Abstract:Both autotrophically and heterotrophically grown Chlorella protothecoides cells have been obtained in cell cultures. The content of liposoluble compounds in the cells of heterotrophic algae occupied 72% of the total cells in dry weight, which was more than 4 times as high as that in the autotrophic algal cells. There existed remarkbly different distribution patterns of the hydrocarbons in thesetwo kinds of cells. The hydrocarbons in autotrophic cells were characterised by the predominance of C17 normal alkanes, wheraes the heterotrophic cells were rich in normal alkanes of higher molecular weight or longer carbon chain with C25 as the dominant carbon. The structure of the compounds in benzene fraction is not quite clear, but the compounds in autotrophis sample may be related to the degeneration of the pigments. The compounds in heterotrophic sample probably come from lipid acids. The visible--ultraviolet absorption spectrum of the pigment compounds demonstrated the absorption peaks of the acetone extract from the autotrophic cells at 432.5, 451.5, 472.5 and 661.5 nm, reflecting the existence of chlorophyll and carotenoid, both with a rather high concentration. However, the acetone extract from the hetertrophic algal cells only showed absorption peaks at 427.4, 450.8 and 477.5 nm. The absorption peaks of the original green cells completely disappeared at 432.5 and 661.5 nm, reflecting the disappearance of chlorophyll in cells on the whole; the remaining absorption peaks only reflected the existence of carotenoid, but its concentration had already been greatly reduced. The resuls from comparative experiments were of essential significance on the study of physiological metabolism in heterotrophically grown C. protothecoides and on the exploration and application of the lipid compounds in this kind of algae.