SJ was rich in carbohydrate, including sucrose as well as fructose and glucose. The contents of sucrose, fructose and glucose in SJ applied in this study were 101.7, 33.1 and 25.0 g L−1, respectively. Cell growth and lipid accumulation of heterotrophic C. protothecoides with different sugars as carbon source were shown in Fig. 1. At 120 h, cell density of C. protothecoides was 3.7, 3.9 and 1.2 g L−1 in culture medium with the initial concentration of 10 g L−1 of glucose, fructose or sucrose, respectively. And the corresponding lipid content was 53.3%, 52.7% and 37.7% of cell dry weight. The biomass density and lipid content of cells cultured with glucose and fructose showed no significant differences, but these values of cells cultured with sucrose were much lower. The data suggested that sucrose, which accounted for 63.6% of the total sugar in sweet sorghum juice, can not be utilized by heterotrophic C. protothecoides without hydrolysis. Thus, in order to convert SJ to biodiesel through the cultivation of C. protothecoides in high efficiency, sucrose in SJ should be hydrolyzed to glucose and fructose prior to use.