Efficient biocatalytic synthesis of nicotinic acid by recombinant nitrilase via high density culture

[Display omitted] •The nitrilase was constitutively expressed in E. coli.•The nitrilase activity was improved by 14.9-fold via high density culture.•The nicotinic acid synthesized by nitrilase was the highest level to date. The constitutively expression system for P. putida nitrilase was firstly constructed to improve the nicotinic acid production and reduce the production costs. High density culture strategy was employed to enhance the biomass and nitrilase production of recombinant strain. The total nitrilase activity reached up to 654 U·mL−1 without the induction. 541 g·L−1 nicotinic acid was accumulated via fed batch mode of substrate feeding through 290 min of conversion.