of Recombinant Protein Production, By Chandran Vijayendran and Erwin Flaschel -Engineering the Escherichia coli Fermentative Metabolism, By M. Orencio-Trejo, J. Utrilla, M.T. Fernàndez-Sandoval, G. Huerta-Beristain, G. Gosset, and A. Martinez; -Modeling Languages for Biochemical Network Simulation: Reaction vs Equation Based Approaches, By Wolfgang Wiechert, Stephan Noack, and Atya Elsheikh; -Impact of Thermodynamic Principles in Systems Biology, By J.J. Heijnen;
Bioreaction engineering is fundamental to the optimization of biotechnological processes and the production of biochemicals by enzymes, microbial, plant and animal cells and higher organisms. A reference text for postgraduate students and researchers in biochemical engineering and bioreactor design, Multiphase Bioreactor Design describes the