Genome sequencing of Aureobasidium pullulans P25 and overexpression of a glucose oxidase gene for hyper-production of Ca-gluconic acid.

Gluconic acid (GA) has many applications such as in the food and pharmaceutical industry. Aureobasidium pullulans P25 strain is able to produce high levels of Ca-GA. The genome length, GC content and the gene number of this yeast were found to be 30.97 Mb, 50.28% and 10,922, respectively. The pathways for gluconic acid biosynthesis were annotated. Glucose oxidase (Gox) sequences from different strains of A. pullulans were highly similar but were distinct from those of other fungi. The glucose oxidase had two FAD binding sites and a signal sequence. Deletion of the GOX gene resulted in a strain that showed no Gox activity and that was unable to produce Ca-GA. Overexpression of the GOX gene in strain P25 generated strain GA-6 that produced 200.2 ± 2.3 Ca-GA g/l and 2480 U/mg of Gox activity. The productivity of Ca-GA was 2.78 g/l/h and the yield was 1.1 g/g.