Bioprocess Development for the Synthesis of 4-Aminophenylacetic Acid Using Nitrilase Activity of Whole Cells of Alcaligenes faecalis MTCC 12629

Nitrilases are important industrial enzymes to synthesize commercially useful acids from nitriles. In the present study, an aryl specific inducible nitrilase was produced from Alcaligenes faecalis MTCC 12629 which hydrolyzed 4-aminophenylacetonitrile to 4-aminophenylacetic acid. A bioprocess was developed to synthesize 4-aminophenylacetic acid from 4-aminophenylacetonitrile at 500 ml scale under optimized reaction conditions. The maximum activity of nitrilase for biotransformation of 4-aminophenylacetonitrile was recorded in 50 mM KH2PO4/K2HPO4 buffer of pH 7 at 45 °C. Operational stability of present enzyme was found at 45 °C for fed batch reaction. The bioprocess designed at 500 ml scale included 17 U/ml catalyst amount, 50 mM substrate addition after 30 min in total five feedings for 150 min at 45 °C. The approach of substrate feeding at lower amount resulted in accumulation of 175 mM product in 500 ml reaction after five feedings of substrate. The rate of product formation was found to be 2.5 g/gdcw/h with the volumetric productivity of 26.6 g/l.