Effects of organic nitrogen sources on the fermentation of Pullulan by Aureobasidium pullulans

The effect of six organic nitrogen sources on pullulan yield,structure,purity and molecular weight was studied by using Aureobasidium pullulans CGMCC 11062. The results showed that the pullulan yield was different by using different organic nitrogen source,the highest yield was yeast extract,which can reach 60.64 g/L,then was beef extract,peptone,trypton,malt extract and the least was urea.The structure and purity of pullulan by different organic nitrogen species were consistent,which indicated that this strain can be applied to a variety of organic nitrogen to produce pullulan,and it was suitable for industrial production.The molecular weight of produced pullulan under different organic nitrogen was also great difference. The highest molecular weight was the one produced from malt extract,then were beef extract,peptone,trypton,urea and the lowest was yeast. Their weight average molecular weight( Mw) were between 289039 ~ 604375 u,molecular weight distribution was 2.0 ~ 2.4. These studies could provide technical guidance for the different characteristics of pullulan production.