Abstract: To obtain a better culture conditions for microalgae, singlefactor test was performed to reveal the effects of ecological factors on Phaeodactylum tricornutum mutant MP-2, including temperature (10, 15, 20, 25, 30 ℃), light intensity (20, 40, 60, 80, 100, 120 μmol·m^-2·s^-1) and salinity (5, 10, 15, 20, 25, 30, 35, 40). The results showed that all these ecological factors exerted significant effects on the growth, total lipid content and fatty acid composition of MP-2. This strain would get a better growth and higher lipid content at 10-25 ℃, and the optimal temperature is 20 ℃. The highest contents of EPA and PUFA appeared at 15 ℃, because low temperature was favorable to their accumulation. The suitable light intensity for growth was defined at 20-120 μmol·m^-2·s^-1, with the optimum at 40 μmol·m^-2·s^-1. Low light intensity benefits the accumulation of total lipid, with highest total lipid content at 20-40 μmol·m^-2·s^-1. The light intensity also had a significant effect on the accumulation of EPA and PUFA (P<0.05), with highest contents of EPA (29.15%) and PUFA (40.22%-40.56%) at 100 μmol·m^-2·s^-1 and 80-100 μmol·m^-2·s^-1, respectively. This strain would grow well at salinities 10-40, with optimum at 25. High salinity would be beneficial to total lipid content, whilst low salinity would be beneficial to the accumulations of EPA and PUFA. The highest total lipid content would be obtained at salinities 30-35, while EPA and PUFA at salinities 10-15 and 15, respectively.

Key words: landscaping trees, leaf surface morphology, PM₂₅, atomic force microscopy (AFM), adsorption ability