Threonine aldolase (TA) from Thermotoga maritima was immobilized on Eupergit support by both a direct and an indirect method. The incubation time for the direct immobilization method was optimized for the highest amount of enzyme on the support. By introducing the immobilized TA in a packed-bed microreactor, a flow synthesis of phenylserine was developed, and the effects of temperature and residence time were studied in particular. Calculations of the Damköhler number revealed that no mass transfer limitations are given in the micro-interstices of the packed bed. The fact that the yield does not >40% is then rather explained by the equilibrium nature of the reaction and substrate inhibition which is experimentally proven. The flow synthesis with the immobilized enzyme was compared to one using free enzyme. The product yield was further improved by operating under slug flow conditions which is related to the very short residence time distribution. In all cases 20% diastereomeric excess (de) and 99% enantio¬meric excess (ee) was observed. A continuous run of the reactant solution was carried out for 10 hours in order to check the stability of enzyme at higher temperature with stable operation at 20 minute residence time. Finally, the productivity of the reactor was calculated, extrapolated to parallelly run units, and compared with result in a previous publication.
|Title of host publication||Proceedings of the 2nd International Conference Implementation of Microreactor Technology in Biotechnology, 5-8 May 2013, Cavtat, Croatia|
|Publication status||Published - 2013|
|Event||conference; IMTB 2013 - Croatia - Cavtat - |
Duration: 1 Jan 2013 → …
|Conference||conference; IMTB 2013 - Croatia - Cavtat|
|Period||1/01/13 → …|
|Other||IMTB 2013 - Croatia - Cavtat|