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He Huang - One of the best experts on this subject based on the ideXlab platform.
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Integration of lipidomic and transcriptomic profiles reveals novel genes and regulatory mechanisms of Schizochytrium sp. in response to salt stress.
Bioresource Technology, 2019Co-Authors: Jia-yi Jiang, He Huang, Xiao-man Sun, Si-yu Zhu, Yu-ting Zhang, Lujing RenAbstract:In this study, the effects of salt stress on the physiological, lipidomic and transcriptomic profiles of halophilic microalga Schizochytrium sp. were investigated. In general, Schizochytrium sp. could survive under high osmotic fermentation medium containing 30 g/L NaCl, and showed a significant increase in C14:0 percentage in total fatty acids. In lipidomic analysis, C14:0 was specifically enriched in phosphatidylcholine (PC), and membrane phospholipids participated in the salt stress response mostly. Specially, one novel signal lipid N-acylphosphatidylethanolamine (NAPE) (18:0/20:3/14:0) was upregulated significantly. Transcriptomic analysis revealed glycerol-3-phosphate acyltransferase (GPAT) and phospholipase ABHD3 (PLABDH3) were involved in C14:0 metabolism and NAPE biosynthesis. Signalling pathways they mediated were activated as evident by high expression level of Myristoyl-CoA: protein N-myristoyltransferase (NMT) and NAPE-hydrolyzing PLD (NAPE-PLD). This study gives us an insight in specific responses to salt stress in Schizochytrium sp. and provides a considerable proportion of novel genes that could commendably be used for engineering modification.
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Development of a strategy for the production of docosahexaenoic acid by Schizochytrium sp. from cane molasses and algae-residue.
Bioresource Technology, 2018Co-Authors: Feng-wei Yin, Lujing Ren, He Huang, Si-yu Zhu, Dong-sheng Guo, Zhen GaoAbstract:Abstract The aim of this work was to reduce the algae-residue emission and make use of cane molasses as fermentation materials for docosahexaenoic acid (DHA) fermentaion by Schizochytrium sp., which further could cut the cost of DHA production. Algae-residue and cane molasses were respectively used as nitrogen and carbon sources to replace yeast extract and glucose. A significant DHA yield of 18.58 g/L was obtained using algae-residue, while cane molasses could not be used well as sole carbon source due to the presence of undesirable substance. A two-stage culture strategy with glucose followed by pretreated cane molasses as carbon source was developed, resulting in a final DHA yield of 15.22 g/L. This study therefore offers an economical and green strategy for DHA production by Schizochytrium sp.
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Transcriptome and gene expression analysis of docosahexaenoic acid producer Schizochytrium sp. under different oxygen supply conditions.
Biotechnology for Biofuels, 2018Co-Authors: Lujing Ren, Xiao-man Sun, Si-yu Zhu, He HuangAbstract:Schizochytrium 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. Two 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. This 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.
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development of a cooperative two factor adaptive evolution method to enhance lipid production and prevent lipid peroxidation in Schizochytrium sp
Biotechnology for Biofuels, 2018Co-Authors: Xiao-man Sun, Lujing Ren, Quanyu Zhao, Ling Jiang, He HuangAbstract:Schizochytrium sp. is a marine microalga with great potential as a promising sustainable source of lipids rich in docosahexaenoic acid (DHA). This organism’s lipid accumulation machinery can be induced by various stress conditions, but this stress induction usually comes at the expense of lower biomass in industrial fermentations. Moreover, oxidative damage induced by various environmental stresses can result in the peroxidation of lipids, and especially polyunsaturated fatty acids, which causes unstable DHA production, but is often ignored in fermentation processes. Therefore, it is urgent to develop new production strains that not only have a high DHA production capacity, but also possess strong antioxidant defenses. Adaptive laboratory evolution (ALE) is an effective method for the development of beneficial phenotypes in industrial microorganisms. Here, a novel cooperative two-factor ALE strategy based on concomitant low temperature and high salinity was applied to improve the production capacity of Schizochytrium sp. Low-temperature conditions were used to improve the DHA content, and high salinity was applied to stimulate lipid accumulation and enhance the antioxidative defense systems of Schizochytrium sp. After 30 adaptation cycles, a maximal cell dry weight of 126.4 g/L and DHA yield of 38.12 g/L were obtained in the endpoint strain ALE-TF30, which was 27.42 and 57.52% higher than parental strain, respectively. Moreover, the fact that ALE-TF30 had the lowest concentrations of reactive oxygen species and malondialdehyde among all strains indicated that lipid peroxidation was greatly suppressed by the evolutionary process. Accordingly, the ALE-TF30 strain exhibited an overall increase of gene expression levels of antioxidant enzymes and polyketide synthases compared to the parental strain. This study provides important clues on how to overcome the negative effects of lipid peroxidation on DHA production in Schizochytrium sp. Taken together, the cooperative two-factor ALE process can not only increase the accumulation of lipids rich in DHA, but also prevent the loss of produced lipid caused by lipid peroxidation. The strategy proposed here may provide a new and alternative direction for the industrial cultivation of oil-producing microalgae.
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Transcriptome and gene expression analysis of docosahexaenoic acid producer Schizochytrium sp. under different oxygen supply conditions
BMC, 2018Co-Authors: Lujing Ren, Xiao-man Sun, Si-yu Zhu, He HuangAbstract:Abstract Background Schizochytrium 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. Results Two 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. Conclusions This 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
Lujing Ren - One of the best experts on this subject based on the ideXlab platform.
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Integration of lipidomic and transcriptomic profiles reveals novel genes and regulatory mechanisms of Schizochytrium sp. in response to salt stress.
Bioresource Technology, 2019Co-Authors: Jia-yi Jiang, He Huang, Xiao-man Sun, Si-yu Zhu, Yu-ting Zhang, Lujing RenAbstract:In this study, the effects of salt stress on the physiological, lipidomic and transcriptomic profiles of halophilic microalga Schizochytrium sp. were investigated. In general, Schizochytrium sp. could survive under high osmotic fermentation medium containing 30 g/L NaCl, and showed a significant increase in C14:0 percentage in total fatty acids. In lipidomic analysis, C14:0 was specifically enriched in phosphatidylcholine (PC), and membrane phospholipids participated in the salt stress response mostly. Specially, one novel signal lipid N-acylphosphatidylethanolamine (NAPE) (18:0/20:3/14:0) was upregulated significantly. Transcriptomic analysis revealed glycerol-3-phosphate acyltransferase (GPAT) and phospholipase ABHD3 (PLABDH3) were involved in C14:0 metabolism and NAPE biosynthesis. Signalling pathways they mediated were activated as evident by high expression level of Myristoyl-CoA: protein N-myristoyltransferase (NMT) and NAPE-hydrolyzing PLD (NAPE-PLD). This study gives us an insight in specific responses to salt stress in Schizochytrium sp. and provides a considerable proportion of novel genes that could commendably be used for engineering modification.
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Development of a strategy for the production of docosahexaenoic acid by Schizochytrium sp. from cane molasses and algae-residue.
Bioresource Technology, 2018Co-Authors: Feng-wei Yin, Lujing Ren, He Huang, Si-yu Zhu, Dong-sheng Guo, Zhen GaoAbstract:Abstract The aim of this work was to reduce the algae-residue emission and make use of cane molasses as fermentation materials for docosahexaenoic acid (DHA) fermentaion by Schizochytrium sp., which further could cut the cost of DHA production. Algae-residue and cane molasses were respectively used as nitrogen and carbon sources to replace yeast extract and glucose. A significant DHA yield of 18.58 g/L was obtained using algae-residue, while cane molasses could not be used well as sole carbon source due to the presence of undesirable substance. A two-stage culture strategy with glucose followed by pretreated cane molasses as carbon source was developed, resulting in a final DHA yield of 15.22 g/L. This study therefore offers an economical and green strategy for DHA production by Schizochytrium sp.
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Transcriptome and gene expression analysis of docosahexaenoic acid producer Schizochytrium sp. under different oxygen supply conditions.
Biotechnology for Biofuels, 2018Co-Authors: Lujing Ren, Xiao-man Sun, Si-yu Zhu, He HuangAbstract:Schizochytrium 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. Two 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. This 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.
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development of a cooperative two factor adaptive evolution method to enhance lipid production and prevent lipid peroxidation in Schizochytrium sp
Biotechnology for Biofuels, 2018Co-Authors: Xiao-man Sun, Lujing Ren, Quanyu Zhao, Ling Jiang, He HuangAbstract:Schizochytrium sp. is a marine microalga with great potential as a promising sustainable source of lipids rich in docosahexaenoic acid (DHA). This organism’s lipid accumulation machinery can be induced by various stress conditions, but this stress induction usually comes at the expense of lower biomass in industrial fermentations. Moreover, oxidative damage induced by various environmental stresses can result in the peroxidation of lipids, and especially polyunsaturated fatty acids, which causes unstable DHA production, but is often ignored in fermentation processes. Therefore, it is urgent to develop new production strains that not only have a high DHA production capacity, but also possess strong antioxidant defenses. Adaptive laboratory evolution (ALE) is an effective method for the development of beneficial phenotypes in industrial microorganisms. Here, a novel cooperative two-factor ALE strategy based on concomitant low temperature and high salinity was applied to improve the production capacity of Schizochytrium sp. Low-temperature conditions were used to improve the DHA content, and high salinity was applied to stimulate lipid accumulation and enhance the antioxidative defense systems of Schizochytrium sp. After 30 adaptation cycles, a maximal cell dry weight of 126.4 g/L and DHA yield of 38.12 g/L were obtained in the endpoint strain ALE-TF30, which was 27.42 and 57.52% higher than parental strain, respectively. Moreover, the fact that ALE-TF30 had the lowest concentrations of reactive oxygen species and malondialdehyde among all strains indicated that lipid peroxidation was greatly suppressed by the evolutionary process. Accordingly, the ALE-TF30 strain exhibited an overall increase of gene expression levels of antioxidant enzymes and polyketide synthases compared to the parental strain. This study provides important clues on how to overcome the negative effects of lipid peroxidation on DHA production in Schizochytrium sp. Taken together, the cooperative two-factor ALE process can not only increase the accumulation of lipids rich in DHA, but also prevent the loss of produced lipid caused by lipid peroxidation. The strategy proposed here may provide a new and alternative direction for the industrial cultivation of oil-producing microalgae.
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Transcriptome and gene expression analysis of docosahexaenoic acid producer Schizochytrium sp. under different oxygen supply conditions
BMC, 2018Co-Authors: Lujing Ren, Xiao-man Sun, Si-yu Zhu, He HuangAbstract:Abstract Background Schizochytrium 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. Results Two 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. Conclusions This 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
Peter D Nichols - One of the best experts on this subject based on the ideXlab platform.
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comparison of thraustochytrids aurantiochytrium sp Schizochytrium sp thraustochytrium sp and ulkenia sp for production of biodiesel long chain omega 3 oils and exopolysaccharide
Marine Biotechnology, 2014Co-Authors: Kim Jye Lee Chang, Carol Mancuso Nichols, Susan I Blackburn, Graeme A Dunstan, Anthony Koutoulis, Peter D NicholsAbstract:Heterotrophic growth of thraustochytrids has potential in coproducing biodiesel for transportation, as well as producing a feedstock for omega-3 long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA), especially docosahexaenoic acid (DHA) for use in nutraceuticals. In this study, we compared eight new endemic Australian thraustochytrid strains from the genera Aurantiochytrium, Schizochytrium, Thraustochytrium, and Ulkenia for the synthesis of exopolysaccharide (EPS), in addition to biodiesel and LC-PUFA. Aurantiochytrium sp. strains readily utilized glucose for biomass production, and increasing glucose from 2 to 4 % w/v of the culture medium resulted in increased biomass yield by an average factor of 1.7. Ulkenia sp. strain TC 010 and Thraustochytrium sp. strain TC 033 did not utilize glucose, while Schizochytrium sp. strain TC 002 utilized less than half the glucose available by day 14, and Thraustochytrium sp. strain TC 004 utilized glucose at 4 % w/v but not 2 % w/v of the culture suggesting a threshold requirement between these values. Across all strains, increasing glucose from 2 to 4 % w/v of the culture medium resulted in increased total fatty acid methyl ester content by an average factor of 1.9. Despite an increasing literature demonstrating the capacity of thraustochytrids for DHA synthesis, the production of EPS from these organisms is not well documented. A broad range of EPS yields was observed. The maximum yield of EPS was observed for Schizochytrium sp. strain TC 002 (299 mg/L). High biomass-producing strains that also have high lipid and high EPS yield may be better candidates for commercial production of biofuels and other coproducts.
Zhaokai Wang - One of the best experts on this subject based on the ideXlab platform.
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Low-temperature effects on docosahexaenoic acid biosynthesis in Schizochytrium sp. TIO01 and its proposed underlying mechanism.
Biotechnology for biofuels, 2020Co-Authors: April L. Clevenger, Peng Zheng, Qiongye Huang, Zhaokai WangAbstract:Schizochytrium species are known for their abundant production of docosahexaenoic acid (DHA). Low temperatures can promote the biosynthesis of polyunsaturated fatty acids (PUFAs) in many species. This study investigates low-temperature effects on DHA biosynthesis in Schizochytrium sp. TIO01 and its underlying mechanism. The Schizochytrium fatty acid biosynthesis pathway was evaluated based on de novo genome assembly (contig N50 = 2.86 Mb) and iTRAQ-based protein identification. Our findings revealed that desaturases, involved in DHA synthesis via the fatty acid synthase (FAS) pathway, were completely absent. The polyketide synthase (PKS) pathway and the FAS pathway are, respectively, responsible for DHA and saturated fatty acid synthesis in Schizochytrium. Analysis of fatty acid composition profiles indicates that low temperature has a significant impact on the production of DHA in Schizochytrium, increasing the DHA content from 43 to 65% of total fatty acids. However, the expression levels of PKS pathway genes were not significantly regulated as the DHA content increased. Further, gene expression analysis showed that pathways related to the production of substrates (acetyl-CoA and NADPH) for fatty acid synthesis (the branched-chain amino acid degradation pathway and the pentose phosphate pathway) and genes related to saturated fatty acid biosynthesis (the FAS pathway genes and malic enzyme) were, respectively, upregulated and downregulated. These results indicate that low temperatures increase the DHA content by likely promoting the entry of relatively large amounts of substrates into the PKS pathway. In this study, we provide genomic, proteomic, and transcriptomic evidence for the fatty acid synthesis pathway in Schizochytrium and propose a mechanism by which low temperatures promote the accumulation of DHA in Schizochytrium. The high-quality and nearly complete genome sequence of Schizochytrium provides a valuable reference for investigating the regulation of polyunsaturated fatty acid biosynthesis and the evolutionary characteristics of Thraustochytriidae species. © The Author(s) 2020.
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The effects of low temperature on docosahexaenoic acid biosynthesis in Schizochytrium sp TIO01 and the underlying mechanism
2020Co-Authors: April L. Clevenger, Peng Zheng, Qiongye Huang, Zhaokai WangAbstract:Abstract Background Schizochytrium are known for their abundant production of docosahexaenoic acid (DHA). Low temperatures can promote the biosynthesis of polyunsaturated fatty acids in many species. In this study, the effects of low temperature on the biosynthesis of DHA in Schizochytrium sp TIO01 and the underlying mechanism was investigated. Results Based on the de novo genome assembly (contig N50=2.86 Mb) and iTRAQ-based protein identification, we first reconstructed the detailed Schizochytrium fatty acid biosynthesis pathway. Our findings revealed that desaturases, involved in DHA synthesis via the fatty acid synthase (FAS) pathway, were completely absent. The polyketide synthase (PKS) pathway and the FAS pathway are separately responsible for DHA and saturated fatty acid synthesis in Schizochytrium . Analysis of fatty acid composition profiles indicates that low temperature has a significant impact on the production of DHA in Schizochytrium, increasing the DHA content and overall total fatty acids from 43% to 65%. The increased DHA content, however, was not a result of the expression of the PKS pathway genes. Further gene expression analysis indicated that low temperatures may promote DHA accumulation by the up-regulation of both the pentose phosphate pathway and the branched-chain amino acid degradation pathway (increasing the production of the substrates for polyunsaturated fatty acid synthesis: acetyl-CoA and NADPH). In addition, low temerpatures result in a down-regulation of the FAS pathway (reducing the consumption of the substrates for saturated fatty acid synthesis) and malic enzyme, leading to a decreased saturated fatty acid content. Conclusions These findings elucidate the detailed fatty acid synthesis pathway of Schizochytrium, revealing an underlying mechanism by which low temperatures promote the accumulation of DHA in Schizochytrium. The high-quality and nearly complete genome sequence of Schizochytrium provides a valuable reference for further investigation of the regulation of polyunsaturated fatty acids biosynthesisand the evolutionary characteristics in Thraustochytriidae species.
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Complete mitochondrial genome of a DHA-rich protist Schizochytrium sp. TIO1101
Mitochondrial DNA Part B, 2016Co-Authors: Zhaokai Wang, Sulin Lou, Hu Fan, Wu Peng, Longhe Yang, Xiangzhi LinAbstract:AbstractSchizochytrium sp. TIO1101 is a crucial commercial alga used to produce docosahexaenoic acid (DHA), a long-chain polyunsaturated fatty acid that is beneficial for human health. In this study, we sequenced the mitochondrial genome (mitogenome) of Schizochytrium sp. TIO1101 for the first time using an Illumina HiSeq 2500 system (Illumina Inc., San Deigo, CA). The assembled mitogenome was 31 494 bp long with 33.92% GC content. The mitogenome contains 56 genes, including 33 protein-coding genes, 21 transfer RNA genes and two ribosomal RNA genes. Maximum-likelihood phylogenetic analysis of Schizochytrium sp. TIO1101 showed that it was most closely related to Thraustochytrium aureum among the examined species.
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Agrobacterium tumefaciens mediated transformation of marine microalgae Schizochytrium.
Microbiological Research, 2012Co-Authors: Ru-bin Cheng, Zhaokai Wang, Ma Ruijuan, Rong Hui, Xiangzhi Lin, Yang Shanjun, Ma YongAbstract:Schizochytrium was a known docosahexaenoic acid producing marine microalgae. In this study, we have developed a novel transformation approach of Schizochytrium using the Agrobacterium tumefaciens (A. tumefaciens) binary vector system. After co-cultivation of Schizochytrium protoplasts with A. tumefaciens harboring pCAMBIA2301 containing the neomycin phosphotransferase II (NPT II) gene as the selectable marker which confers resistance to G418, the Schizochytrium transformants were successfully obtained on the G418-containing plates. The integration and expression of the transgenes were confirmed by PCR analysis and GUS activity assay. To further validate the transformation system, pCAMBIA2301-EGFP containing the egfp gene was introduced into Schizochytrium. The following results demonstrated that the exogenous egfp gene has been successfully incorporated into the genome of Schizochytrium. In addition, the introduced egfp gene expressed efficiently according to the Western blot and fluorescence assay results. More importantly, the majority of the transformants displayed similar biomass and fatty acid production comparing with the wild type strain. Our results demonstrated that exogenous genes could be expressed efficiently in transgenic Schizochytrium, suggesting that genetically engineered Schizochytrium could be explored by this system.
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Establishment of a transgene expression system for the marine microalga Schizochytrium by 18S rDNA-targeted homologous recombination
World Journal of Microbiology & Biotechnology, 2010Co-Authors: Ru-bin Cheng, Shanjun Yang, Zhaokai Wang, Hui Rong, Yong MaAbstract:Schizochytrium is an established candidate for commercial production of long chain polyunsaturated fatty acids (PUFAs) that are important in human health and aquaculture. Genetic engineering technology has been applied successfully to increase the metabolites in many organisms. In order to use genetic engineering technology to enhance lipid accumulation in Schizochytrium for economically feasible PUFAs production, the transgene expression system should be established first. In the present study, we investigated a novel transgene expression system in Schizochytrium by 18S rDNA-targeted homologous recombination. The targeting vector pBS-18S-ZeoR contains a portion of 18S rDNA from Schizochytrium and the Zeocin resistance gene (Streptoalloteichus hindustanus bleomycin gene, Sh ble gene) expression cassette. This targeting vector was transformed into Schizochytrium by electroporation and the transformants were then selected on Zeocin-containing plates. The exogenous Sh ble gene has been incorporated into the genome of Schizochytrium according to PCR amplification. More importantly, the majority of the transformants showed similar biomass and total lipid to the wild type strain. Our results suggest that the 18S rDNA is a suitable recombination site and this system could be used to introduce new functional genes into Schizochytrium.
Kim Jye Lee Chang - One of the best experts on this subject based on the ideXlab platform.
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comparison of thraustochytrids aurantiochytrium sp Schizochytrium sp thraustochytrium sp and ulkenia sp for production of biodiesel long chain omega 3 oils and exopolysaccharide
Marine Biotechnology, 2014Co-Authors: Kim Jye Lee Chang, Carol Mancuso Nichols, Susan I Blackburn, Graeme A Dunstan, Anthony Koutoulis, Peter D NicholsAbstract:Heterotrophic growth of thraustochytrids has potential in coproducing biodiesel for transportation, as well as producing a feedstock for omega-3 long-chain (≥C20) polyunsaturated fatty acids (LC-PUFA), especially docosahexaenoic acid (DHA) for use in nutraceuticals. In this study, we compared eight new endemic Australian thraustochytrid strains from the genera Aurantiochytrium, Schizochytrium, Thraustochytrium, and Ulkenia for the synthesis of exopolysaccharide (EPS), in addition to biodiesel and LC-PUFA. Aurantiochytrium sp. strains readily utilized glucose for biomass production, and increasing glucose from 2 to 4 % w/v of the culture medium resulted in increased biomass yield by an average factor of 1.7. Ulkenia sp. strain TC 010 and Thraustochytrium sp. strain TC 033 did not utilize glucose, while Schizochytrium sp. strain TC 002 utilized less than half the glucose available by day 14, and Thraustochytrium sp. strain TC 004 utilized glucose at 4 % w/v but not 2 % w/v of the culture suggesting a threshold requirement between these values. Across all strains, increasing glucose from 2 to 4 % w/v of the culture medium resulted in increased total fatty acid methyl ester content by an average factor of 1.9. Despite an increasing literature demonstrating the capacity of thraustochytrids for DHA synthesis, the production of EPS from these organisms is not well documented. A broad range of EPS yields was observed. The maximum yield of EPS was observed for Schizochytrium sp. strain TC 002 (299 mg/L). High biomass-producing strains that also have high lipid and high EPS yield may be better candidates for commercial production of biofuels and other coproducts.
