The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Owen P. Ward - One of the best experts on this subject based on the ideXlab platform.
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Docosahexaenoic acid (DHA) production by Thraustochytrium sp. ATCC 20892.
World journal of microbiology & biotechnology, 1996Co-Authors: Ajay Singh, S. Wilson, Owen P. WardAbstract:Thraustochytrium sp. ATCC 20892 produced high yields of docosahexaenoic acid (DHA), more than four other strains of Thraustochytrium and Schizochytrium tested, but insignificant amounts of other polyunsaturated fatty acids. Glucose and sodium glutamate were the preferred carbon and nitrogen sources, respectively, and the optimum conditions for growth and DHA production were pH 7.0 at 25°C with 40 g glucose 1-1 for 4 days. Temperature profiling under these optimum conditions further enhanced the yield and volumetric productivity of DHA.
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Production of docosahexaenoic acid by Thraustochytrium roseum.
Journal of industrial microbiology, 1994Co-Authors: Owen P. WardAbstract:When three Thraustochytrium stains were cultivated in liquid media containing 2.5% starch and 0.2% yeast extract, initial pH 6.0, with shaking under fluorescent light for five days at 25 degrees C, similar biomass yields were observed (9.7-10.3 g L-1). Contents of docosahexaenoic acid (DHA) in biomass varied: 0.15, 3.55 and 6.40% w/w for T. striatum ATCC 24473. T. aureum ATCC 34304 and T. roseum ATCC 28210, respectively. In further studies, T. roseum produced a maximum titer of 0.85 g of DHA per liter of culture broth. The DHA content of total lipids ranged from 46-49% w/w.
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Production of docosahexaenoic acid by Thraustochytrium aureum
Applied Microbiology and Biotechnology, 1991Co-Authors: Pratima Bajpai, Pramod K. Bajpai, Owen P. WardAbstract:Thraustochytrium aureum ATCC 34 304 contained approximately 50% of total fatty acids as docosahexaenoic acid (DHA). Lipid content of the biomass was dramatically influenced by medium composition and ranged from 0.3 to 16% of the biomass weight. Increasing the culture medium glucose concentration from 5 to 20 g/l caused the lipid content of the biomass to increase from 2.7 to 16.5% and the DHA yield to increase from 26 to 270 mg/l of whole culture broth. The proportion of DHA in lipids was independent of glucose concentration. The fatty acid profile observed in the high-yielding DHA culture was: 16:0, 19.2%; 18:1, 9.8%; 18:2, 2.4%; 20:4, 4.9%; 20:5, 3.6%; 22:6, 48.5% and others, 7.1%. For DHA production, fungal cultures were incubated on an orbital shaker under light at 25° C for 6 days.
Colin J Barrow - One of the best experts on this subject based on the ideXlab platform.
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comparison of cell disruption methods for improving lipid extraction from thraustochytrid strains
Marine Drugs, 2015Co-Authors: Avinesh R Byreddy, Adarsha Gupta, Colin J Barrow, Munish PuriAbstract:Lipid extraction is an integral part of biodiesel production, as it facilitates the release of fatty acids from algal cells. To utilise thraustochytrids as a potential source for lipid production. We evaluated the extraction efficiency of various solvents and solvent combinations for lipid extraction from Schizochytrium sp. S31 and Thraustochytrium sp. AMCQS5-5. The maximum lipid extraction yield was 22% using a chloroform:methanol ratio of 2:1. We compared various cell disruption methods to improve lipid extraction yields, including grinding with liquid nitrogen, bead vortexing, osmotic shock, water bath, sonication and shake mill. The highest lipid extraction yields were obtained using osmotic shock and 48.7% from Schizochytrium sp. S31 and 29.1% from Thraustochytrium sp. AMCQS5-5. Saturated and monounsaturated fatty acid contents were more than 60% in Schizochytrium sp. S31 which suggests their suitability for biodiesel production.
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Evaluation of bread crumbs as a potential carbon source for the growth of thraustochytrid species for oil and omega-3 production.
Nutrients, 2014Co-Authors: Tamilselvi Thyagarajan, Munish Puri, Jitraporn Vongsvivut, Colin J BarrowAbstract:The utilization of food waste by microorganisms to produce omega-3 fatty acids or biofuel is a potentially low cost method with positive environmental benefits. In the present study, the marine microorganisms Thraustochytrium sp. AH-2 and Schizochytrium sp. SR21 were used to evaluate the potential of breadcrumbs as an alternate carbon source for the production of lipids under static fermentation conditions. For the Thraustochytrium sp. AH-2, submerged liquid fermentation with 3% glucose produced 4.3 g/L of biomass and 44.16 mg/g of saturated fatty acids after seven days. Static fermentation with 0.5% and 1% breadcrumbs resulted in 2.5 and 4.7 g/L of biomass, and 42.4 and 33.6 mg/g of saturated fatty acids, respectively. Scanning electron microscopic (SEM) studies confirmed the growth of both strains on breadcrumbs. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy for both strains were consistent with the utilization of breadcrumbs for the production of unsaturated lipids, albeit at relatively low levels. The total lipid yield for static fermentation with bread crumbs was marginally lower than that of fermentation with glucose media, while the yield of unsaturated fatty acids was considerably lower, indicating that static fermentation may be more appropriate for the production of biodiesel than for the production of omega-3 rich oils in these strains.
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Evaluation of fatty acid extraction methods for Thraustochytrium sp. ONC-T18.
Journal of agricultural and food chemistry, 2007Co-Authors: Adam M. Burja, Roberto Armenta, Helia Radianingtyas, Colin J BarrowAbstract:Various extraction methods were assessed in their capacity to extract fatty acids from a dried biomass of Thraustochytrium sp. ONC-T18. Direct saponification using KOH in ethanol or in hexane:ethanol was one of the most efficient techniques to extract lipids (697 mg g(-1)). The highest amount of fatty acids (714 mg g(-1)) was extracted using a miniaturized Bligh and Dyer extraction technique. The use of ultrasonics to break down cell walls while extracting with solvents (methanol:chloroform) also offered high extraction yields of fatty acids (609 mg g(-1)). Moreover, when the transesterification mixture used for a direct transesterification method was doubled, the extraction of fatty acids increased approximately 77% (from 392 to 696 mg g(-1)). This work showed that Thraustochytrium sp. ONC-T18 has the ability to produce over 700 mg g(-1) of lipids, including more than 165 mg g(-1) of docosahexaenoic acid, which makes this microorganism a potential candidate for the commercial production of polyunsaturated fatty acids. Finally, other lipids, such as myristic, palmitic, palmitoleic, and oleic acids, were also produced and recovered in significant amounts (54, 196, 123, and 81 mg g(-1)), respectively.
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Isolation and characterization of polyunsaturated fatty acid producing Thraustochytrium species: screening of strains and optimization of omega-3 production
Applied Microbiology and Biotechnology, 2006Co-Authors: Adam M. Burja, Helia Radianingtyas, Anthony Windust, Colin J BarrowAbstract:An isolation program targeting Thraustochytrids (marine fungoid protists) from 19 different Atlantic Canadian locations was performed. Sixty-eight isolates were screened for biomass, total fatty acid (TFA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) content. Analysis of fatty acid methyl ester results discerned four distinctive clusters based on fatty acid profiles, with biomass ranging from 0.1 to 2.3 g L^−1, and lipid, EPA, and DHA contents ranging from 27.1 to 321.14, 2.97 to 21.25, and 5.18 to 83.63 mg g^−1 biomass, respectively. ONC-T18, was subsequently chosen for further manipulations. Identified using 18S rRNA gene sequencing techniques as a Thraustochytrium sp., most closely related to Thraustochytrium striatum T91-6, ONC-T18 produced up to 28.0 g L^−1 biomass, 81.7% TFA, 31.4% (w/w biomass) DHA, and 4.6 g L^−1 DHA under optimal fermentation conditions. Furthermore, this strain was found to produce the carotenoids and xanthophylls astaxanthin, zeaxanthin, canthaxanthin, echinenone, and β-carotene. Given this strain’s impressive productivity when compared to commercial strains, such as Schizochytrium sp. SR21 (which has only 50% TFA), coupled with its ability to grow at economical nitrogen and very low salt concentrations (2 g L^−1), ONC-T18 is seen as an ideal candidate for both scale-up and commercialization.
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isolation and characterization of polyunsaturated fatty acid producing Thraustochytrium species screening of strains and optimization of omega 3 production
Applied Microbiology and Biotechnology, 2006Co-Authors: Adam M. Burja, Helia Radianingtyas, Anthony Windust, Colin J BarrowAbstract:An isolation program targeting Thraustochytrids (marine fungoid protists) from 19 different Atlantic Canadian locations was performed. Sixty-eight isolates were screened for biomass, total fatty acid (TFA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) content. Analysis of fatty acid methyl ester results discerned four distinctive clusters based on fatty acid profiles, with biomass ranging from 0.1 to 2.3 g L(-1), and lipid, EPA, and DHA contents ranging from 27.1 to 321.14, 2.97 to 21.25, and 5.18 to 83.63 mg g(-1) biomass, respectively. ONC-T18, was subsequently chosen for further manipulations. Identified using 18S rRNA gene sequencing techniques as a Thraustochytrium sp., most closely related to Thraustochytrium striatum T91-6, ONC-T18 produced up to 28.0 g L(-1) biomass, 81.7% TFA, 31.4% (w/w biomass) DHA, and 4.6 g L(-1) DHA under optimal fermentation conditions. Furthermore, this strain was found to produce the carotenoids and xanthophylls astaxanthin, zeaxanthin, canthaxanthin, echinenone, and beta-carotene. Given this strain's impressive productivity when compared to commercial strains, such as Schizochytrium sp. SR21 (which has only 50% TFA), coupled with its ability to grow at economical nitrogen and very low salt concentrations (2 g L(-1)), ONC-T18 is seen as an ideal candidate for both scale-up and commercialization.
Jo Shu Chang - One of the best experts on this subject based on the ideXlab platform.
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Biodiesel production from heterotrophic oleaginous microalga Thraustochytrium sp. BM2 with enhanced lipid accumulation using crude glycerol as alternative carbon source.
Bioresource technology, 2020Co-Authors: Chun Yen Chen, Meng Hsiu Lee, Yoong Kit Leong, Jo Shu Chang, Duu-jong LeeAbstract:Abstract Aiming to improve the economy and sustainability of biodiesel production, the scale-up of lipid production by heterotrophic Thraustochytrium sp. BM2 utilizing crude glycerol as a low cost carbon source was optimized in stirred tank fermenter. The issues of impurities such as excess ions, methanol, soap and other organic impurities as well as different pretreatment techniques were explored and tackled for industrial application of crude glycerol as carbon source. For process engineering strategies to enhance lipid production, semi-batch operation outperformed fed-batch cultivation and achieved higher lipid yield and overall lipid productivity primarily due to shorter fermentation time. The two-step esterification/transesterification method achieved high fatty acid methyl ester (FAME) conversion rate up to 91.8%, which was two to three folds higher compared with the one-step process.
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Enhanced production of microalgal lipids using a heterotrophic marine microalga Thraustochytrium sp. BM2
Biochemical Engineering Journal, 2020Co-Authors: Chun Yen Chen, Meng Hsiu Lee, Yoong Kit Leong, Cheng-di Dong, Jo Shu ChangAbstract:Abstract In this study, the potential of Thraustochytrium sp. BM2 for cost-effective lipid production was investigated. Lipid content and productivity of BM2 reached 76% and 37 mg/L/h when corn steep liquor (12.5 g/L) and glycerol (10 g/L) was used as nitrogen and carbon source respectively. Supplementing an optimal amount of sea salt (2% w/v) further enhanced the lipid content to 79%. The inoculum size and age were also evaluated for their effect on lipid accumulation. A 48-h pre-culture at 0.15 g/L loading further improved the lipid productivity to 43.86 mg/L/h (or 1.052 g/L/d), which is a 340% increase when compared with the control test. Thus, Thraustochytrium sp. BM2 strain could serve as a low-cost and high-lipid-yield heterotrophic lipid producer using glycerol (a by-product of biodiesel manufacturing process) as carbon source and an inexpensive nitrogen source (i.e., corn steep liquor).
Baoyu Tian - One of the best experts on this subject based on the ideXlab platform.
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cloning and functional identification of delta5 fatty acid desaturase gene and its 5 upstream region from marine fungus Thraustochytrium sp fjn 10
Marine Biotechnology, 2011Co-Authors: Jianzhong Huang, Xianzhang Jiang, Xiaofeng Xia, Ruoyu Mao, Xiaofeng Chen, Baoyu TianAbstract:A gene encoding delta5 fatty acid desaturase (fad5) was cloned from marine fungus Thraustochytrium sp. FJN-10, a species capable of producing docosahexaenoic acid. The open reading frame of fad5 was 1,320 bp and encoded a protein comprising 439 amino acids. Expression of the fad5 in Saccharomyces cerevisiae INVSC1 revealed that FAD5 is able to introduce a double bond at position 5 of the dihomo-γ-linolenic acid (20:3 Δ8,11,14), resulting in arachidonic acid (20:4 Δ5,8,11,14) with a conversion rate of 56.40% which is the highest among engineering yeasts reported so far. The 5′-upstream region of fad5 was cloned by LA-PCR and analyzed. Phylogenetic analysis of this sequence with the 5′-upstream region of other delta5 desaturases showed that the 5′-upstream region of fad5 from Thraustochytrium share the smallest evolution distance with human and rhesus. Computational analysis of the nucleotide sequence of the 5′-upstream region of fad5 has revealed several basic transcriptional elements including five TATA boxes, three CCAAT boxes, 12 GC boxes, and several putative target-binding sites for transcription factors such as HSF, CAP, and ADR1. Preliminary functional analysis of this promoter in S. cerevisiae shows that the 5′-upstream region of fad5 could drive the expression of green fluorescent protein.
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Cloning and Functional Identification of Delta5 Fatty Acid Desaturase Gene and Its 5′-Upstream Region from Marine Fungus Thraustochytrium sp. FJN-10
Marine biotechnology (New York N.Y.), 2010Co-Authors: Jianzhong Huang, Xianzhang Jiang, Xiaofeng Xia, Ruoyu Mao, Xiaofeng Chen, Baoyu TianAbstract:A gene encoding delta5 fatty acid desaturase (fad5) was cloned from marine fungus Thraustochytrium sp. FJN-10, a species capable of producing docosahexaenoic acid. The open reading frame of fad5 was 1,320 bp and encoded a protein comprising 439 amino acids. Expression of the fad5 in Saccharomyces cerevisiae INVSC1 revealed that FAD5 is able to introduce a double bond at position 5 of the dihomo-γ-linolenic acid (20:3 Δ8,11,14), resulting in arachidonic acid (20:4 Δ5,8,11,14) with a conversion rate of 56.40% which is the highest among engineering yeasts reported so far. The 5′-upstream region of fad5 was cloned by LA-PCR and analyzed. Phylogenetic analysis of this sequence with the 5′-upstream region of other delta5 desaturases showed that the 5′-upstream region of fad5 from Thraustochytrium share the smallest evolution distance with human and rhesus. Computational analysis of the nucleotide sequence of the 5′-upstream region of fad5 has revealed several basic transcriptional elements including five TATA boxes, three CCAAT boxes, 12 GC boxes, and several putative target-binding sites for transcription factors such as HSF, CAP, and ADR1. Preliminary functional analysis of this promoter in S. cerevisiae shows that the 5′-upstream region of fad5 could drive the expression of green fluorescent protein.
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Cloning and expression of two elongase genes involved in the biosynthesis of docosahexaenoic acid in Thraustochytrium sp. FJN-10
Wei sheng wu xue bao = Acta microbiologica Sinica, 2008Co-Authors: Xianzhang Jiang, Lina Qin, Baoyu Tian, Zhengyu Shu, Jianzhong HuangAbstract:Docosahexaenoic acid (DHA C22:6n-3), a typical long chain polyunsaturated fatty acids (PUFAs) has many positive effects on diseases such as artherosclerosis, hypertriglyceridemia, hypertension and cancers. Marine fungi, especially Thraustochytrium spp. producing much DHA can serve as model organisms for explaining the mechanism on the biosynthesis of PUFA. We described two elongase genes (TFD6 and TFD5) involved in the biosynthesis of DHA in Thraustochytrium sp. FJN-10 was cloned by using reverse transcription PCR and rapid amplification of cDNA ends. TFD6 cDNA was 816 bp in length and encoded a protein of 271 amino acids. TFD5 cDNA was 831 bp in length and encoded a protein of 276 amino acids. Transmembrane analysis revealed that TFD6 contained five transmembrane domains while TFD5 contained seven. Tertiary structures of TFD6, TFD5 elongases were predicted by HHMMSTR (Hidden markov model for local sequence-structure) model and Rosetta program. Alignment of TFD6, TFD5 with other elongases showed that both of them shared an HXXHH conserved histidine-rich motif. Phylogenetic analysis showed that TFD6 was the closest to Thraustochytrium 66 elongase, while TFD5 was the closest to Thraustochytrium sp. delta5 elongase. TFD6 and TFD5 were subcloned into the Hind III/Xba I restriction site of pYES2 vector respectively. Recombined plasmids were transformed into Saccharomyces cerevisiae using lithium acetate method. Gas chromatography analysis showed that TFD6 could elongate C18:3n-3 to C20:3n-3 while TFD5 could elongate C20:5n-3 to C22:5n-3.
Xiao Qiu - One of the best experts on this subject based on the ideXlab platform.
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Functional Analysis of an Acyltransferase-Like Domain from Polyunsaturated Fatty Acid Synthase in Thraustochytrium
Microorganisms, 2021Co-Authors: Carla Almendáriz-palacios, Dauenpen Meesapyodsuk, Xiao QiuAbstract:Biosynthesis of very long chain polyunsaturated fatty acids (VLCPUFA) such as docosahexaenoic acid (DHA, 22:6-4,7,10,13,16,19) and docosapentaenoic acid (DPA, 22:5-4,7,10,13,16) in protist Thraustochytrium is catalyzed by a polyunsaturated fatty acids (PUFA) synthase comprising three large subunits, each with multiple catalytic domains. This study used complementation test, in vitro assays, and functional expression to characterize an acyltransferase (AT)-like domain in Subunit-B of a PUFA synthase from Thraustochytrium. Complementation test in Escherichia coli showed that the AT-like domain could not restore the growth phenotype of a temperature-sensitive mutant (∆fabDts) defective in malonyl-CoA:ACP transacylase activity. In vitro assays showed that the AT-like domain possessed thioesterase activity towards a few acyl-CoAs tested where docosahexaenoyl-CoA (DHA-CoA) was the preferred substrate. Expression of this domain in an E. coli mutant (∆fadD) defective in acyl-CoA synthetase activity resulted in the increased accumulation of free fatty acids. Site-directed mutagenesis showed that the substitution of two putative active site residues, serine at 96 (S96) and histidine at 220 (H220), in the AT-like domain significantly reduced its activity towards DHA-CoA and accumulation of free fatty acids in the ∆fadD mutant. These results indicate that the AT-like domain of the PUFA synthase does not function as a malonyl-CoA:ACP transacylase, rather it functions as a thioesterase. It might catalyze the last step of the VLCPUFA biosynthesis by releasing freshly synthesized VLCPUFAs attached to ACP domains of the PUFA synthase in Thraustochytrium.
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Very Long Chain Polyunsaturated Fatty Acids Accumulated in Triacylglycerol Are Channeled From Phosphatidylcholine in Thraustochytrium
Frontiers in microbiology, 2019Co-Authors: Xianming Zhao, Xiao QiuAbstract:Thraustochytrium is a marine protist that can accumulate a large amount of very long chain polyunsaturated fatty acids (VLCPUFA) in triacylglycerols (TAG). How these freshly synthesized VLCPUFAs are channeled into TAG remains unknown. In this study, the glycerolipid profile of Thraustochytrium at log and stationary growth stages was first analyzed by lipidomic tools, and then 14C-acetate and 14C-glycerol were used to trace the flux of fatty acids and backbone in glycerolipids. Lipidomic analysis showed that VLCPUFAs were mostly allocated to phosphatidylcholine (PC) and TAG. PC possessed a relatively stable profile of VLCPUFAs, whereas TAG carrying VLCPUFAs were significantly increased at the stationary phase. 14C-acetate labeled VLCPUFAs were predominately incorporated into PC initially but were mostly found in TAG at later time of labeling. Positional analysis showed that PC had either one VLCPUFA at its sn-2 position (PC1) or two VLCPUFAs (PC2), while TAG incorporated VLCPUFAs almost exclusively at the sn-2 position. Similarly, 14C-glycerol was more efficiently incorporated into PC1 than TAG initially but was mostly found in TAG at later time of labeling, and diacylglycerol and PC1 shared a similar incorporation pattern. These results indicate that VLCPUFAs in TAG are mainly channeled from PC likely through diacylglycerol as the intermediate.
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Functional analysis of the dehydratase domains of a PUFA synthase from Thraustochytrium in Escherichia coli.
Applied microbiology and biotechnology, 2017Co-Authors: Xi Xie, Dauenpen Meesapyodsuk, Xiao QiuAbstract:Thraustochytrium sp. 26185, a unicellular marine protist, synthesizes docosahexaenoic acid, an omega-3 very long chain polyunsaturated fatty acid (VLC-PUFAs), by a polyunsaturated fatty acid (PUFA) synthase comprising three large subunits with multiple catalytic dehydratase (DH) domains critical for introducing double bonds at the specific position of fatty acids. To investigate functions of these DH domains, one DH domain from subunit-A and two DH domains from subunit-C of the PUFA synthase were dissected and expressed as stand-alone enzymes in Escherichia coli. The results showed that all these DH domains could complement the defective phenotype of a E. coli FabA temperature sensitive mutant, despite they have only modest sequence similarity with FabA, indicating they can function as 3-hydroxyacyl-ACP dehydratase for the biosynthesis of unsaturated fatty acids in E. coli. Site-directed mutagenesis analysis confirmed the authenticity of active site residues in these domains. In addition, overexpression of the three domains in a wild type E. coli strain resulted in the substantial alteration of fatty acid profiles including productions and ratio of unsaturated to saturated fatty acids. A combination of evidences from sequence comparison, functional expression, and mutagenesis analysis suggest that the DH domain from subunit-A is similar to DH domains from polyketide synthases, while the DH domains from subunit-C are more comparable to E. coli FabA in catalytic functions. Successful complementation and functional expression of the embedded DH domains from the PUFA synthase in E. coli is an important step towards for elucidating the molecular mechanism in the biosynthesis of VLC-PUFAs in Thraustochytrium.
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Analysis of the biosynthetic process of fatty acids in Thraustochytrium.
Biochimie, 2017Co-Authors: Xianming Zhao, Xiao QiuAbstract:Abstract Thraustochytrium is a marine protist producing a specific profile of nutritionally important fatty acids, including very long chain polyunsaturated fatty acids (VLCPUFAs) docosahexaenoic acid (DHA, 22:6n-3), even chain saturated fatty acids (SFAs) palmitic acid (16:0), and odd chain SFAs pentadecanoic acid (15:0). To study how these fatty acids are synthesized, a series of radiolabeled precursors were used to trace the biosynthetic process in vivo and in vitro. When Thraustochytrium was fed with long chain fatty acid intermediates such as [1–14C]-oleic acid, [1–14C]-linoleic acid and [1–14C]-α-linolenic acid, no VLCPUFAs were produced, indicating that the aerobic pathway for the biosynthesis of VLCPUFAs was not functional in Thraustochytrium. When fed with [1–14C]-acetic acid, both SFAs and VLCPUFAs were labeled, and when fed with [1–14C]-propionic acid, mainly SFAs were labeled. However, when fed with [1–14C]-acetic acid in the presence of cerulenin, a type I FAS inhibitor, only VLCPUFAs were labeled, and when fed with [1–14C]-propionic acid in the presence of cerulenin, neither SFAs nor VLCPUFAs were labeled. This result clearly indicates that the type I fatty acid synthase (FAS) in Thraustochytrium could use acetic acid and propionic acid as the primers to synthesize even chain and odd chain SFAs, respectively, and VLCPUFAs were synthesized by the PUFA synthase using acetic acid as the primer. In addition, radioactive acetic acid could label both phospholipids (PL) and triacylglycerols (TAG), and VLCPUFAs appeared first and were largely accumulated in PL, whereas TAG accumulated much more SFAs than VLCPUFAs. The in vitro assay with [1–14C]-malonyl-CoA in presence of cerulenin showed that the crude protein of Thraustochytrium produced only VLCPUFAs, not SFAs, further confirming the role of the PUFA synthase in the biosynthesis of VLCPUFAs. Collectively, these results have elucidated the biochemical mechanisms for the biosynthesis of all fatty acids in Thraustochytrium.
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Biosynthetic mechanism of very long chain polyunsaturated fatty acids in Thraustochytrium sp. 26185
Journal of lipid research, 2016Co-Authors: Dauenpen Meesapyodsuk, Xiao QiuAbstract:Thraustochytrium, a unicellular marine protist, has been used as a commercial source of very long chain PUFAs (VLCPUFAs) such as DHA (22:6n-3). Our recent work indicates coexistence of a Δ4-desaturation-dependent pathway (aerobic) and a polyketide synthase-like PUFA synthase pathway (anaerobic) to synthesize the fatty acids in Thraustochytrium sp. 26185. Heterologous expression of the Thraustochytrium PUFA synthase along with a phosphopantetheinyl transferase in Escherichia coli showed the anaerobic pathway was highly active in the biosynthesis of VLCPUFAs. The amount of Δ4 desaturated VLCPUFAs produced reached about 18% of the total fatty acids in the transformant cells at day 6 in a time course of the induced expression. In Thraustochytrium, the expression level of the PUFA synthase gene was much higher than that of the Δ4 desaturase gene, and also highly correlated with the production of VLCPUFAs. On the other hand, Δ9 and Δ12 desaturations in the aerobic pathway were either ineffective or absent in the species, as evidenced by the genomic survey, heterologous expression of candidate genes, and in vivo feeding experiments. These results indicate that the anaerobic pathway is solely responsible for the biosynthesis for VLCPUFAs in Thraustochytrium.
