Increased production of pullulan in Aureobasidium pullulans YQ65 through reduction of intracellular glycogen content

Abstract

Environmental pH is an important parameter that impacts the growth, reproduction, and carbohydrate metabolism of Aureobasidium spp.. This study identifies the ApGph1 gene (encoded with Glycogen Phosphatase) reflecting significant carbohydrate metabolism difference through transcriptome analysis of Aureobasidium Pullulans YQ65 cultured under different pH. It is subsequently analyzed using the Conserved Domains and Expasy tools. It has been found that compared with its wild type, the △ApGph1 strain exhibits no significant differences in its growth pattern and morphology but a production volume of pullulan inversely proportional to its glycogen content. In addition, through fed-batch fermentation, an over-expressed ApGph1 strain can produce 42.7 g/L of pullulan within 144 h, which is related to the increased expression of key genes involved in pullulan synthesis. The results can provide a guide for the industrial production of pullulan.