Direct conversion of inulin into single cell protein by the engineered Yarrowia lipolytica carrying inulinase gene

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 yeast Yarrowia lipolytica with high content of protein. The activity of the secreted inulinase was found to be 43.1 ± 0.9 U/ml after cell growth for 80 h. When the engineered yeast cells were grown in the medium containing 4.0% inulin in 2-l fermentor, crude protein in the cells and cell mass could reach 47.5% and 20.1 g/l, respectively within 72 h. Furthermore, when the engineered yeast cells were grown in the medium containing 8.0% the meal of Jerusalem artichoke tuber in 2-l fermentor, crude protein and cell mass could reach 53.7% and 20.8 g/l, respectively within 80 h. Therefore, the engineered Y. lipolytica could be further used to produce single cell protein from inulin and inulin-containing materials.