title: Improved docosahexaenoic acid production in Aurantiochytrium by glucose limited pH-auxostat fed-batch cultivation.
abstract: Fed-batch, pH auxostat cultivation of the docosahexaenoic acid (DHA)-producing microorganism Aurantiochytrium B072 was performed to obtain high cell density and record high productivity of both total fatty acid (TFA) and DHA. Using glucose feeding by carbon excess (C-excess) and by C-limitation at various feeding rates (70%, 50% or 20% of C-excess), high biomass density was obtained and DHA/TFA content (w/w) was improved from 30% to 37% with a 50% glucose feed rate when compared with C-excess. To understand the biochemistry behind these improvements, lipogenic enzyme assays and in silico metabolic flux calculations were used and revealed that enzyme activity and C-fluxes to TFA were reduced with C-limited feeding but that the carbon flux to the polyketide synthase pathway increased relative to the fatty acid synthase pathway. As a result, a new strategy to improve the DHA to TFA content while maintaining relatively high DHA productivity is proposed.
authors: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors: Panyawut
authors: P
authors: Janthanomsuk
authors: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand.
authors: Cornelis
authors: C
authors: Verduyn
authors: Department of Biotechnology, Faculty of Science, Mahidol University, Bangkok 10400, Thailand. Electronic address: somchai.cha@mahidol.ac.th.
authors: Somchai
authors: S
authors: Chauvatcharin
mesh_terms: D018533:Biomass; D019149:Bioreactors; D002244:Carbon / Q000378:metabolism; D004281:Docosahexaenoic Acids / Q000032:analysis / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D058009:Stramenopiles / Q000378:metabolism*
chemical_list: D004281:Docosahexaenoic Acids; D002244:Carbon; D005947:Glucose
keywords: Aurantiochytrium B072; Carbon-limited feeding; Docosahexaenoic acid; Lipogenic enzymes; pH-auxostat fed-batch cultivation