The total yield of ergosterol produced by the fermentation of the yeast Saccharomyces cerevisiae depends on the final amount of yeast biomass and the ergosterol content in the cells. At the same time ergosterol purity-defined as percentage of ergosterol in the total sterols in the yeast-is equally important for efficient downstream processing. This study investigated the development of both the ergosterol content and ergosterol purity in different physiological (metabolic) states of the microorganism S. cerevisiae with the aim of reaching maximal ergosterol productivity. To expose the yeast culture to different physiological states during fermentation an on-line inference of the current physiological state of the culture was used. The results achieved made it possible to design a new production strategy, which consists of two preferable metabolic states, oxidative-fermentative growth on glucose followed by oxidative growth on glucose and ethanol simultaneously. Experimental application of this strategy achieved a value of the total efficiency of ergosterol production (defined as product of ergosterol yield coefficient and volumetric productivity), 103.84 × 10-6 g L-1 h-1 , more than three times higher than with standard baker's yeast fed-batch cultivations, which attained in average 32.14 × 10-6 g L-1 h-1 . At the same time the final content of ergosterol in dry biomass was 2.43%, with a purity 86%. These results make the product obtained by the proposed control strategy suitable for effective down-stream processing. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:838-848, 2017.

• Klíčová slova
• Saccharomyces cerevisiae yeast, bioprocess control, ergosterol production, knowledge-based control, physiological control,
• MeSH
• biomasa MeSH
• bioreaktory mikrobiologie   MeSH
• ergosterol metabolismus   MeSH
• ethanol metabolismus   MeSH
• fermentace fyziologie   MeSH
• Saccharomyces cerevisiae metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ergosterol MeSH
• ethanol MeSH

Fed-batch is the most commonly used cultivation mode for industrial production of recombinant proteins with Pichia pastoris. On a laboratory scale, fed-batch culture provides a way to control the specific biomass growth rates at any pre-set value, allowing the conditions of biomass growth and recombinant product formation to be systematically studied.In this chapter, we present an accessible and versatile approach for designing, performing, and evaluating a fed-batch cultivation in laboratory-scale stirred tank bioreactors.

• Klíčová slova
• Bioprocess design and development, Bioreactor, Data evaluation, Fed-batch culture, Feed rate, Fermentation, Komagataella phaffii, Pichia pastoris, Specific growth rate, Specific productivity,
• MeSH
• biomasa MeSH
• bioreaktory mikrobiologie   MeSH
• fermentace MeSH
• kultivační média MeSH
• Pichia * růst a vývoj   MeSH
• rekombinantní proteiny genetika   biosyntéza   MeSH
• Saccharomycetales * růst a vývoj   metabolismus   MeSH
• techniky vsádkové kultivace * metody   MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• kultivační média MeSH
• rekombinantní proteiny MeSH

Design and development of scale-down approaches, such as microbioreactor (μBR) technologies with integrated sensors, are an adequate solution for rapid, high-throughput and cost-effective screening of valuable reactions and/or production strains, with considerably reduced use of reagents and generation of waste. A significant challenge in the successful and widespread application of μBRs in biotechnology remains the lack of appropriate software and automated data interpretation of μBR experiments. Here, it is demonstrated how mathematical models can be usedas helpful tools, not only to exploit the capabilities of microfluidic platforms, but also to reveal the critical experimental conditions when monitoring cascade enzymatic reactions. A simplified mechanistic model was developed to describe the enzymatic reaction of glucose oxidase and glucose in the presence of catalase inside a commercial microfluidic platform with integrated oxygen sensor spots. The proposed model allowed an easy and rapid identification of the reaction mechanism, kinetics and limiting factors. The effect of fluid flow and enzyme adsorption inside the microfluidic chip on the optical sensor response and overall monitoring capabilities of the presented platform was evaluated via computational fluid dynamics (CFD) simulations. Remarkably, the model predictions were independently confirmed for μL- and mL- scale experiments. It is expected that the mechanistic models will significantly contribute to the further promotion of μBRs in biocatalysis research and that the overall study will create a framework for screening and evaluation of critical system parameters, including sensor response, operating conditions, experimental and microbioreactor designs.

• Klíčová slova
• Bioprocess modeling, Computational fluid dynamics, Enzymatic biocatalysis, Mechanistic modeling, Microbioreactor, Oxygen monitoring,
• MeSH
• biokatalýza MeSH
• biologické modely * MeSH
• bioreaktory * MeSH
• glukosaoxidasa metabolismus   MeSH
• katalasa metabolismus   MeSH
• mikrofluidní analytické techniky * MeSH
• optická vlákna * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• glukosaoxidasa MeSH
• katalasa MeSH