Regulation of lipid accumulation in <i>Schizochytrium</i> sp. ATCC 20888 in response to different nitrogen sources

Jiang, Xin; Zeng, Jia; Zhao, Jing; Gao, Zhuo; Zhang, Chunzhi; Chen, Ming

doi:10.1002/ejlt.201700025

Cited by 35 publications

(20 citation statements)

References 23 publications

(52 reference statements)

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“…[5,6] As a consequence, there is now a growing global market for DHA. [7] The traditional source of DHA is marine fish oil, [8] but this product is in limited supply due to declining fish stocks, and it may have an undesired fishy smell. [9,10] In addition, fish oil has a poor oxidative stability and may not always be free of pollutants, so that alternative sources of DHA are wanted.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Inulin as a Promising Alternative Feedstock for Docosahexaenoic Acid Production by Schizochytrium sp. ATCC 20888

Dai

Zhao

Cheng

et al. 2020

Euro J Lipid Sci & Tech

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Schizochytrium sp. is considered as a promising alternative commercial source of docosahexaenoic acid (DHA), but the production is hindered by the high feedstock cost. In this study, inulin is used as a cheap and readily available feedstock for Schizochytrium sp. ATCC 20888 to produce DHA. The strain could not utilize inulin directly and therefore inulin first needed to be hydrolyzed. Compared with the acidic hydrolyzate by HCl and hydrolyzate by endo‐inulinase, the hydrolyzate by exo‐inulinase serves as the most effective carbon source for microalgal growth. Hydrolysis of inulin by exo‐inulinase is further optimized, and up to 97.8% of inulin conversion is obtained under the optimal conditions of 40 °C, pH 7.0, substrate concentration of 80 g L−1 and exo‐inulinase loading of 2 g kg−1 substrate for 12 h. The resulting hydrolyzate containing mainly fructose is used for the DHA production by the microalga. The lipid content in biomass, DHA content in total fatty acids, DHA yield, and DHA productivity at 72 h reach 45.26%, 35.59%, 5.64 g L−1 and 1.88 g L−1 d−1, respectively. The results suggest that inulin is an excellent feedstock for Schizochytrium sp. suitable for commercial DHA production. Practical Applications: DHA is an essential nutrient for human health and is widely used in infant formula and functional food. As a reserve carbohydrate, inulin present in plants represents a cheap, abundant, and readily available bioresource. This study describes the suitability of inulin as a promising alternative to glucose for DHA production by Schizochytrium sp. Hence, a practical bioprocess for commercial DHA production from inulin by Schizochytrium sp. could be developed. As far as it is known, this is the first report of inulin as a feedstock for Schizochytrium sp. to produce DHA.

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Section: Introductionmentioning

confidence: 99%

“…is severely hindered by the high production cost, which decreases the economic competitiveness of the product. [7] To reduce the cost, many efforts have been made to enhance DHA production through optimizing medium composition, [25,26] regulation strategy, [27][28][29] and strains breeding. [23,30,31] Schizochytrium sp.…”

Section: Introductionmentioning

confidence: 99%

Inulin as a Promising Alternative Feedstock for Docosahexaenoic Acid Production by Schizochytrium sp. ATCC 20888

Dai

Zhao

Cheng

et al. 2020

Euro J Lipid Sci & Tech

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“…It is well known that a limited-nitrogen condition induces lipid and DHA synthesis while inhibiting cellular growth in Aurantiochytrium sp. [11,12]. The mechanism of nitrogen regulation (mainly yeast extract and peptone) has been preliminarily illuminated.…”

Section: Introductionmentioning

confidence: 99%

“…The mechanism of nitrogen regulation (mainly yeast extract and peptone) has been preliminarily illuminated. Jiang et al revealed by analyzing the activities of isocitrate dehydrogenase (ICDH) and malic enzyme (ME) that nitrogen exhaustion facilitates lipid and DHA accumulation in Aurantiochytrium sp., which provides the NADPH for fatty acid synthesis [12]. Metabolomic technology and enzymatic activity analysis have been applied to illuminate variations in metabolites and activities of critical enzymes in the metabolic pathways of Aurantiochytrium sp.…”

Section: Introductionmentioning

confidence: 99%

Transcriptome Mechanism of Utilizing Corn Steep Liquor as the Sole Nitrogen Resource for Lipid and DHA Biosynthesis in Marine Oleaginous Protist Aurantiochytrium sp.

Wang

Zhu

et al. 2019

Biomolecules

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In the current study, corn steep liquor (CSL) is evaluated as an ideal raw agro-material for efficient lipid and docosahexaenoic acid DHA production by Aurantiochytrium sp. Low CSL level in medium (nitrogen deficiency) stimulated the biosynthesis of lipids and DHA while inhibiting cellular growth. The transcriptomic profiles of the Aurantiochytrium sp. cells are analyzed and compared when cultured under high (H group), normal (N group), and low (L group) levels of CSL in the medium. The discriminated transcriptomic profiles from the three groups indicates that changes in CSL level in medium result in a global change in transcriptome of Aurantiochytrium sp. The overall de novo assembly of cDNA sequence data generated 61,163 unigenes, and 18,129 of them were annotated in at least one database. A total of 5105 differently expressed (DE) genes were found in the N group versus the H group, with 2218 downregulated and 2887 upregulated. A total of 3625 DE genes were found in the N group versus the L group, with 1904 downregulated and 1721 upregulated. The analysis and categorization of the DE genes indicates that the regulation mechanism of CSL involved in the perception and transduction of the limited nitrogen signal, the interactions between the transcription factors (TFs) and multiple downstream genes, and the variations in downstream genes and metabolites, in sequence, are illuminated for the first time in the current study.

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“…Much work focused on the thraustochytrid culture optimization demonstrated significant improvements in their biomass and DHA yields ( Chen et al, 2016 , Jiang et al, 2017 , Ludevese-Pascual et al, 2016 , Lung et al, 2016 , Patil and Gogate, 2015 , Zhao et al, 2017 , Zhu et al, 2008 ). The biomass can reach up to 171.5 g/L under the optimal cultivation condition ( Bailey et al, 2003 ), and with modified medium the total fatty acids (TFA) could account for 83.84% of biomass ( Li et al, 2015 ) with PUFA content as high as 76.5% ( Marchan et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

Alleviation of reactive oxygen species enhances PUFA accumulation in Schizochytrium sp. through regulating genes involved in lipid metabolism

Zhang

Sen

et al. 2018

Metabolic Engineering Communications

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The unicellular heterotrophic thraustochytrids are attractive candidates for commercial polyunsaturated fatty acids (PUFA) production. However, the reactive oxygen species (ROS) generated in their aerobic fermentation process often limits their PUFA titer. Yet, the specific mechanisms of ROS involvement in the crosstalk between oxidative stress and intracellular lipid synthesis remain poorly described. Metabolic engineering to improve the PUFA yield in thraustochytrids without compromising growth is an important aspect of economic feasibility. To fill this gap, we overexpressed the antioxidative gene superoxide dismutase (SOD1) by integrating it into the genome of thraustochytrid Schizochytrium sp. PKU#Mn4 using a novel genetic transformation system. This study reports the ROS alleviation, enhanced PUFA production and transcriptome changes resulting from the SOD1 overexpression. SOD1 activity in the recombinant improved by 5.2–71.6% along with 7.8–38.5% decline in ROS during the fermentation process. Interestingly, the total antioxidant capacity in the recombinant remained higher than wild-type and above zero in the entire process. Although lipid profile was similar to that of wild-type, the concentrations of major fatty acids in the recombinant were significantly (p ≤ 0.05) higher. The PUFA titer increased up to 1232 ± 41 mg/L, which was 32.9% higher (p ≤ 0.001) than the wild type. Transcriptome analysis revealed strong downregulation of genes potentially involved in β-oxidation of fatty acids in peroxisome and upregulation of genes catalyzing lipid biosynthesis. Our results enrich the knowledge on stress-induced PUFA biosynthesis and the putative role of ROS in the regulation of lipid metabolism in oleaginous thraustochytrids. This study provides a new and alternate strategy for cost-effective industrial fermentation of PUFA.

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

Cited by 35 publications

References 23 publications

Inulin as a Promising Alternative Feedstock for Docosahexaenoic Acid Production by Schizochytrium sp. ATCC 20888

Inulin as a Promising Alternative Feedstock for Docosahexaenoic Acid Production by Schizochytrium sp. ATCC 20888

Transcriptome Mechanism of Utilizing Corn Steep Liquor as the Sole Nitrogen Resource for Lipid and DHA Biosynthesis in Marine Oleaginous Protist Aurantiochytrium sp.

Alleviation of reactive oxygen species enhances PUFA accumulation in Schizochytrium sp. through regulating genes involved in lipid metabolism

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