Lecture : BioCatalysis in Pichia
Whole-cell biotransformations employing recombinant microorganisms are an elegant and scalable possibility to employ enzymes in the synthesis of highly valuable compounds. Using whole cells as biocatalysts is advantageous is many aspects: time-consuming enzyme isolation and purification steps can be circumvented, within the cell the enzyme is protected from shear forces and organic solvents and the cell metabolism can be exploited for cofactor regeneration .
The potential of Pichia pastoris as whole-cell biocatalyst will be illustrated by two examples: By cellular targeting we succeeded in the generation of a D-amino acid oxidase based catalyst displaying an enhanced specific activity and robustness in comparison to isolated enzyme preparations [2,3]. On the other hand, in a comparative study we have evaluated the potential of four different microbial systems expressing the membrane-bound human cytochrome P450 2D6/P450 reductase complex for applications in drug metabolite synthesis. P. pastoris turned out to be the most efficient expression host, which was successfully used for the synthesis of steroid metabolites [4,5].
To further promote the use of P. pastoris as whole-cell biocatalyst our current research is focused on the generation of novel chassis strains with beneficial features such as improved cofactor regeneration and the use of Pichia to express heterologous and synthetic pathways for valuable compound synthesis.
 Duetz, W. A., van Beilen, J. B., and Witholt, B., 2001, Curr Opin Biotechnol, 12, 419-425.
 Abad, S., Nahalka, J., Bergler, G., Arnold, S.A., Speight, R., Fotheringham, I., Nidetzky, B., and Glieder, A., 2010, Microb Cell Fact, 9.
 Abad, S., Nahalka, J., Winkler, M., Bergler, G., Speight, R., Glieder, A., and Nidetzky, B., 2011, Biotechnol Lett, 33,557-63.
 Geier, M., Braun, A., Emmerstorfer, A., Pichler, H., and Glieder A., 2012, Biotechnol J, 7, 1346-58.
 Geier, M., Braun, A., Fladischer, P., Stepniak, P., Rudroff, F., Hametner, C., Mihovilovic, M.D., and Glieder, A., 2013, FEBS J, 280, 3094-108.
Acknowledgements: The research leading to these results has received funding from the EU-FP7 project OXYGREEN (EC Grant 212281) as well as from the CHEM21 project, an Innovative Medicines Initiative Joint Undertaking under grant agreement n°115360, resources of which are composed of financial contribution from the European Union’s Seventh Framework Programme (FP7/2007-2013) and EFPIA companies’ in-kind contribution. This work has been furthermore supported by the Federal Ministry of Economy, Family and Youth (BMWFJ), the Federal Ministry of Traffic, Innovation and Technology (bmvit), the Styrian Business Promotion Agency SFG, the Standortagentur Tirol and ZIT - Technology Agency of the City of Vienna through the COMET-Funding Program managed by the Austrian Research Promotion Agency FFG.