Bench scale synthesis of p -hydroxybenzoic acid using whole-cell nitrilase of Gordonia terrae mutant E9

摘要: Mutants of Gordonia terrae were generated using chemical mutagens for better activity, stability and higher substrate/product tolerance its nitrilase enzyme. Mutant E9 showed two-time increase in activity tolerated p-hydroxybenzonitrile (p-HBN) up to 50 mM. Response surface methodology inducer mediation approach further enhanced the production enzyme 2.5-fold. The bench scale p-hydroxybenzoic acid (p-HBA) was carried out a fed-batch reaction (500-mL scale) whole-cell mutant 0.1 M potassium phosphate buffer (pH 8.0) at 40 °C. Total six feedings each an interval 45 min resulted accumulation 360 mM (21.6 g) p-HBA with purity 99 %. catalytic volumetric productivity bioprocess G. improved 1.8 g h−1 g DCW −1 43.2 g L−1, respectively, from 0.78 g h−1 g 28.8 g L−1 resting cells wild strain. K m V max purified 55 U mg−1 1.8 mM p-HBN turnover number 36 s−1 × 10−3.