Li, YantaoRamarui, KyariiRamarui, Kyarii2021-09-012021-09-012019-01-0112094http://hdl.handle.net/11603/22908Astaxanthin is a keto-carotenoid known for its strong antioxidant activity. It is widely used in the aquaculture and nutraceutical industries. Haematococcus pluvialis has long been used as a natural source of astaxanthin, however, its slow growth rate creates a production bottleneck. To overcome this bottleneck, Haematococcus mutants with improved growth rate under heterotrophic culture conditions were generated. This was achieved through screening for mutants with improved acetate catabolic rates. An ethyl methanesulfonate based chemical mutagenesis approach was used to generate Haematococcus mutants. Two mutants, YLEMS 3L-33 and KREMS 23D-3, were identified after three rounds of screening, which showed 75% and 21% higher biomass concentrations than the wild type under heterotrophic growth conditions, respectively. Interestingly, when grown under high light to induce astaxanthin biosyntheses, the biomass concentrations of YLEMS 3L-33 and KREMS 23D-3 were 46% and 65% higher than the wild type, respectively. It was hypothesized that these mutants may exhibit a higher acetate catabolism rate under heterotrophic conditions. Acetate metabolism produces acetyl-CoA, which is an integral intermediate in various biosynthetic pathways related to growth and astaxanthin biosyntheses. Therefore, the acetate consumption rate, lipid content, and astaxanthin content of YLEMS 3L-33 and KREMS 23D-3 mutants were comparatively analyzed against the wild type. Our data showed the acetate consumption rate in both mutants was about 60% higher than the wild type. Additionally, the final astaxanthin contents of YLEMS 3L-33 and KREMS 23D-3 were 86% and 66% higher than the wild type, respectively. The astaxanthin productivities of both mutants were about 2.7-fold higher than the wild type.application:pdfAstaxanthinChemical mutagenesisHaematococcus pluvialisHeterotrophicText