Fermentation Technology - apl. Prof. Dr. Karl Friehs

The work group Fermentation Technology is headed by apl. Prof. Dr. Karl Friehs. Fermentation engineering, downstream processing of proteins and plasmid DNA as well as enzyme engineering and metabolic engineering are in the focus of research. The AG is directly connected with the Bielefelder Centrum für Biotechnologie (CeBiTec) due the technology platform fermentation and supports other groups in large scale cultivations. Dr. Joe Max Risse is the head of the platform. The production of extracellular proteins by means of Gram negative bacteria is one of the main aims. For these purpose methods of genetic engineering, bioengineering and reaction engineering are applied. Novel research areas are represented by the aerobic microbial degradation of oil and fat, the development of phototrophic processes as well as the generation of biogas.

Cultivation of Microorganisms
Gram-negative and Gram-positive bacteria as well as different eukaryotes have been grown in submerse culture systems. These organisms include Escherichia coli, Klebsiella planticola, different Bacillus sp., Streptomyces sp., Pichia pastoris and protozoaes as Euglena gracilis. Cultivation conditions and operating strategies have been optimized in order to obtain maximal concentrations of products like recombinant proteins, plasmid DNA or polysaccharides. Biorefinery concepts are current research targets. The production of high-value materials in phototrophic cultivation systems like algae is in the focus of present research efforts. Residues thereof are offered to special microorganism communities in biogas processes.

Downstream Processing
Research targets in this area are the separation and purification of, primarily, recombinant proteins and plasmid-DNA, but also of special polysaccharides. Recombinant proteins include the whole range from industrial enzymes for use in biofuel processes to human transcription factors of interest in stem cell research. The main aim consists in achieving secretion of recombinant proteins into the extracellular space with Gram-negative bacteria. This is achieved by coexpressing bacteriocin release proteins which lead to rendering the outer membrane permeable. A newer way is the construction and characterization of metabolic engineered secretion strains. Different pseudo-affinity interactions are used for adsorptive as well as extractive downstream processes. Extraction processes are of particular interest even in the case of plasmid DNA separation. Plasmid DNA is processed for being applicable as vectors in gene therapy and genetic vaccination.

Metabolic Engineering
Using applied molecular genetics strains are constructed to produce specific proteins or metabolites. These strains are checked for their performance in high cell density cultivations for optimized productivity. To analyze the interaction of recombinant strains and cultivation conditions is an intensive pushed research topic.

 

Publications