Low-phosphate-selected auxenochlorella protothecoides redirects phosphate to essential pathways while producing more biomass

Sang Hyuck Park, John Kyndt, Kapeel Chougule, Jeong Jin Park, Judith K Brown

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Despite the capacity to accumulate ~70% w/w of lipids, commercially produced unicellular green alga A. protothecoides may become compromised due to the high cost of phosphate fertilizers. To address this limitation A. protothecoides was selected for adaptation to conditions of 100× and 5× lower phosphate and peptone, respectively, compared to ‘wild-type media’. The A. protothecoides showed initial signs of adaptation by 45–50 days, and steady state growth at ~100 days. The low phosphate (P)-adapted strain produced up to ~30% greater biomass, while total lipids (~10% w/w) remained about the same, compared to the wild-type strain. Metabolomic analyses indicated that the low P-adapted produced 3.3-fold more saturated palmitic acid (16:0) and 2.2-fold less linolenic acid (18:3), compared to the wild-type strain, resulting in an ~11% increase in caloric value, from 19.5kJ/g for the wild-type strain to 21.6kJ/g for the low P-adapted strain, due to the amounts and composition of certain saturated fatty acids, compared to the wild type strain. Biochemical changes in A. protothecoides adapted to lower phosphate conditions were assessed by comparative RNA-Seq analysis, which yielded 27,279 transcripts. Among them, 2,667 and 15 genes were significantly down- and up-regulated, at >999-fold and >3-fold (adjusted p-value <0.1), respectively. The expression of genes encoding proteins involved in cellular processes such as division, growth, and membrane biosynthesis, showed a trend toward down-regulation. At the genomic level, synonymous SNPs and Indels were observed primarily in coding regions, with the 40S ribosomal subunit gene harboring substantial SNPs. Overall, the adapted strain out-performed the wild-type strain by prioritizing the use of its limited phosphate supply for essential biological processes. The low P-adapted A. protothecoides is expected to be more economical to grow over the wild-type strain, based on overall greater productivity and caloric content, while importantly, also requiring 100-fold less phosphate.

Original languageEnglish (US)
Article numbere0198953
JournalPLoS One
Volume13
Issue number6
DOIs
StatePublished - Jun 1 2018

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Biomass
Phosphates
phosphates
biomass
Single Nucleotide Polymorphism
Eukaryotic Small Ribosome Subunits
Biological Phenomena
Lipids
Peptones
Chlorophyta
alpha-Linolenic Acid
Metabolomics
Palmitic Acid
Fertilizers
Growth
Genes
Phosphate fertilizers
Auxenochlorella protothecoides
Gene encoding
Fatty Acids

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Agricultural and Biological Sciences(all)

Cite this

Low-phosphate-selected auxenochlorella protothecoides redirects phosphate to essential pathways while producing more biomass. / Park, Sang Hyuck; Kyndt, John; Chougule, Kapeel; Park, Jeong Jin; Brown, Judith K.

In: PLoS One, Vol. 13, No. 6, e0198953, 01.06.2018.

Research output: Contribution to journalArticle

Park, Sang Hyuck ; Kyndt, John ; Chougule, Kapeel ; Park, Jeong Jin ; Brown, Judith K. / Low-phosphate-selected auxenochlorella protothecoides redirects phosphate to essential pathways while producing more biomass. In: PLoS One. 2018 ; Vol. 13, No. 6.
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