Development of a Strategy to Improve the Stability of Culture Environment for Docosahexaenoic Acid Fermentation by Schiz
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Development of a Strategy to Improve the Stability of Culture Environment for Docosahexaenoic Acid Fermentation by Schizochytrium sp. Dong-Sheng Guo 1 & Ling-Ling Tong 1 & Xiao-Jun Ji 2 & Lu-Jing Ren 2 & Qing-Qing Ding 3 Received: 7 January 2020 / Accepted: 12 March 2020/ # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
A stable culture environment is the key for optimal growth and metabolic activity of microorganisms, especially in marine species, and intermittent feeding during DHA production using Schizochytrium sp. generates an unstable culture environment. To investigate the effect of unstable culture environment on the cells’ physiological status and DHA synthesis, fermentations with different feeding strategies were performed on the lab scale. The intermittent feeding strategy caused fluctuations of substrate concentration and osmotic pressure, which had a negative effect on cell division and product synthesis. The physiological status and metabolic level of Schizochytrium sp. were relatively stable under a continuous feeding strategy with a relatively stable substrate concentration of 20–25 g/L, which was beneficial for the efficient transformation of substrate, leading to an improvement of DHA productivity. This strategy was further applied to pilot scale, whereby the DHA content, DHA productivity, convert ratio of glucose to lipid and DHA reached 55.02%, 320.17 mg/(L·h), 24.35%, and 13.40%, respectively. This study therefore provides an efficient strategy for ensuring a stable culture environment for the production of DHA and similar metabolites.
Keywords Docosahexaenoic acid . Schizochytrium sp. . Feeding strategy . Culture environment
Highlights • Intermittent feeding caused fluctuation of substrate content and osmotic stress. • The Physiological of Schizochytrium sp in unstable culture environment was studied. • Fatty acid metabolism in Schizochytrium sp at different osmotic stress was studied. • The DHA efficient production was realized by a continuous feeding strategy.
* Qing-Qing Ding [email protected] Extended author information available on the last page of the article
Applied Biochemistry and Biotechnology
Introduction Long-chain polyunsaturated fatty acids (LC-PUFAs) are critical components of the plasma membrane and play significant roles in improving physiological functions of humans [1–3]. Especially docosahexaenoic acid (DHA, C22:6), which is the most representative omega-3 LC-PUFA, has received worldwide attention due to its health benefits to both infants and adults [4, 5]. There have been many clinical studies on DHA supplementation, which showed that this LC-PUFA is important for the normal development of the visual and nervous system tissues in infants and young children, while also reducing the risk of cardiovascular disease, alleviating depressive symptoms, and contributing to immune function in adults [6, 7]. Consequently, DHA is widely used as a dietary health supplement. Marine fish used to be the main source of DHA, but the safety, availab
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