Overexpression of an Inulinase Gene in an Oleaginous Yeast, <b><i>Aureobasidium melanogenum</i></b> P10, for Efficient Lipid Production from Inulin

In this study, in order to directly and efficiently convert inulin into a single-cell oil (SCO), an INU1 gene encoding inulinase from Kluyveromyces marxianus was integrated into the genomic DNA and actively expressed in an SCO producer Aureobasidium melanogenum P10. The transformant API41 obtained produced 28.5 U/mL of inulinase and its wild-type strain P10 yielded only 8.62 U/mL. Most (97.5%) of the inulinase produced by the transformant API41 was secreted into the culture. During a 10-L fermentation, 66.2% (w/w) lipid in the yeast cells of the transformant API41 and 14.38 g/L of cell dry weight were attained from inulin of 80.0 g/L within 120 h, high inulinase activity (23.7 U/mL) was also produced within 72 h, and the added inulin was actively hydrolyzed. This confirmed that the genetically engineered yeast of A. melanogenum P10 is suitable for direct production of lipids from inulin. The lipids produced could be used as feedstocks for biodiesel production.