Identification of small droplets of photosynthetic squalene in engineered Synechococcus elongatus PCC 7942 using TEM and selective fluorescent Nile red analysis

S. Y. Choi, S. J. Sim, J. I. Choi, H. M. Woo

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    6 Citations (Scopus)

    Abstract

    To identify microbial squalene that has been widely used in various industrial applications, intracellular formation of photosynthetic squalene was investigated using the previously engineered Synechococcus elongatusPCC 7942 strain. Unlike the proposed localization of squalene in the membrane bilayer, small droplets were identified in the cytoplasm of S. elongatusPCC 7942 as squalene using transmission electron microscopy analysis. Determination of the diameters of the squalene droplets with manual examination of 1016 droplets in different squalene-producing strains indicated larger squalene droplets in larger cells. Based on the observation of a sole droplet of squalene in a cyanobacterium, fluorescent Nile red was used for the selective staining of squalene. The fluorescent intensities were correlated with squalene contents determined using gas chromatography-mass spectrometry. Photosynthetic squalene was identified as a small droplet in S. elongatusPCC 7942, and this noninvasive quantitative method could be useful to promote high-throughput strain development for squalene production. Significance and Impact of the Study: Engineering of Cyanobacteria has focused on sustainable production of squalene by converting CO2. Before improving the photosynthetic squalene production, we characterized formation of squalene, showing small droplets in the cytoplasm instead of single granule. Based on the finding and the analysis, this study has provided valuable evidences how further metabolic engineering strategies should apply to enhance the production yield.

    Original languageEnglish
    Pages (from-to)523-529
    Number of pages7
    JournalLetters in Applied Microbiology
    Volume66
    Issue number6
    DOIs
    Publication statusPublished - 2018 Jun

    Bibliographical note

    Funding Information:
    The authors thank M.S. So Hee Kwon and M.S. Geun-Ae Jang at Seoul National University for their technical support. This work was supported by Korea CCS R&D Center (KCRC) (2017M1A8A1072034) and Basic Science Research Program (2017R1A2B2002566) through the National Research Foundation of Korea, funded by the Korean Government (Ministry of Science and ICT). In addition, this work was partially supported by the Golden Seed Project (213008-05-2-WT911) grant, funded by the Ministry of Agriculture and the Ministry of Oceans and Fisheries.

    Publisher Copyright:
    © 2018 The Society for Applied Microbiology

    Keywords

    • Cyanobacteria
    • bioproducts
    • biotechnology
    • microbial physiology
    • microbial structure

    ASJC Scopus subject areas

    • Applied Microbiology and Biotechnology

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