Transcriptome analysis reveals that up-regulation of the fatty acid synthase gene promotes the accumulation of docosahexaenoic acid in Schizochytrium sp. S056 when glycerol is used

Chen, Wei; Zhou, Pengpeng; Zhang, Meng; Zhu, Yongming; Wang, Xiaopeng; Luo, Xin-an; Bao, Zhendong; Yu, Liang

doi:10.1016/j.algal.2016.02.007

Cited by 60 publications

(27 citation statements)

References 63 publications

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“…HK, encoding a kinase that phosphorylates glucose to glucose-6-phosphate, was downregulated by 7.22-fold under the H condition. In contrast, previous studies have found that using glycerol as a carbon source or culturing under high oxygen supply enhances the expression of HK in Schizochytrium (24,39). As a key enzyme in EMP, PfkA is responsible for catalyzing the ATP-dependent phosphorylation of fructose-6-phosphate to fructose 1,6-bisphosphate.…”

Section: Discussionmentioning

confidence: 74%

Effects of Methanol on Carotenoids as Well as Biomass and Fatty Acid Biosynthesis in Schizochytrium limacinum B4D1

Liao

Gao

et al. 2019

Appl Environ Microbiol

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Schizochytrium is a promising source for the production of docosahexaenoic acid and astaxanthin. The effects of different methanol concentrations on astaxanthin, biomass, and production of the lipids, squalene, and total sterol in Schizochytrium limacinum B4D1 were investigated. Astaxanthin began to accumulate when the methanol concentration reached 3.2% and peaked at 5.6% methanol, with a 2,000-fold increase over that in the control. However, under cultivation with 5.6% methanol, the biomass, lipids, squalene, and total sterol decreased to various degrees. Transcriptomic analysis was performed to explore the effects of different methanol concentrations (0%, 3.2%, and 5.6%) on the expression profile of B4D1. Three key signaling pathways were found to play important roles in regulating cell growth and metabolism under cultivation with methanol. Five central carbon metabolism-associated genes were significantly downregulated in response to 5.6% methanol and thus were expected to result in less ATP and NADPH being available for cell growth and synthesis. High methanol conditions significantly downregulated three genes involved in fatty acid and squalene/sterol precursor biosynthesis but significantly upregulated geranylgeranyl diphosphate synthase, lycopene β-cyclase, and β-carotene 3-hydroxylase, which are involved in astaxanthin synthesis, thus resulting in an increase in the levels of precursors and the final production of astaxanthin. Additionally, the transcriptional levels of three stress response genes were upregulated. This study investigates gene expression profiles in the astaxanthin producer Schizochytrium when grown under various methanol concentrations. These results broaden current knowledge regarding genetic expression and provide important information for promoting astaxanthin biosynthesis in Schizochytrium. IMPORTANCE Schizochytrium strains are usually studied as oil-producing strains, but they can also synthesize other secondary metabolites, such as astaxanthin. In this study, methanol was used as an inducer, and we explored its effects on the production of astaxanthin, a highly valuable substance in Schizochytrium. Methanol induced Schizochytrium to synthesize large amounts of astaxanthin. Transcriptomic analysis was used to investigate the regulation of signaling and metabolic pathways (mainly relative gene expression) in Schizochytrium grown in the presence of various concentrations of methanol. These results contribute to the understanding of the underlying molecular mechanisms and may aid in the future optimization of Schizochytrium for astaxanthin biosynthesis.

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Section: Discussionmentioning

confidence: 74%

Effects of Methanol on Carotenoids as Well as Biomass and Fatty Acid Biosynthesis in Schizochytrium limacinum B4D1

Liao

Gao

et al. 2019

Appl Environ Microbiol

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“…When Schizochytrium was cultured at high oxygen supply condition, HK that catalyzes phosphorylating glucose into glucose-6-phosphate was upregulated by 3.4-fold. Similarly, Chen et al [ 42 ] found glycerol as carbon source could enhance the expression of HK in Schizochytrium. As one of key enzymes in the glycolysis, PFK, is responsible for catalyzing the ATP-dependent phosphorylation of fructose-6-phosphate to form fructose 1, 6-bisphosphate.…”

Section: Discussionmentioning

confidence: 96%

“…However, compared with Δ12 desaturase, the expression of Δ6 desaturase and Δ8 desaturase was relatively low, which indicated that these two enzymes played little role in the fatty acid synthesis. Chen et al [ 42 ] suggested that, when glycerol was the carbon source, the FAS gene upregulation led to a higher DHA concentration in Schizochytrium sp. S056.…”

Section: Discussionmentioning

confidence: 99%

Transcriptome and gene expression analysis of docosahexaenoic acid producer Schizochytrium sp. under different oxygen supply conditions

Ren

et al. 2018

Biotechnol Biofuels

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BackgroundSchizochytrium sp. is a promising strain for the production of docosahexaenoic acid (DHA)-rich oil and biodiesel, and has been widely used in the food additive and bioenergy industries. Oxygen is a particularly important environmental factor for cell growth and DHA synthesis. In general, higher oxygen supply favors lipid accumulation, but could lead to a reduction of the DHA percentage in total fatty acids in Schizochytrium sp. To tackle this problem, it is essential to understand the mechanisms regulating the response of Schizochytrium sp. to oxygen. In this study, we aimed to explore the acclimatization of this DHA producer to different oxygen supply conditions by examining the transcriptome changes.ResultsTwo different fermentation processes, namely normal oxygen supply condition (shift agitation speeds from 400 rpm to 300 rpm) and high oxygen supply condition (constant agitation speeds: 400 rpm), were designed to study how the fermentation characteristics of Schizochytrium sp. HX-308 were affected by different oxygen supply conditions. The results indicated that high oxygen supply condition resulted in 49% and 37.5% improvement in the maximum cell dry weight (CDW) and total lipid concentration, respectively. However, the DHA percentage in total fatty acids decreased to 35%, which was 31.4% lower than that produced by normal oxygen supply condition. Moreover, transcriptome analysis was performed to explore the effect of the oxygen supply condition on genetic expression and metabolism. The results showed that glycolysis and pentose phosphate pathway metabolism-associated genes (hexokinase, phosphofructokinase, fructose-bisphosphate aldolase, glucose-6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase) were substantially upregulated in response to high oxygen supply, resulting in more NADPH was available for Schizochytrium. Specially, high oxygen supply condition also led to genes (Δ6 desaturase, Δ12 desaturase, FAS, ORFA, ORFB, and ORFC) involved in fatty acid biosynthesis upregulation. In addition, a transcriptional upregulation of catalase (CAT) became apparent under high oxygen supply condition, while superoxide dismutase (SOD) and ascorbate peroxidase (APX) were found to be down-regulated.ConclusionsThis study is the first to investigate the differences of gene expression at different levels of oxygen availability in the DHA producer Schizochytrium. The results of transcriptome analyses indicated that high oxygen supply condition resulting in more NADPH and acetyl-CoA production for cell growth and lipid synthesis in Schizochytrium. Δ12 desaturase and ORFC showed higher expression levels at high oxygen supply condition, which might be the key regulators for enhancing fatty acid biosynthesis in the future. These results enrich the current knowledge regarding genetic expression and provide important information to enhance DHA production in Schizochytrium sp.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1250-5) contains supplementary material, whi...

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“…Transcriptome analysis reveals that the up-regulation of the fatty acid synthase gene promotes the accumulation of DHA in Schizochytrium sp. S056 when glycerol is used [24]. Transcriptome and gene expression analysis of DHA producer Aurantiochytrium under low-temperature conditions were conducted by Ma et al [25].…”

Section: Introductionmentioning

confidence: 99%

Comparative Transcriptomic Analysis Uncovers Genes Responsible for the DHA Enhancement in the Mutant Aurantiochytrium sp.

Liu

et al. 2020

Microorganisms

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Docosahexaenoic acid (DHA), a n-3 long-chain polyunsaturated fatty acid, is critical for physiological activities of the human body. Marine eukaryote Aurantiochytrium sp. is considered a promising source for DHA production. Mutational studies have shown that ultraviolet (UV) irradiation (50 W, 30 s) could be utilized as a breeding strategy for obtaining high-yield DHA-producing Aurantiochytrium sp. After UV irradiation (50 W, 30 s), the mutant strain X2 which shows enhanced lipid (1.79-fold, 1417.37 mg/L) and DHA (1.90-fold, 624.93 mg/L) production, was selected from the wild Aurantiochytrium sp. Instead of eicosapentaenoic acid (EPA), 9.07% of docosapentaenoic acid (DPA) was observed in the mutant strain X2. The comparative transcriptomic analysis showed that in both wild type and mutant strain, the fatty acid synthesis (FAS) pathway was incomplete with key desaturases, but genes related to the polyketide synthase (PKS) pathway were observed. Results presented that mRNA expression levels of CoAT, AT, ER, DH, and MT down-regulated in wild type but up-regulated in mutant strain X2, corresponding to the increased intercellular DHA accumulation. These findings indicated that CoAT, AT, ER, DH, and MT can be exploited for high DHA yields in Aurantiochytrium.

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Transcriptome analysis reveals that up-regulation of the fatty acid synthase gene promotes the accumulation of docosahexaenoic acid in Schizochytrium sp. S056 when glycerol is used

Cited by 60 publications

References 63 publications

Effects of Methanol on Carotenoids as Well as Biomass and Fatty Acid Biosynthesis in Schizochytrium limacinum B4D1

Effects of Methanol on Carotenoids as Well as Biomass and Fatty Acid Biosynthesis in Schizochytrium limacinum B4D1

Transcriptome and gene expression analysis of docosahexaenoic acid producer Schizochytrium sp. under different oxygen supply conditions

Comparative Transcriptomic Analysis Uncovers Genes Responsible for the DHA Enhancement in the Mutant Aurantiochytrium sp.

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