Industrial Biotransformations

Carnitine dehydratase
Escherichia coli
● The mutant strain blocks the l-carnitine dehydrogenase E6 and excretes the accumulated product.
● Only growing cells are active.
● The purified enzymes could not be used for the biotransformation due to their high instability.
● At high product concentration most tested strains show an inhibition and strains with lower
inhibition are not so selective.
● The product tolerance and selectivity could be optimized in a strain development.
● Apart from usual batch fermentations, continuous production is also feasible since the cells go
into a ‘maintenance state’ with high metabolic activity and low growth rate. The cells can be
recycled after separation from the fermentation broth by filtration.
● In the continuous process only 92 % conversion is reached. For almost complete conversions,
fed batch processes are used. As a result, product purification becomes easier.
● Duration of process development: 30 months.
EC 4.2.1.89
● A chemical resolution process that was developed at Lonza was not competitive with the biotechnological
route:
490