Cited by 176Algal biology and biofuel productionMicrobial Metabolic Engineering and BioproductionLipid metabolism and biosynthesis

Oil accumulation mechanisms of the oleaginous microalga Chlorella protothecoides revealed through its genome, transcriptomes, and proteomes

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Gao, Chunfang, Wang, Yun, Shen, Yue, Yan, Dong, He, Xi, Dai, Junbiao, Wu, Qingyu·2014·BMC Genomics

Abstract

BACKGROUND: Microalgae-derived biodiesel is a promising substitute for conventional fossil fuels. In particular, the green alga Chlorella protothecoides sp. 0710 is regarded as one of the best candidates for commercial manufacture of microalgae-derived biofuel. This is due not only to its ability to live autotrophically through photosynthesis, but also to its capacity to produce a large amount of biomass and lipid through fermentation of glucose. However, until the present study, neither its genome sequence nor the platform required for molecular manipulations were available. RESULTS: We generated a draft genome for C. protothecoides, and compared its genome size and gene content with that of Chlorella variabilis NC64A and Coccomyxa subellipsoidea C-169. This comparison revealed that C. protothecoides has a reduced genome size of 22.9 Mbp, about half that of its close relatives. The C. protothecoides genome encodes a smaller number of genes, fewer multi-copy genes, fewer unique genes, and fewer genome rearrangements compared with its close relatives. In addition, three Chlorella-specific hexose-proton symporter (HUP)-like genes were identified that enable the consumption of glucose and, consequently, heterotrophic growth. Furthermore, through comparative transcriptomic and proteomic studies, we generated a global perspective regarding the changes in metabolic pathways under autotrophic and heterotrophic growth conditions. Under heterotrophic conditions, enzymes involved in photosynthesis and CO2 fixation were almost completely degraded, either as mRNAs or as proteins. Meanwhile, the cells were not only capable of quickly assimilating glucose but also showed accelerated glucose catabolism through the upregulation of glycolysis and the tricarboxylic acid (TCA) cycle. Moreover, the rapid synthesis of pyruvate, upregulation of most enzymes involved in fatty acid synthesis, and downregulation of enzymes involved in fatty acid degradation favor the synthesis of fatty acids within the cell. CONCLUSIONS: Despite similarities to other Chlorella, C. protothecoides has a smaller genome than its close relatives. Genes involved in glucose utilization were identified, and these genes explained its ability to grow heterotrophically. Transcriptomic and proteomic results provided insight into its extraordinary ability to accumulate large amounts of lipid. The C. protothecoides draft genome will promote the use of this species as a research model.

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Authors
Gao, C., Wang, Y., Shen, Y., Yan, D., He, X., Dai, J., & Wu, Q.
Affiliations
  • China People's Public Security University (CN)
  • BGI Group (China) (CN)
  • Tsinghua University (CN)
Corresponding author
  • Dai, Junbiao
  • Wu, Qingyu
Venue
BMC Genomics
Published
2014-07-10
Volume
15
Issue
1
Pages
582-582
ISSN
1471-2164 (ISSN-L)
OpenAlex
W1984532384
Cited by
175
References
65
Citations by year
2026: 5 · 2025: 9 · 2024: 15 · 2023: 10 · 2022: 14 · 2021: 17 · 2020: 16 · 2019: 25 · 2018: 18 · 2017: 16 · 2016: 18 · 2015: 7 · 2014: 5
FWCI
5.06
Type
journal article
Language
en
Open access
Licence
cc-by
Locations
  • BMC Genomics (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
Funders
  • National Natural Science Foundation of China (41030210, 31370282)
  • Tsinghua University (2012Z08128)
Topics
  • Physical Sciences › Energy › Renewable Energy, Sustainability and the Environment › Algal biology and biofuel production
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Microbial Metabolic Engineering and Bioproduction
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Biochemistry › Lipid metabolism and biosynthesis
Keywords
Chlorella protothecoides, lipid accumulation, draft genome sequence, genome size reduction, comparative genomics, heterotrophic growth, autotrophic growth, glucose catabolism, glycolysis, TCA cycle, fatty acid synthesis, Chlorella variabilis
MeSH terms
Carbon, Chlorella, Citric Acid Cycle, Energy Metabolism, Glycolysis, Plant Oils, Genome, Plant, Proteome, Metabolic Networks and Pathways, Comparative Genomic Hybridization, Biofuels, Transcriptome

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