TECHNOLOGY FOCUS - BIOTECHNOLOGY - Preparation (claimed): The mutagenic strain is produced by (a) obtaining D.tertiolecta wild strain as starting strain, and inoculating the wild strain in culture medium to culture at an illumination incubator, (b) subjecting the cultured wild strain culture to mutagenesis and treating using ethyl methanesulfonate with a certain concentration, (c) culturing treated strain under normal culture prerequisite to grow single algae, picking single algae and preserving at a plane plate to obtain mutagenesis strain, (d) screening abundant mutagenesis strain based on growth rate, and providing stable expression of excellent properties through multistep and grade screening, and (e) further screening selected mutagenesis strain with fast growth, and providing stable expression of excellent properties through multistep screening. Preferred Microorganism: The wild strain culture used for mutagenesis treatment is at logarithmic phase.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Components: The culture medium is Erdschreiber's medium (EM) culture medium. The cell culture plate is cell culture plate with 12 wells. Preferred Method: The normal culture prerequisite is to culture at 25 degrees C, 4000 lux, for 12 hours in light (L)/12 hours in darkness (D) in an illumination incubator. The mutagenesis treatment method of ethyl methanesulfonate, involves obtaining strain at logarithmic phase to centrifuge and concentrate, adding EMS working solution with equal volume of 2% concentration, treating for 45 minutes and then stopping reacting, centrifuging to remove EMS liquid, adding fresh EM culture medium, and culturing under normal culture prerequisite for one week, where the normal culture prerequisite is to culture at 25 degrees C, 4000 lux for 12 hours L/12 hours D in the illumination incubator. The method involves testing optical density (OD)750 value of cultured strain liquid, diluting to a certain concentration, and painting solid EM culture medium plane plate to obtain single strain. The step of initial screening is picking single strain from original preservation plane plate, culturing and activating through solid culture medium, separately inoculating in liquid culture medium, culturing through two generations cell culture plates and two generations diaphanous glass vessels, adjusting the same inoculation concentration during transfer of culture, and breeding by strain with fast growth under normal culture prerequisite, where the normal culture prerequisite is to culture at 25 degrees C, 4000 lux for 12 hours L/12 hours D in the illumination incubator. The screening further involves picking strain with high growth speed ensured by initial screening from original preservation plane plate, culturing and activating through solid culture medium, separately inoculating in liquid culture medium, transferring of culture through three generations in diaphanous glass vessels, and breeding by grades and ensuring strain with high growth rate.