Scale-up of docosahexaenoic acid production in fed-batch fermentation by Schizochytrium sp. based on volumetric oxygen-transfer coefficient

The scale-up of fed-batch fermentation process for the DHA (docosahexaenoic acid)-rich microbial lipids production by Schizochytrium sp. from shake flasks to bench-scale (10l and 50l) and pilot-scale (1500l and 7000l) stirred fermentors was studied. The fermentation process was successfully scaled-up from experimental-scale to bench-scale and pilot-scale at matched K_La value (88.9h^-1) estimated by the K_La model developed in this study and the K_La empirical equations. The fermentation performances of the bench-scale and pilot-scale (DHA content of 13.96, 14.44 and 14.16gl^-1 in the 10l, 50l and 1500l fermentor) processes were similar to that of the experimental-scale process (DHA content of 13.84gl^-1) and the fermentation results obtained in the 7000l stirred fermentors (DHA content of 19.72gl^-1) were much higher. These results indicated that K_La was applicable for the scale-up of the fed-batch fermentation process of DHA production by Schizochytrium sp. and this scale-up strategy enabled a maximum of 150-fold quantitative scale-up of the fed-batch fermentation process.