Walter Gulik
257 records found
1
Authored
Microbioreactors for nutrient-controlled microbial cultures
Bridging the gap between bioprocess development and industrial use
It is common practice in the development of bioprocesses to genetically modify a microorganism and study a large number of resulting mutants in order to select the ones that perform best for use at the industrial scale. At industrial scale, strict nutrient-controlled growth co ...
Understanding of thermal adaptation mechanisms in yeast is crucial to develop better-adapted strains to industrial processes, providing more economical and sustainable products. We have analyzed the transcriptomic responses of three Saccharomyces cerevisiae strains, a commerci ...
Fed-Batch Droplet Nanobioreactor for Controlled Growth of Cyberlindnera (Pichia) jadinii
A Proof-Of-Concept Demonstration
A key bottleneck in bioprocess development is that state-of-the-art tools used for screening of cells and optimization of cultivation conditions do not represent the conditions enforced at industrial scale. At industrial scale, cell growth is strictly controlled (“fed-batch”) ...
Co-fermentation of sugarcane bagasse hydrolysate and molasses by Clostridium saccharoperbutylacetonicum
Effect on sugar consumption and butanol production
Co-fermentation of mixed sugars to produce butanol is an attractive route in sucrochemical production chains. Herein, high-level mixed sugars from sugarcane bagasse hemicellulosic hydrolysate (HH) and molasses (SCM) were investigated as potential substrates for acetone-butanol ...
A phenotypic screening of 12 industrial yeast strains and the well-studied laboratory strain CEN.PK113-7D at cultivation temperatures between 12 °C and 40 °C revealed significant differences in maximum growth rates and temperature tolerance. From those 12, two strains, one per ...
The wild type strain Trichoderma harzianum was able to synthesize enzymes that can catalyse the hydrolysis of p-nitrophenyl-β-D-glucopyranoside (PNPGase) in glucose-limited chemostat cultures. Fructose/glucose and sucrose conditions provided low levels of PNPGase activity. To ...
Physiological responses of Saccharomyces cerevisiae to industrially relevant conditions
Slow growth, low pH, and high CO2 levels
Engineered strains of Saccharomyces cerevisiae are used for industrial production of succinic acid. Optimal process conditions for dicarboxylic-acid yield and recovery include slow growth, low pH, and high CO2. To quantify and understand how these process parameters ...
Computational fluid dynamics simulation of an industrial P. chrysogenum fermentation with a coupled 9-pool metabolic model
Towards rational scale-down and design optimization
We assess the effect of substrate heterogeneity on the metabolic response of P. chrysogenum in industrial bioreactors via the coupling of a 9-pool metabolic model with Euler-Lagrange CFD simulations. In this work, we outline how this coupled hydrodynamic-metabolic modeling can ...
Power input effects on degeneration in prolonged penicillin chemostat cultures
A systems analysis at flux, residual glucose, metabolite, and transcript levels
In the present work, by performing chemostat experiments at 400 and 600 RPM, two typical power inputs representative of industrial penicillin fermentation (P/V, 1.00 kW/m3 in more remote zones and 3.83 kW/m3 in the vicinity of the impellers, respectively) ...
Comparative performance of different scale-down simulators of substrate gradients in Penicillium chrysogenum cultures
The need of a biological systems response analysis
In a 54 m3 large-scale penicillin fermentor, the cells experience substrate gradient cycles at the timescales of global mixing time about 20–40 s. Here, we used an intermittent feeding regime (IFR) and a two-compartment reactor (TCR) to mimic these substrate gradien ...
Bioprocess scale-up/down as integrative enabling technology
From fluid mechanics to systems biology and beyond
Efficient optimization of microbial processes is a critical issue for achieving a number of sustainable development goals, considering the impact of microbial biotechnology in agrofood, environment, biopharmaceutical and chemical industries. Many of these applications require ...
In its natural environment, the filamentous fungus Aspergillus niger grows on decaying fruits and plant material, thereby enzymatically degrading the lignocellulosic constituents (lignin, cellulose, hemicellulose, and pectin) into a mixture of mono- and oligosaccharides. To in ...
Enzymic analysis of NADPH metabolism in β-lactam-producing Penicillium chrysogenum
Presence of a mitochondrial NADPH dehydrogenase
MIRACLE
Mass Isotopomer Ratio Analysis of U-13C-Labeled Extracts. A New Method for Accurate Quantification of Changes in Concentrations of Intracellular Metabolites
First, we report the application of stable isotope dilution theory in metabolome characterization of aerobic glucose limited chemostat culture of S. cerevisiae CEN.PK 113-7D using liquid chromatography - electrospray ionization MS/MS (LC-ESI-MS/MS). A glucose-limited chemostat ...
Continuous cultures limited by a gaseous substrate
Development of a simple, unstructured mathematical model and experimental verification with Methanobacterium thermoautotrophicum
This article presents a simple, unstructured mathematical model describing microbial growth in continuous culture limited by a gaseous substrate. The model predicts constant gas conversion rates and a decreasing biomass concentration with increasing dilution rate. It has been ...