An optimized semi-defined medium for p-coumaric acid production in extractive fermentation

In this study, the definition and optimization of a medium for cost-effective heterologous production as well as efficient recovery of the plant secondary metabolite p-coumaric acid (p-CA) was performed. Experimental designs were carried out to this end. First, a Plackett Burman design was used to choose the important factors that affect p-CA production. Then, a central composite face centered design was used to find the optima of the two major parameters, C/N ratio and pH. Finally, a four-component optimized semi-defined (OSD) medium was developed and experimented in both biphasic and control batch fermentations. In comparison to the results of previous biphasic fermentations work using a classic defined medium (a 2X Yeast Nitrogen Base medium without Amino Acids), OSD medium was 10 times less expensive per litre. At pH 4.5, the final p-CA production in OSD medium was approximately 61 % of the p-CA content reached in the classic defined medium. At pH 6.0, the production of p-CA in OSD medium was 55 % of the p-CA reached in the YNB medium.