Nitrilase-catalyzed conversion of (R,S)-mandelonitrile by immobilized recombinant Escherichia coli cells harboring nitrilase

摘要: (R)-(-)-Mandelic acid (R-MA) is widely used both as a versatile intermediate for pharmaceuticals and resolving agent in chiral resolution processes. In the current study, to improve stability of operation, recombinant Escherichia coli cells expressing nitrilase from Alcaligenes faecalis were immobilized enantioselective hydrolysis (R,S)-mandelonitrile R-MA. Different immobilization methods including entrapment matrices, matrices cross-linked by cross-linking polymerization agents, direct using glutaraldehyde (GA) or bionic silicon investigated. To facilitate industrial solid-liquid separation, E. diatomite/GA/polyethyleneimine with 135.95% relative activity compared free was chosen water reaction medium. The operational obviously superior that cells, without significant loss after 28 cycles batch successive production R-MA could reach 1.88 M. Moreover, showed good storage about 52% storing 30 days at 4 °C. Therefore, biocatalyst very promising upscale optically pure high performance low cost.