Enhanced (R)-2-(4-Hydroxyphenoxy)Propionic Acid Production by Beauveria bassiana: Optimization of Culture Medium and H2O2 Supplement Under Static Cultivation.

Abstract

(R)-2-(4-hydroxyphenoxy)propionic acid (HPOPA) is a key intermediate for the preparation of aryloxyphenoxypropionic acid herbicides (R-isomer). In order to improve the HPOPA production from the substrate (R)-2-phenoxypropionic acid (POPA) with Beauveria bassiana CCN-A7, static cultivation and H2O2 addition were attempted and found to be conducive to the task at hand. This is the first report on HPOPA production under static cultivation and reactive oxygen species (ROS) induction. On this premise, the cultivation conditions and fermentation medium compositions were optimized. As a result, the optimal carbon source, organic nitrogen source, and inorganic nitrogen source were determined to be glucose, peptone, and ammonium sulfate, respectively. The optimal inoculum size and fermentation temperature were 13.3% and 28°C, respectively. The significant factors including glucose, peptone, and H2O2, identified based on Plackett-Burman design, were further optimized through Central Composite Design (CCD). The optimal concentrations/amounts were as follows: glucose 38.81 g/l, peptone 7.28 g/l, and H2O2 1.08 ml/100 ml. Under the optimized conditions, HPOPA titer was improved from 9.60 g/l to 19.53 g/l, representing an increase of 2.03- fold. The results obtained in this work will provide novel strategies for improving the biosynthesis of hydroxy aromatics.