Evaluation of spray cycle bioreactor using L-alanine degradation by Candida maltosa

The oxygen-supply capability of a spray cycle reactor was evaluated by using it for oxidative degradation of L-alanine. The volumetric oxygen transfer coefficient, kLa, was evaluated as a parameter for the oxygen supply. The liquid circulation rate in the spray cycle reactor was represented in terms of the number of circulations. The kLa increased with the number of circulations, especially by stirring in the reservoir vessel, reaching 272/h at 4.4/min of circulation numbers. This value was 1.4 times higher than that without stirring. The L-alanine degradation rate increased as the cell growth was promoted, and as the circulation numbers increased. Finally, the spray cycle reactor was evaluated by the specific degradation rate. This rate increased in proportion to the kLa, and was 8.8 times higher than that in the jar fermentor, suggesting that the spray cycle reactor is superior for oxygen-demanding fermentation.