Biocatalysis and fermentation

The number of newly identified or characterized enzymes continually grows thus improving the spectrum of enzymatic reactions on a nearly daily basis. Nevertheless, from a biotechnological point of view we are far away from having available an appropriate biocatalyst for any conversion of a given substrate to a specific product. Additionally, not every available enzyme capable of catalyzing a given reaction is suitable for an industrial and economic application, due to low activity or stability. We therefore try (1) to identify new enzymes and (2) to modulate their relevant characteristics to optimize them for a technical process. But when designing biocatalysts it’s not all about modifying individual enzymes via protein engineering. Frequently, specifically tailored cell factories developed via cell engineering come into play. Whole cell catalysts can be highly attractive for biotechnology from an economical point of view. However, problems may arise due to unwanted metabolic side reactions of the cell or insufficient mass transport of necessary substrates over the cell membrane. Such limitations can be overcome by modifications of the host cell.

The application of current methods of protein engineering and cell engineering facilitate the tailored design of suitable biocatalysts for technical purposes. However, for the implementation of production processes that represent a technology comparable or even superior to traditional chemical catalysis, the sole focus on molecular characteristics is not sufficient. Bioprocess engineering is an important factor to be considered for the development of novel and optimized processes and to exploit the full potential of the employed biocatalysts.