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  • Wiley  (2)
  • 2015-2019  (2)
  • 1
    Online Resource
    Online Resource
    A novel source of dihomo‐γ‐linolenic acid: Possibilities and limitations of DGLA production in the high‐density cultures of the Δ5 desaturase‐mutant microalga Lobosphaera incisa
    Wiley ; 2015
    In:  European Journal of Lipid Science and Technology Vol. 117, No. 6 ( 2015-06), p. 760-766
    Details
    In: European Journal of Lipid Science and Technology, Wiley, Vol. 117, No. 6 ( 2015-06), p. 760-766
    Abstract: The Δ5 desaturase mutant (P127) of the microalga Lobosphaera incisa is a promising organism for large‐scale production of the valuable LC‐PUFA dihomo‐γ‐linolenic acid (DGLA, 20:3 n ‐6). We examined the potential of P127 for DGLA production under nitrogen (N) starvation conditions, triggering the deposition of DGLA in triacylglycerols, and developed a strategy for optimization of the DGLA productivity in high‐density cultures. Towards this end, the effects of initial biomass concentration (1, 2, and 4 g L −1 ) and PAR irradiance (170 and 400 µmol m −2 s −1 ) on DGLA and total fatty acid (TFA) production were studied. The highest DGLA and TFA percentages (10 and 38% of dry weight, respectively) were displayed by the cultures initiated at 1 g L −1 and grown under a moderate irradiance. Higher irradiances and lower starting biomass content facilitated oleic acid accumulation at the expense of DGLA. Maximum volumetric productivities of TFA and DGLA were recorded in the cultures started at 2 g L −1 biomass and grown under 400 μmol PAR m −2 s −1 . We show that a sufficiently high starting culture density should be combined with a mild light stress to facilitate the production of biomass enriched in DGLA‐containing triacylglycerols. Practical applications The ∆5 desaturase mutant of L. incisa , P127, is a rare green source of DGLA, a LC‐PUFA with valuable pharmaceutical and neutraceutical properties. We report on the optimization of DGLA production by the nitrogen‐starving indoor cultures of P127. Stresses, such as N starvation and/or high irradiances, promote accumulation of lipids by microalgal cells. On the other hand, excessively severe stress is deteriorative for the target LC‐PUFA accumulation. An important outcome of the present work is establishing physiological constrains of DGLA productivity and finding an approach to balance starting cell density vs. irradiance in order to maximize DGLA yields. Findings of the present work lay a foundation of the efficient production of DGLA using upscaled cultures of P127. High productivity of DGLA‐enriched biomass by P127 under nitrogen starvation is attainable by combining relatively high starting culture density with a mild light stress. By contrast, high irradiances impair DGLA accumulation in the cultures initiated at the biomass content of ≤ 1 gL −1 .
    Type of Medium: Online Resource
    ISSN: 1438-7697 , 1438-9312
    URL: Issue
    URL: Article
    DOI: 10.1002/ejlt.v117.6
    DOI: 10.1002/ejlt.201400430
    Language: English
    Publisher: Wiley
    Publication Date: 2015
    detail.hit.zdb_id: 2012720-0
    SSG: 21
    Location Call Number Limitation Availability
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  • 2
    Online Resource
    Online Resource
    Cloning, molecular characterization, and phylogeny of two evolutionary distinct glutamine synthetase isoforms in the green microalga Haematococcus pluvialis (Chlorophyceae)
    Wiley ; 2016
    In:  Journal of Phycology Vol. 52, No. 6 ( 2016-12), p. 961-972
    Details
    In: Journal of Phycology, Wiley, Vol. 52, No. 6 ( 2016-12), p. 961-972
    Abstract: Haematococcus pluvialis (Chlorophyta) is a widely used microalga of great economic potential, yet its molecular genetics and evolution are largely unknown. We present new detailed molecular and phylogenetic analysis of two glutamine synthetase ( GS ) enzymes and genes ( gln ) under the Astaxanthin‐inducing conditions of light‐ and nitrogen‐stress. Structure analysis identified key residues and confirmed two decameric GS 2 holoenzymes, a cytoplasmic enzyme, termed GS 2c , and a plastidic form, termed GS 2p , due to chloroplast‐transit peptides at its N‐terminus. Gene expression analysis showed dissociation of mRNA , protein, and enzyme activity levels for both GS 2 under different growth conditions, indicating the strong post‐transcriptional regulation. Data‐mining identified novel and specified published gln genes from Prasinophyceae, Chlorophyta, Trebouxiophyceae, Charophyceae, Bryophyta, Lycopodiophyta, Spermatophyta, and Rhodophyta. Phylogenetic analysis found homologues to the cytosolic GS 2c of H. pluvialis in all other photo‐ and non‐photosynthetic Eukaryota. The chloroplastic GS 2p was restricted to Chlorophyta, Bryophyta, some Proteobacteria and Fungii; no homologues were identified in Spermatophyta or other Eukaryota. This indicates two independent prokaryotic donors for these two gln genes in H. pluvialis . Combined phylogenetic analysis of GS , chl‐ b synthase, elongation factor, and light harvesting complex homologues project a newly refined model of Viridiplantae evolution. Herein, a GS 1 evolved into the cytosolic GS 2c and was passed on to all Eukaryota. Later, the chloroplastic GS 2p entered the Archaeplastida lineage via a horizontal gene transfer at the divergence of Chlorophyta and Rhodophyta lineages. GS 2p persisted in Chlorophyta and Bryophyta, but was lost during Spermatophyta evolution. These data suggest the revision of GS classification and nomenclature, and extend our understanding of the photosynthetic Eukaryota evolution.
    Type of Medium: Online Resource
    ISSN: 0022-3646 , 1529-8817
    URL: Issue
    URL: Article
    DOI: 10.1111/jpy.2016.52.issue-6
    DOI: 10.1111/jpy.12444
    RVK:
    WA 15000
    Language: English
    Publisher: Wiley
    Publication Date: 2016
    detail.hit.zdb_id: 281226-5
    detail.hit.zdb_id: 1478748-9
    SSG: 12
    Location Call Number Limitation Availability
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