Abstract: The content changes of proline and soluble sugar in two Antarctic ice microalgae under low temperature stress were measured and analyzed for understanding their cold-adaptation mechanisms.Measuring the proline and soluble sugar in two microalgae at different low temperatures and culturing time, the changing trend of them with the temperature and stress time at low temperature was obtained, and the reasons of it was analyzed.The lower the temperature was, the more significantly the contents of proline and soluble sugar in Pyramidomonas sp.L-1 increased.The amount of proline was 6.5 times of initial one and the soluble sugar increased 60% after 48 h at -5℃.The content of proline in Chlamydomonas sp.L-4 was in the same way as Pyramidomonas sp.L-1, i.e., the lower the temperature was, the higher the content of proline was.However, the changing trend of the content with the time was in contrast, decreasing with the culturing time.The proline was almost unchanged after 48 hours at -5℃, while soluble sugar increased 1.9 times.In conclusion, proline and soluble sugar play an important role in the cold-adaptation mechanism of Antarctic ice microalgae, however, the action mechanism is different in the different algae species.

Key words: Antarctic ice microalgae, cold-adaptability, proline, soluble sugar