A study in UF-membrane reactor on activity and stability of nitrile hydratase from Microbacterium imperiale CBS 498-74 resting cells for propionamide production

摘要: Abstract The bioconversion of propionitrile to propionamide was catalysed by nitrile hydratase (NHase) using resting cells Microbacterium imperiale CBS 498-74 (formerly, Brevibacterium imperiale). This microorganism, cultivated in a shake flask, at 28 °C, presented specific NHase activity 34.4 U mgDCW−1 (dry cell weight). kinetic parameters, Km and Vmax, tested 50 mM sodium phosphate buffer, pH 7.0, the evaluated batch reactor 10 °C resulted 21.6 mM 11.04 μmol min−1 mgDCW−1, respectively. measured apparent activation energy, 25.54 kJ mol−1, indicated partial control mass transport, more likely through wall. UF-membrane reactors were used for characterisation reaction. time dependence enzyme deactivation on reaction temperature (from 5 25 °C), substrate concentrations 100 800 mM), loading 1.5 200 μg DCW  ml−1) indicated: lower diffusional (Ea=37.73 kJ mol−1); irreversible damage caused high concentration. Finally, it is noteworthy that an integral continuously operating 30 h, 10 °C, 100% conversion (200 mM) attained  ml−1 cells, with maximum volumetric productivity 0.5 g l−1 h−1.