title: Studies on optimization of nitrogen sources for astaxanthin production by Phaffia rhodozyma.
abstract: Fermentation of Phaffia rhodozyma is a major method for producing astaxanthin, an important pigment with industrial and pharmaceutical application. To improve astaxanthin productivity, single factor and mixture design experiments were used to investigate the effects of nitrogen source on Phaffia rhodozyma cultivation and astaxanthin production. Results of single factor experiments showed nitrogen source could significantly affect P. rhodozyma cultivation with respect to carbon source utilization, yeast growth and astaxanthin accumulation. Further studies of mixture design experiments using (NH(4))(2)SO(4), KNO(3) and beef extract as nitrogen sources indicated that the proportion of three nitrogen sources was very important to astaxanthin production. Validation experiments showed that the optimal nitrogen source was composed of 0.28 g/L (NH(4))(2)SO(4), 0.49 g/L KNO(3) and 1.19 g/L beef extract. The kinetic characteristics of batch cultivation were investigated in a 5-L pH-stat fermentor. The maximum amount of biomass and highest astaxanthin yield in terms of volume and in terms of biomass were 7.71 mg/L and 1.00 mg/g, respectively.
authors.affiliation: School of Biosystem Engineering and Food Science, Zhejiang University, Hangzhou 310029, China. nihui@jmu.edu.cn
authors.forename: Hui
authors.initials: H
authors.lastname: Ni
authors.forename: Qi-he
authors.initials: QH
authors.lastname: Chen
authors.forename: Hui
authors.initials: H
authors.lastname: Ruan
authors.forename: Yuan-fan
authors.initials: YF
authors.lastname: Yang
authors.forename: Li-jun
authors.initials: LJ
authors.lastname: Li
authors.forename: Guang-bin
authors.initials: GB
authors.lastname: Wu
authors.forename: Yang
authors.initials: Y
authors.lastname: Hu
authors.forename: Guo-qing
authors.initials: GQ
authors.lastname: He
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D018929:Cell Culture Techniques / Q000379:methods*; D049109:Cell Proliferation; D003198:Computer Simulation; D003904:Mitosporic Fungi / Q000502:physiology*; D008954:Models, Biological; D009584:Nitrogen / Q000378:metabolism*; D024341:Xanthophylls / Q000096:biosynthesis
chemical_list: D024341:Xanthophylls; C005948:astaxanthine; D009584:Nitrogen