Fed‐batch fermentation of Phaffia rhodozyma D3 for enhanced astaxanthin production and nutritional components analysis

BACKGROUND Astaxanthin is a high‐value ketocarotenoid with excellent antioxidant properties, anti‐tumor and immune‐enhancing properties, which has a broad development prospect in the food, feed, medical and nutraceutical industries. Currently, Phaffia rhodozyma is a promising source for natural astaxanthin. The study adopted a fed‐batch fermentation strategy to improve the astaxanthin production and determine the nutrient composition of the P. rhodozyma D3 culture. RESULTS The results showed that the optimal fed‐batch fermentation was a two‐stage carbon/nitrogen (C/N) fed‐batch fermentation. The astaxanthin content was 5.386 mg/g, 1.27 times that of batch fermentation. The nutrient composition of the P. rhodozyma D3 culture was also determined by high‐performance liquid chromatography (HPLC) and gas chromatography (GC). It revealed a composition rich in astaxanthin, proteins, lipids, minerals, and unsaturated fatty acids, complying with feed additive regulations established by the US Food and Drug Administration (FDA), the European Commission, and China's Ministry of Agriculture and Rural Affairs. The crude protein, total sugars, crude fat and crude fiber content of the culture were 34.8%, 31.5%, 9.6%, and 1.4%, respectively. Fatty acids were mainly oleic acid and linoleic acid, glutamate and aspartic acids were the main amino acids with contents of 33.16 and 31.36 mg/g, respectively. CONCLUSION It demonstrated that the fed‐batch fermentation strategy promoted astaxanthin production and that P. rhodozyma contains numerous nutritional ingredients, which can potentially serve as high‐value functional components in animal feed formulations.