Continuous gluconic acid production by the yeast-like Aureobasidium pullulans in a cascading operation of two bioreactors

Abstract The application of a new developed process for the continuous production of gluconic acid using a cascade of two bioreactors in a continuous process is shown reaching the highest concentration of gluconic acid described in the literature for continuous culture fermentation. Very high glucon...
Ausführliche Beschreibung

Abstract The application of a new developed process for the continuous production of gluconic acid using a cascade of two bioreactors in a continuous process is shown reaching the highest concentration of gluconic acid described in the literature for continuous culture fermentation. Very high gluconic acid concentrations of 272–308 g/l have been achieved under continuous cultivation of free-growing cells of Aureobasidium pullulans in the first bioreactor at residence times (RT) between 19.5 and 24 h with formation rates for the generic product between 12.7 and 13.9 g/(l h). Gluconic acid, 350–370 g/l, was continuously reached in the second bioreactor at a total RT of 30.8–37 h with Rj of 9.2–12 g/(l h). The highest specific gluconic acid production (mp) of 3.6 g/(g h) was found in the first bioreactor at the lowest RT of 19.5 h. The highest selectivity of 93.6% was determined in the first bioreactor as well. Complete glucose consumption was obtained at 37 h total residence time in the second bioreactor. Gluconic acid, 433 g/l, was continuously produced in the second bioreactor at a total RT of 37 h. Ausführliche Beschreibung