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