Mutation effects of C2+ ion irradiation on the greasy Nitzschia sp.

• The optimal conditions of C2+ ion irradiation on Nitzschia sp. were discussed.
• Get the “saddle type” survival curve.
• One mutant whose lipid content improved significantly was selected.
• The C2+ ion irradiation didn’t change the algae's morphology and growth rate.

Screening and nurturing algae with high productivity, high lipid content and strong stress resistance are very important in algae industry. In order to increase the lipid content, the Nitzschia sp. was irradiated with a 3 MeV C2+ beam. The sample pretreatment method was optimized to obtain the best mutagenic condition and the survival ratio curve. The positive mutants with a significant improvement in lipid content were screened and their C2+ mutagenic effects were analyzed by comparing the greasiness and growth characteristics with the wild type algae. Results showed that when the Nitzschia sp. was cultivated in nutritious medium containing 10% glycerol solution, and dried on the filter for 5 min after centrifugation, the realization of the microalgae heavy ion mutagenesis could be done. The survival ratio curve caused by C2+ irradiation was proved to be “saddle-shaped”. A positive mutant was screened among 20 survivals after irradiation, the average lipid content of the mutation increased by 9.8% than the wild type after 4 generations. But the growth rate of the screened mutation didn’t change after the heavy ion implantation compared to the wild type algae.