High-cell-density cultivation of Schizochytrium sp. in an ammonium/pH-auxostat fed-batch system

• Published in: Biotechnology letters 2008-09, Vol.30 (9), p.1559-1564
• Main Authors: Ganuza, E, Anderson, A. J, Ratledge, C
• Format: Article
• Language: English
• Subjects: Ammonia; Ammonium; Applied Microbiology; Biochemistry; Biological and medical sciences; Biomedical and Life Sciences; Bioreactors; Biotechnology; Cell Count; Cell Culture Techniques - methods; Cells; Cultivation; Eukaryota - cytology; Eukaryota - drug effects; Eukaryota - growth & development; Fatty Acids - analysis; Fermentation; Fermentation - drug effects; Fundamental and applied biological sciences. Psychology; Glucose - pharmacology; Hydrogen-Ion Concentration - drug effects; Life Sciences; Microbiology; Microorganisms; Original Research Paper; Polyunsaturated fatty acids; Quaternary Ammonium Compounds - pharmacology; Schizochytrium; Studies; Sugar
• ISSN: 0141-5492; 1573-6776
• DOI: 10.1007/s10529-008-9723-4

Thraustochytrids, in particular Schizochytrium spp., are used for the production of the valuable polyunsaturated fatty acid, docosahexaenoic acid (DHA; 22:6 n-3). Growth of Schizochytrium sp. G13/2S in a defined medium was initially made in shake-flask cultures to determine the optimum concentrations of glucose (100-200 g l⁻¹) and ammonia (~300 mg l⁻¹) that could be used by this microorganism. In subsequent fermenter cultures, a pH-auxostat method was used to maintain NH₃ from 200-300 mg l⁻¹. During the first 49 h of fermentation, 150 g glucose l⁻¹ produced 63 g cell dry wt l⁻¹. Although growth was not limited by the supply of nitrogen, total fatty acids were at 25% cell dry wt which is more than half the final lipid content of commercially-grown Schizochytrium biomass which uses N-limited medium in the final stages for maximum lipid accumulation. This strategy is therefore useful for the cultivation of Schizochytrium to a high cell density up to the point when lipid accumulation can be triggered by N exhaustion.