Pullulan biosynthesis and its regulation in Aureobasidium spp.

It has been well known that different strains of Aureobasidium spp. can yield a large amount of pullulan. Although pullulan has wide applications in various sectors of biotechnology, its biosynthesis and regulation were not resolved. Lately, the molecular mechanisms of pullulan biosynthesis and regulation have been elucidated and their genes and encoding proteins have been identified using the genome-wide mutant analysis. It is found that a multidomain AmAgs2 is the key enzyme for pullulan biosynthesis and the alternative primers are required for its biosynthesis. Pullulan biosynthesis is regulated by glucose repression and signaling pathways. Elucidation of such a biosynthetic pathway and regulation is of significance in biotechnology. Therefore, the present review article mainly summaries the recent research proceedings in this field, hoping to promote further endeavors on enhanced pullulan production and improved chemical properties of pullulan via molecular modifications of the producers by using synthetic biology approaches.