Whole-cell biocatalysis in the presence of ionic liquids

Holger Pfründer, doctoral thesis Technische Universität München, 2005

Whole-cell biocatalysis represents an elegant way of producing fine chemicals. However, the development of economic processes is often impeded by substrates and products that are poorly soluble in water and display toxic effects on the biocatalyst. Considering the asymmetric reduction of ketones as example, it was shown in this work that the use of ionic liquids as solvent can be the answer to this problem. Ionic liquids dissolve ketones and alcohols very well and, in contrast to commonly used organic solvents, cause no damage to the microorganisms. Therefore, these room temperature molten salts can be employed as substrate reservoir and in situ extracting agent for whole cell biocatalytic reactions. By this means more efficient processes can be developed. For instance, the yield and the enantiomeric excess in the production process of (R)-1-(4- chlorophenyl)ethanol could be increased from 46 % to 93 % and from 98,1 % to 99,7 %, respectively.

Publications

• Pfruender H, Jones R, Weuster-Botz D (2006): Water immiscible ionic liquids as solvents for whole cell biocatalysis. J Biotechnol 124: 182-190.
• Pfruender H, Amidjojo M, Hang F, Weuster-Botz D (2005): Production of Lactobacillus kefir cells for asymmetric synthesis of a 3,5-dihydroxycarboxylate. Appl Microbiol Biotechnol 67: 619-622.
• Pfründer H, Amidjojo M, Kragl U, Weuster-Botz D (2004): Effiziente Ganzzell-Biotransformation im zweiphasigen System ionische Flüssigkeit/Wasser. Angew Chem 116: 4629-4631.
• Pfruender H, Amidjojo M, Kragl U, Weuster-Botz D (2004): Efficient whole-cell biotransformation in a biphasic ionic liquid/water system. Angew Chem Int Ed 43: 4529-4531.