Development of nitrilase-mediated process for phenylacetic acid production from phenylacetonitrile

摘要

This study aimed at developing an efficient biotransformation process for phenylacetic acid production from phenylacetonitrile by using recombinant Escherichia coli M15 harboring a double mutant MG nitrilase (I113M/Y199G) from Burkholderia cenocepacia J2315. A yield of 2310 U/mL nitrilase was obtained by fermentation after the optimization of cultivation conditions, with a specific activity of 64 U/mg dcw. The MG nitrilase showed high substrate tolerance and completely hydrolyzed 100 mM phenylacetonitrile in 30 min under optimal conditions. To alleviate substrate inhibition, periodic or continuous batch-feeding of substrate was used during the biotransformation. Up to 164 g/L substrate was completely hydrolyzed in 9 h with continuous batch-feeding using resting cells, corresponding to 400 U/mL of nitrilase activity, and leading to production of 163.4 g/L phenylacetic acid. The hydrolysis process has potential application for phenylacetic acid production on a large scale.