Stabilizing whole-cell biocatalysts

Whole-cell biocatalysts offer great potential for the development of sustainable processes that are difficult to achieve chemically and can replace or complement traditional chemical and pharmaceutical processes. However, microbial cells are not evolved for the production of industrially-relevant compounds, which often exert toxicity and therefore destabilize wholecell biocatalysts. In order to overcome limitations related to stability and to exploit the full potential of whole-cell biocatalysts, a concerted strategy combining pathway, cellular, reaction, and process engineering has to be pursued. In this thesis, a microbial oxyfunctionalization reaction was selected as a model bioprocess system to understand the mechanisms that affect the stability of whole-cell biocatalysts in a bioprocess and to exemplarily show selective engineering approaches to overcome such stability influencing factors. Respective biocatalysts were based on genetically modified E. coli containing the alkane monooxygenase system AlkBGT and the outer membrane protein AlkL from P. putida GPo1, enabling oxyfunctionalization of renewable fatty acid methyl esters (FAMEs).