title: Efficient production of (R)-(-)-mandelic acid using glutaraldehyde cross-linked Escherichia coli cells expressing Alcaligenes sp. nitrilase.
abstract: Recombinant Escherichia coli cells expressing Alcaligenes sp. nitrilase were simply immobilized by direct cross-linking using glutaraldehyde. About 85 % of the total nitrilase activity was recovered under the optimal cross-linking conditions. The thermal stabilities of the cross-linked cells measured at 30, 40 and 50 °C were 4.5-, 5.3-, and 5.1-fold those of the free cells, respectively. The concentration of (R)-(-)-mandelic acid reached 280 mM after merely 2 h transformation with the immobilized cells using 300 mM mandelonitrile as substrate, affording an extremely high productivity of 510.7 g L(-1) d(-1). In addition, operational stability of the immobilized cells was obviously superior to that of free cells, without significant activity loss after 15 cycles of batch reactions or 8 cycles of repeated fed-batch reactions. Therefore, the easy preparation and robust characteristics of the immobilized biocatalyst make it a very promising biocatalyst for high-performance and low-cost production of optically pure (R)-(-)-mandelic acid.
authors: Laboratory of Biocatalysis and Synthetic Biotechnology, State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai, 200237, China.
authors: Zhi-Jun
authors: ZJ
authors: Zhang
authors: Jiang
authors: J
authors: Pan
authors: Chun-Xiu
authors: CX
authors: Li
authors: Hui-Lei
authors: HL
authors: Yu
authors: Gao-Wei
authors: GW
authors: Zheng
authors: Xin
authors: X
authors: Ju
authors: Jian-He
authors: JH
authors: Xu
mesh_terms: D000097:Acetonitriles / Q000737:chemistry; D000421:Alcaligenes / Q000201:enzymology*; D000619:Aminohydrolases / Q000737:chemistry*; D002384:Catalysis; D003432:Cross-Linking Reagents / Q000737:chemistry; D004305:Dose-Response Relationship, Drug; D004798:Enzymes / Q000737:chemistry; D004800:Enzymes, Immobilized; D004926:Escherichia coli / Q000378:metabolism*; D005976:Glutaral / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008333:Mandelic Acids / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
chemical_list: D000097:Acetonitriles; D003432:Cross-Linking Reagents; D004798:Enzymes; D004800:Enzymes, Immobilized; D008333:Mandelic Acids; C045516:mandelonitrile; D000619:Aminohydrolases; C021867:nitrilase; C037938:mandelic acid; D005976:Glutaral