Method for producing Pulullans with different molecular weights

The invention belongs to the field of microbial fermentation, and particularly relates to a method for producing Pulullans with different molecular weights by fermenting Aureobasidium pullulans. The method comprises the following steps: (1) preparing an Aureobasidium pullulans seed solution; and (2) inoculating the seed solution to a fermentation medium, and fermenting to produce the Pulullans, wherein the Pulullans with different molecular weights are produced by changing the K2HPO4 content in the fermentation medium and controlling the pH value of the fermentation liquid in the fermentation process. The control range of the K2HPO4 content is 1-7 g/L, and the control range of the pH value is 3.0-4.0.By changing the dipotassium hydrogen phosphate content in the fermentation medium and combining the pH value control in the fermentation process, the enzyme activity in the Pulullan synthesis and degradation process is influenced, thereby obtaining the Pulullans with different molecular weights. Thus, the Pulullans can be widely and reasonably used in the fields of food, medicine, chemical engineering and petroleum, thereby further satisfying the demands of people.