Regulation of lipid accumulation in Schizochytrium sp. ATCC 20888 in response to different nitrogen sources

Summary

Regulation of lipid accumulation in Schizochytrium sp. ATCC 20888 in response to different nitrogen sources was investigated in this study. Nitrogen sources had important effects on the cell growth, lipid accumulation and docosahexaenoic acid (DHA) percentage in total fatty acids (TFAs). Compared with sole organic nitrogen source, the combination of yeast extract and ºmonosodium glutamate (MSG) greatly enhanced the biomass, total lipids and DHA percentage in TFAs, but inorganic nitrogen source addition decreased the biomass and total lipids. The results showed that lipids began to accumulate rapidly with the depletion of dissolved ammonia in broth, and the time required for nitrogen exhaustion was extended with increasing nitrogen source concentration. Furthermore, the analysis of isocitrate dehydrogenase (ICDH) and malic enzyme (ME) activities during fermentation process provided insight for the revelation of regulation mechanism of lipid accumulation in Schizochytrium sp. ATCC 20888 in response to nitrogen exhaustion in broth.

Practical applications: DHA, an essential nutrient for human health, is widely used in infant formula and functional foods. DHA production by Schizochytrium sp. has recently received extensive attention as the commercial source of DHA to substitute marine fish oil. Nitrogen sources in the cultivation of Schizochytrium sp. have important effects on the cell growth, lipid accumulation and DHA percentage in TFAs. This study provides valuable guidance for nitrogen source selection for efficient DHA-rich lipids production by Schizochytrium sp.

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