Exploiting solvent tolerance for productive whole-cell biocatalysis

In the PhD thesis of Jan Volmer, the biocatalytic performance of solvent tolerant Pseudomonas sp. strain VLB120 for recombinant whole-cell biocatalysis with toxic reactants is evaluated. The investigated strain is characterized with respect to its solvent tolerance mechanisms (in silico), its solvent tolerance towards different toxic compounds (e.g., toluene, octanol), and its adaptation behavior. As a main goal, a constitutive solvent tolerant Pseudomonas sp. strain VLB120 mutant will be constructed by genetic engineering (e.g., regulation of solvent efflux pumps), which does not need tedious adaptation procedures to develop a solvent tolerant phenotype. The resulting mutants will be characterized with respect to their biocatalytic performance with different toxic reactants in various setups such as two-liquid phase biotransformations. Furthermore, potential limitations of such constitutively solvent tolerant strains such as a competition for energy between solvent tolerance mechanisms and enzymes involved in biocatalysis or active efflux of inducing agents and substrates are elucidated, and alternatives such as non-energy depending solvent tolerance mechanisms will be investigated and applied.