Enhancement of astaxanthin production from Haematococcus pluvialis mutants by three-stage mutagenesis breeding

- The content of astaxanthin from Haematococcus pluvialis reached 47.21 ± 3.30 mg/g, which was 1.7 folds as much as that of the wild type.
- Three-stage mutagenesis breeding was proposed and another two superiorities were obtained including high biomass and high activity.
- Diphenylamine was employed in solid agar plated instead of liquid medium.
- The contravariant cultivation from red cells to green cells was achieved.
- The utilization efficiency of nitrogen was considered as one of the indexes for screening.

Haematococcus pluvialis was modified for higher astaxanthin production compatible with the superiorities of high biomass and high activity by three-stage mutagenesis breeding. UV irradiation mutants named UV11-4 made an increase on cell dry weight, but showed a longer growth circle than the wild type. On the basis of UV mutants, ethyl methane sulphonate (EMS) mutants E2-5 cut down the latent phase, brought forward and extended the logarithmic phase. The inhibitor diphenylamine (DPA) was employed to screen high-yield astaxanthin producer by the color change of colonies from green to red on solid medium. Via the contravariant cultivation, proliferation and transformation, the mutant DPA12-2 possessed an 1.7-fold astaxanthin production compared to the wild type, reaching 47.21 ± 3.30 mg/g dry cells.