Effect of two-stage temperature on pullulan production by Aureobasidium pullulans

The effect of a two-stage cultivation temperature on the production of pullulan synthesized by Aureobasidium pullulans CGMCC1234 was investigated. Pullulan production was affected by temperature; although the optimum temperature for pullulan production was 26A degrees C, the optimal temperature for cell growth was 32A degrees C. Maximum pullulan production was achieved by growing A. pullulans in a first stage of 32A degrees C for 2 days, and then in a second stage of 26A degrees C for 2 days. Pullulan production using these two-stage temperatures significantly increased: about 27.80% (w/w) compared to constant-temperature fermentation (26A degrees C for 4 days). The morphology of the A. pullulans (CGMCC 1234) was also affected by temperature; the lower temperature (26A degrees C) supported unicellular biomass growth. Results of this study indicate that fermentation using two temperature stages is a promising method for pullulan production.