Expression of inulinase gene in the oleaginous yeast Yarrowia lipolytica and single cell oil production from inulin-containingmaterials

Yarrowia lipolytica ACA-DC 50109 has been reported to be an oleaginous yeast and significant quantities of lipids were accumulated inside the yeast cells. In this study, the INU1 gene encoding exo-inulinase cloned from Kluyveromyces marxianus CBS 6556 was ligated into the expression plasmid pINA1317 and expressed in the cells of the oleaginous yeast. The activity of the inulinase with 6×His tag secreted by the transformant Z31 obtained was found to be 41.7 U mL−1 after cell growth for 78 h. After optimization of the medium and cultivation conditions for single cell oil production, the transformant could accumulate 46.3% (w/w) oil from inulin in its cells and cell dry weight was 11.6 g L−1 within 78 h at the flask level. During the 2-L fermentation, the transformant could accumulate 48.3% (w/w) oil from inulin in its cells and cell dry weight was 13.3 g L−1 within 78 h while the transformant could accumulate 50.6% (w/w) oil from extract of Jerusalem artichoke tubers in its cells and cell dry weight was 14.6 g L−1 within 78 h. At the end of fermentation, most of the added sugar was utilized by the transformant cells. Over 91.5% of the fatty acids from the transformant cultivated in the extract of Jerusalem artichoke tubercles was C16:0, C18:1 and C18:2, especially C18:1 (58.5%).