Design of a spray-cycle bioreactor and its application for riboflavin production

摘要

A highly efficient spray-cycle reactor for oxygen supply was developed. A typical arrangement of the reactor consists of a spray column fitted with a nozzle and a coaxal tube, and a reservoir vessel. The culture broth was circulated between the column and vessel by a peristaltic pump. The volumetric oxygen-transfer coefficient, k(1)a was evaluated as a parameter for oxygen supply. The liquid circulation rate in the spray-cycle reactor was represented in terms of the number of circulations. The k(1)a value increased as the number of circulations increased, reaching 208 h(-1) at 4.4 min(-1) of circulation numbers. This value was 1.8 times higher than that in a 1500-mL stirred-tank reactor under the agitation of 20.7g and the aeration of 1.0 volume per min. The spray-cycle reactor was applied to riboflavin production by an aerobic microorganism. The riboflavin production increased as k,a values increased and the maximal riboflavin production was 161 mg/L at 208 h(-1) of k(1)a. These results suggest that the spray-cycle reactor is useful to oxygen-demanding fermentation because of the high k(1)a value in comparison with the stirred-tank reactor. [References: 9]