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          Institute: MPI für Dynamik komplexer technischer Systeme     Collection: Bioprocess Engineering     Display Documents

ID: 208018.0, MPI für Dynamik komplexer technischer Systeme / Bioprocess Engineering
Vergleich bakterieller Rein- und Mischkulturen in einem 2-L-Rührreaktor in Batch- und Chemostatbetrieb
Authors:Schäfer, B.
Date of Approval (YYYY-MM-DD):2004
Type of Thesis (e.g.Diploma):diplom
Name of University:Fachhochschule
Place of University:Giessen-Friedberg
Audience:Experts Only
Abstract / Description:Microbial communities are the common mode of bacterial existence in natural habitats. As such complex systems become more and more of interest for biotechnology as well as medical and ecological research, there is an increasing need for further knowledge of their behaviour. Three medically relevant bacteria causing lung diseases in cystic fibrosis patients (Burkholderia cepacia, Pseudomonas aeruginosa, Staphylococcus aureus) and a chemically defined medium with glucose as carbon source were chosen as a model system. Pure culture growth characteristics and kinetic parameters were determined using 250 mL shake flasks. During growth of S. aureus acetate and pyruvate accumulated in culture medium. Biomass formation in B. cepacia and P. aeruginosa cultivations could be increased by addition of sodium acetate as an additional carbon source. A scale-up for the model organisms was carried out from shake flask scale into a 2 L stirred tank reactor (STR) using exhaust gas analysis for calculation of oxygen transfer rate (OTR), carbon dioxide transfer rate (CTR) and respiratory quotient (RQ). Pure culture cultivations in the STR showed less biomass formation of P. aeruginosa and S. aureus compared to shake flask experiments. OTR- and RQ-characteristics indicated metabolic differences between the model organisms. A continuous cultivation set up was established as a standard procedure for cultivation of a defined mixed culture. The inoculation strategy showed reproducible results for cultivations. RQ-behaviour indicated metabolic changes for mixed cultures at different dilution rates. Using kinetic parameters derived form pure culture experiments, a computer based simulation for competition of three species growing on one limiting substrate in a chemostat showed similar results compared to experimental data of mixed cultivations.
Document Type:Thesis
Communicated by:Udo Reichl
Affiliations:MPI für Dynamik komplexer technischer Systeme/Bioprocess Engineering
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