Oxygen transfer coefficient and the kinetic parameters of exo-polygalacturonase production by Aspergillus flavipes FP-500 in shake flasks and bioreactor

Aims: To evaluate and compare the sensitivity of Exo-PG production and kinetic parameters of Aspergillus flavipes FP-500 to oxygen transfer condition in shake flasks and bioreactor. Methods and Results: Aspergillus flavipes FP-500 was grown on pectin as carbon source in shake flasks and bioreactor at different oxygen transfer conditions. The volumetric coefficient of oxygen transfer (k(L)a) was modified by changing both, the flask size/medium volume ratio and the agitation speed. Higher biomass concentration, Exo-PG activity, maximum specific growth rate and yield coefficient were obtained in bioreactor at higher k(L)a value. A strong correlation was found between biomass, Exo-PG activity and growth-associated product coefficient to kLa in bioreactor but does not in shake flasks. The mathematical model provided a good description of growth, pectin consumption and Exo-PG production in submerged batch cultures carried out in bioreactor. Conclusions: Biomass concentration, Exo-PG activity and their kinetics of Aspergillus flavipes FP-500 were strongly influenced by oxygen transfer condition and cultivation system. Significance and Impact of Study: The production of enzymes by fungal fermentation is strictly aerobic and understanding the influence of oxygen transfer condition on the production kinetic is of vital importance in order to design, optimize and translate bioprocesses to industrial scale.