Phaffia rhodozyma cultivation on structural and non-structural sugars from sweet sorghum for astaxanthin generation

摘要

Sweet sorghum contains non-structural and structural sugars that can be converted to co-products in biorefinery processes. Astaxanthin is one such co-product that can be produced through fermentation with the yeast strain Phaffia rhodozyma and utilized in high value market applications such as aquaculture feed. This work investigated P. rhodozyma cultivation in sweet sorghum juice (SSJ) with increased nitrogen supplementation and supplemented sweet sorghum bagasse (SSB) hydrolysate to determine biomass growth and carotenoid production. Batch bioreactor fermentation on SSJ with ammonium sulfate supplementation produced 34.9 g/L biomass with 53.3 mg/L astaxanthin at a productivity of 0.352 mg/L/h after 168 h of cultivation. Alternatively, supplemented SSB hydrolysate was found to be an inadequate media for P. rhodozyma cultivation likely due to inhibition by phenolic compounds. Improved biomass growth and carotenoid production occurred after activated carbon (AC) detoxification by generating 23.6 g/L biomass and 48.89 mg/L astaxanthin at a productivity of 0.291 mg/L/h.