Exploring the potential of fungal arylacetonitrilases in mandelic acid synthesis.

摘要: The application of arylacetonitrilases from filamentous fungi to the hydrolysis high concentrations (R,S)-mandelonitrile (100–500 mM) was demonstrated for first time. Escherichia coli strains expressing corresponding genes were used as whole-cell catalysts. Nitrilases Aspergillus niger, Neurospora crassa, Nectria haematococca, and Arthroderma benhamiae (enzymes NitAn, NitNc, NitNh, NitAb, respectively) exhibited different degrees enantio- chemoselectivity (amide formation). Their increased by increasing pH (from 8 9–10) adding 4–10 % (v/v) toluene cosolvent. NitAn NitNc able convert an up 500 mM substrate in batch mode. formed a very low amount by-product, amide ( 70 g/L (R)-mandelic acid (e.e. 94.5–95.6 %) or fed-batch Its volumetric productivities highest mode [571 ± 32 g/(L d)] its catalyst (39.9 2.5 g/g dcw). NitAb hydrolyzed both enantiomers 100 at 5.0 is therefore promising enantioretentive transformation (S)-mandelonitrile. Sequence analysis suggested that fungal with similar properties (enantioselectivity, chemoselectivity) clustered together.