Direct conversion of inulin and extract of tubers of Jerusalem artichoke into single cell oil by co-cultures of Rhodotorula mucilaginosa TJY15a and immobilized inulinase-producing yeast cells

In this study, it was found that the immobilized inulinase-producing cells of Pichia guilliermondii M-30 could produce 169.3 U/ml of inulinase activity while the free cells of the same yeast strain only produced 124.3 U/ml of inulinase activity within 48 h. When the immobilized inulinase-producing yeast cells were co-cultivated with the free cells of Rhodotorula mucilaginosa TJY15a, R. mucilaginosa TJY15a could accumulate 53.2% oil from inulin in its cells and cell dry weight reached 12.2 g/l. Under the similar conditions, R. mucilaginosa TJY15a could accumulate 55.4% (w/w) oil from the extract of Jerusalem artichoke tubers in its cells and cell dry weight reached 12.8 g/l within 48 h. When the co-cultures were grown in 2 l fermentor, R. mucilaginosa TJY15a could accumulate 56.6% (w/w) oil from the extract of Jerusalem artichoke tubers in its cells and cell dry weight reached 19.6 g/l within 48 h. Over 90.0% of the fatty acids from the yeast strain TJY15a grown in the extract of Jerusalem artichoke tubers was C_16:0, C_18:1 and C_18:2, especially C_18:1 (50.6%).