Engineering Aspects of Polyol Biotransformations

Enzymes are already successfully used in many fields of life. For example they are applied for starch degradation, for isomerization of glucose, for aroma production and in cosmetic industry. Main advantages are higher product quality, better raw material exploitation, lower production costs and lower environmental impact [1,2]. As enzymes could already replace chemical catalysts in many fields, research is also done with the aim of using enzymes as catalysts in polymer synthesis, ester oil [3] and fatty acid production.

Applying enzymes on preparative scale is a challenging goal for biotechnology which can lead to new reactor setups for biotransformations. These reactor setups must fulfill requirements like catalyst recycling, mixing, and product removal. This will be discussed and exemplified in the lecture. Catalyst recycling is explored since many years and various separation processes have been developed for enzyme recycling such as membrane technologies and immobilization. Product removal is exploited in numerous synthetic applications from lab to industrial scale. As viscosities for solvent free conversions are high, mixing becomes a crucial issue. Mixing influences reaction rate and conversion. If the reaction medium is not ideally mixed, less substrate can get to the active site of the enzyme and fewer product is formed per unit of time.

Polyols represent versatile substrates for biotransformations. Using various reactants under catalysis of enzymes simple esters as well as complex polymers can be formed. Apart from this also polyols can be obtained from renewable resources applying enzymes. Each of these synthetic routes has their specific requirements mentioned above. Several examples showing the engineering aspects of these polyol biotransformations will be highlighted in the lecture. Up scale of biotransformations like hydrolysis of plant oils [4], solvent free synthesis of ester oils and bulk polymerization [5] will be discussed. Exploiting limiting parameters of bioprocesses lead to improvement in conversion and provide novel reaction pathways.

[1] L. Hilterhaus, A. Liese, Applications of reaction engineering to industrial biotransformations, In: Biocatalysis for the Pharmaceutical Industry (Tao, Lin, Liese eds.) (2009) 65-88
[2] L. Hilterhaus, A. Liese, Bioprocess Development, In: Manual of Industrial Microbiology and Biotechnology 3rd edition (Zhao, sect. ed.) (2010) ASM Press, in press
[3] L. Hilterhaus, O. Thum, A. Liese, Reactor Concept for Lipase-Catalyzed Solvent-Free Conversion of Highly Viscous Reactants Forming Two-Phase Systems. Organic Process Research and Development (2008) 12(4) 618-625
[4] D. Kaufhold, S. Strompen unpublished results
[5] C. Korrup unpublished results