Comparative Assessment of Pullulan Production by Aureobasidium pullulans under Fed-Batch and Continuous Fermentation

PULLULAN production was studied in bioreactor under fed-batch ….. and continuous cultures conditions by Aureobasidium pullulans ATCC 42023. In fed batch culture, sugar feeding according to consumption rate was the best strategy for pullulan production where it recorded higher pullulan yield than pulsed and continuous sugar feeding. The maximum amount of pullulan concentration was obtained by using sugar feeding according to sugar consumption rate being 88.8 gl-1, after 144 h followed by continuous culture technique at 0.03 h-1 dilution rate, being 86.16 gl-1 after 96 h of incubation at 28ºC. Continuous culture at 0.03 h-1 dilution rate, 5.5 pH controlled, aeration rate of 1.0 vvm air and agitation rate of 700 rpm, attained the highest productivity of pullulan being 0.896 gl-1h-1. Therefore, continuous culture technique with the dilution rate 0.03 h-1 was the most efficient for pullulan production as it increased pullulan formation by 1.5 fold compared with fed-batch culture. There was no remarkable difference between using different solvents for pullulan precipitation on the final concentrations. Produced pullulan gave close physical properties to standard pullulan.