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. 2015 Aug 6;3(4):e00819-15. doi: 10.1128/genomeA.00819-15

Genome Sequence of Schizochytrium sp. CCTCC M209059, an Effective Producer of Docosahexaenoic Acid-Rich Lipids

Xiao-Jun Ji a, Kai-Qiang Mo a, Lu-Jing Ren a, Gan-Lu Li a, Jian-Zhong Huang b, He Huang a,
PMCID: PMC4541280  PMID: 26251485

Abstract

Schizochytrium is an effective species for producing omega-3 docosahexaenoic acid (DHA). Here, we report a genome sequence of Schizochytrium sp. CCTCC M209059, which has a genome size of 39.09 Mb. It will provide the genomic basis for further insights into the metabolic and regulatory mechanisms underlying the DHA formation.

GENOME ANNOUNCEMENT

Docosahexaenoic acid (DHA), one of the most typical omega-3 polyunsaturated fatty acids, has received worldwide attention due to its beneficial physiological functions for humans (1, 2). Its traditional sources are coldwater fish oils. However, the product quality derived from fish oil is dependent on season and position and is affected by ocean pollution. Alternatively, DHA can be obtained from marine fungal oils (lipids).

Schizochytrium sp., which was first derived from coastal seawater as a new thraustochytrid by Nakahara et al. (3), has been widely used to produce DHA. It can accumulate up to 50% of its dry weight as lipids, DHA generally constituting 40% or more of these (4). However, the physiological role of DHA to Schizochytrium sp. cells has not been elucidated clearly. DHA, in the form of membrane phospholipids, is generally known to play an important role in membrane functions (5). However, only up to 5% of lipids in Schizochytrium sp. occur as phospholipids, whereas 90% or more are generally present as triacylglycerols in storage lipids (68). Why do Schizochytrium sp. cells accumulate more DHA as triacylglycerols instead of as phospholipids? The reason for this is not clear. Furthermore, in Schizochytrium spp., the metabolic pathway for DHA biosynthesis (via polyketide synthases) is different from the pathway in other DHA-producing strains (via fatty acid synthases), such as Thraustochytrium spp., Crypthecodinium cohnii, and so on (911).

We therefore sequenced and analyzed the genome of Schizochytrium sp. CCTCC M209059, which is an efficient DHA-producing strain stored in the China Center for Type Culture Collection (12, 13), to reveal the metabolic and regulatory mechanisms underlying the DHA formation, both in relation to its physiological functions and its distinctive metabolic pathways.

The genomic DNA of the strain was isolated using the EZNA fungal DNA kit (Omega Bio-tek, Doraville, GA, USA). The purity and concentration of the DNA were measured by a Qubit Fluorometer (Invitrogen, Carlsbad, CA, USA). Genome sequencing was conducted using the Illumina HiSeq2000 DNA sequencing platform at BGI-Shenzhen (Shenzhen, China). The raw sequence data comprise a total of 61,950,544 reads, assembled into 1,608 contigs through the SOAPdenovo alignment tool (14, 15). The genome assembly is 38,297,968 bp, with an N50 equal to 52,007 bp, an N90 of 14,718 bp, and a maximum contig size of 236,430 bp. The contigs were further scaffolded with a total of 39,089,698 bp, which were placed in the final 322 scaffolds, with an N50 of 595,797 bp, an N90 of 144,465 bp, and a maximum scaffold size of 1,674,554 bp. This resulted in a predicted genome size of 39.09 Mb with a G+C content of 56.6%. There are a total of 9,142 predicted protein-coding genes, 178 tRNA genes, and 31 rRNA genes in the genome. Annotation of the genome was performed via Gene Ontology Analysis (16) and the Kyoto Encyclopedia of Genes and Genomes pathway database (17). The genome sequence could provide opportunities for investigating the metabolic and regulatory mechanisms underlying the formation of DHA, which will provide guidance for efficient DHA production with high content and high productivity.

Nucleotide sequence accession numbers.

This whole-genome shotgun project has been deposited at DDBJ/EMBL/GenBank under the accession number JTFK00000000.The version described in this paper is the first version, JTFK01000000.

ACKNOWLEDGMENTS

This work was financially supported by the National Science Foundation for Distinguished Young Scholars of China (grant 21225626), the National Natural Science Foundation of China (grants 21306085, 21376002, and 21476111), the Jiangsu Provincial Natural Science Foundation (grants BK2012424 and BK20131405), the National High-Tech R&D Program of China (grants 2012AA021704 and 2014AA021701), and the Priority Academic Program Development of Jiangsu Higher Education Institutions.

Footnotes

Citation Ji X-J, Mo K-Q, Ren L-J, Li G-L, Huang J-Z, Huang H. 2015. Genome sequence of Schizochytrium sp. CCTCC M209059, an effective producer of docosahexaenoic acid-rich lipids. Genome Announc 3(4):e00819-15. doi:10.1128/genomeA.00819-15.

REFERENCES

  • 1.Gupta A, Barrow CJ, Puri M. 2012. Omega-3 biotechnology: thraustochytrids as a novel source of omega-3 oils. Biotechnol Adv 30:1733–1745. doi: 10.1016/j.biotechadv.2012.02.014. [DOI] [PubMed] [Google Scholar]
  • 2.Horrocks LA, Yeo YK. 1999. Health benefits of docosahexaenoic acid (DHA). Pharmacol Res 40:211–225. doi: 10.1006/phrs.1999.0495. [DOI] [PubMed] [Google Scholar]
  • 3.Nakahara T, Yokochi T, Higashihara T, Tanaka S, Yaguchi T, Honda D. 1996. Production of docosahexaenoic and docosapentaenoic acids by Schizochytrium sp. isolated from Yap Islands. J Am Oil Chem Soc 11:1421–1426. [Google Scholar]
  • 4.Singh A, Ward OP. 1997. Microbial production of docosahexaenoic acid (DHA, C22:6). Adv Appl Microbiol 45:271–312. doi: 10.1016/S0065-2164(08)70266-1. [DOI] [PubMed] [Google Scholar]
  • 5.Stillwell W, Wassall SR. 2003. Docosahexaenoic acid: membrane properties of a unique fatty acid. Chem Phys Lipids 126:1–27. doi: 10.1016/S0009-3084(03)00101-4. [DOI] [PubMed] [Google Scholar]
  • 6.Ashford A, Barclay WR, Weaver CA, Giddings TH, Zeller S. 2000. Electron microscopy may reveal structure of docosahexaenoic acid-rich oil within Schizochytrium sp. Lipids 35:1377–1386. doi: 10.1007/s11745-000-0655-2. [DOI] [PubMed] [Google Scholar]
  • 7.Ren LJ, Sun GN, Ji XJ, Hu XC, Huang H. 2014. Compositional shift in lipid fractions during lipid accumulation and turnover in Schizochytrium sp. Bioresour Technol 157:107–113. doi: 10.1016/j.biortech.2014.01.078. [DOI] [PubMed] [Google Scholar]
  • 8.Sun LN, Ren LJ, Zhuang XY, Ji XJ, Yan JC, Huang H. 2014. Differential effects of nutrient limitations on biochemical constituents and docosahexaenoic acid production of Schizochytrium sp. Bioresour Technol 159:199–206. doi: 10.1016/j.biortech.2014.02.106. [DOI] [PubMed] [Google Scholar]
  • 9.Ji XJ, Ren LJ, Nie ZK, Huang H, Ouyang PK. 2014. Fungal arachidonic acid-rich oil: research, development and industrialization. Crit Rev Biotechnol 34:197–214. doi: 10.3109/07388551.2013.778229. [DOI] [PubMed] [Google Scholar]
  • 10.Metz JG, Kuner J, Rosenzweig B, Lippmeier JC, Roessler P, Zirkle R. 2009. Biochemical characterization of polyunsaturated fatty acid synthesis in Schizochytrium: release of the products as free fatty acids. Plant Phy Biol Chem 47:472–478. doi: 10.1016/j.plaphy.2009.02.002. [DOI] [PubMed] [Google Scholar]
  • 11.Metz JG, Roessler P, Facciotti D, Levering C, Dittrich F, Lassner M, Valentine R, Lardizabal K, Domergue F, Yamada A, Yazawa K, Knauf V, Browse J. 2001. Production of polyunsaturated fatty acids by polyketide synthases in both prokaryotes and eukaryotes. Science 293:290–295. doi: 10.1126/science.1059593. [DOI] [PubMed] [Google Scholar]
  • 12.Huang H, Ren LJ, Xiao AH, Jin LJ, Li J. 2009. A kind of Schizochytrium sp. and the method for DHA-rich oil production using thereof. Chinese patent ZL 200910033869.5.
  • 13.Ren LJ, Ji XJ, Huang H, Qu L, Feng Y, Tong QQ, Ouyang PK. 2010. Development of a stepwise aeration control strategy for efficient docosahexaenoic acid production by Schizochytrium sp. Appl Microbiol Biotechnol 87:1649–1656. doi: 10.1007/s00253-010-2639-7. [DOI] [PubMed] [Google Scholar]
  • 14.Li R, Li Y, Kristiansen K, Wang J. 2008. SOAP: short oligonucleotide alignment program. Bioinformatics 24:713–714. doi: 10.1093/bioinformatics/btn025. [DOI] [PubMed] [Google Scholar]
  • 15.Li R, Zhu H, Ruan J, Qian W, Fang X, Shi Z, Li Y, Li S, Shan G, Kristiansen K, Li S, Yang H, Wang J, Wang J. 2010. De novo assembly of human genomes with massively parallel short read sequencing. Genome Res 20:265–272. doi: 10.1101/gr.097261.109. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 16.Tatusov RL, Galperin MY, Natale DA, Koonin EV. 2000. The COG database: a tool for genome-scale analysis of protein functions and evolution. Nucleic Acids Res 28:33–36. doi: 10.1093/nar/28.1.33. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 17.Ogata H, Goto S, Sato K, Fujibuchi W, Bono H, Kanehisa M. 1999. KEGG: Kyoto encyclopedia of genes and genomes. Nucleic Acids Res 27:29–34. doi: 10.1093/nar/27.1.29. [DOI] [PMC free article] [PubMed] [Google Scholar]

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