Microalgal lipid droplets: composition, diversity, biogenesis and functions

Goold, Hugh D.; Beisson, Fred; Peltier, Gilles; Li‐Beisson, Yonghua

doi:10.1007/s00299-014-1711-7

Cited by 116 publications

(107 citation statements)

References 84 publications

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“…To demonstrate the utility of the library, we used a candidatebased approach to identify genes involved in accumulation of the storage lipid TAG, which accumulates in organelles called lipid droplets (Goold et al, 2015). In both animals and plants, several proteins that impact TAG synthesis or degradation were found to (A) LEAP-Seq reads are used to identify cases where there is a short insertion of genomic DNA from another locus (designated "junk" DNA) between the cassette and the flanking genomic DNA.…”

Section: We Used the Leap-seq-confirmed Library To Characterize Mutanmentioning

confidence: 99%

An Indexed, Mapped Mutant Library Enables Reverse Genetics Studies of Biological Processes in Chlamydomonas reinhardtii

et al. 2016

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The green alga Chlamydomonas reinhardtii is a leading unicellular model for dissecting biological processes in photosynthetic eukaryotes. However, its usefulness has been limited by difficulties in obtaining mutants in specific genes of interest. To allow generation of large numbers of mapped mutants, we developed high-throughput methods that (1) enable easy maintenance of tens of thousands of Chlamydomonas strains by propagation on agar media and by cryogenic storage, (2) identify mutagenic insertion sites and physical coordinates in these collections, and (3) validate the insertion sites in pools of mutants by obtaining >500 bp of flanking genomic sequences. We used these approaches to construct a stably maintained library of 1935 mapped mutants, representing disruptions in 1562 genes. We further characterized randomly selected mutants and found that 33 out of 44 insertion sites (75%) could be confirmed by PCR, and 17 out of 23 mutants (74%) contained a single insertion. To demonstrate the power of this library for elucidating biological processes, we analyzed the lipid content of mutants disrupted in genes encoding proteins of the algal lipid droplet proteome. This study revealed a central role of the long-chain acyl-CoA synthetase LCS2 in the production of triacylglycerol from de novo-synthesized fatty acids.

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Section: We Used the Leap-seq-confirmed Library To Characterize Mutanmentioning

confidence: 99%

An Indexed, Mapped Mutant Library Enables Reverse Genetics Studies of Biological Processes in Chlamydomonas reinhardtii

et al. 2016

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“…LDs are specialized intracellular organelles made of a neutral lipid core surrounded by a membrane lipid coat in which proteins are embedded (Huang, 1996). LDs serve as a temporary storage site for neutral lipids and also participate in the active synthesis and metabolism of these non-membrane-forming lipids (Goodman, 2008;Farese and Walther, 2009;Chapman et al, 2012;Goold et al, 2015;Tsai et al, 2015). The current model of LD biogenesis suggests that these lipid-rich subcellular structures arise from membrane budding or blistering; thus, the lipid molecules present in the LD lipid coat suggest its origin of biogenesis.…”

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confidence: 99%

“…Thus, the protein and lipid composition of LDs can shed light on the likely subcellular location of TAG synthesis and LD biogenesis. Compared with oilseeds, the unicellular microalga C. reinhardtii offers an excellent platform in which to study LD formation, due to the ease with which researchers can induce LD biogenesis or degradation by simply changing the culture medium (Goodson et al, 2011;Goold et al, 2015;Tsai et al, 2015).…”

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confidence: 99%

Saturating Light Induces Sustained Accumulation of Oil in Plastidal Lipid Droplets in Chlamydomonas reinhardtii

et al. 2016

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Enriching algal biomass in energy density is an important goal in algal biotechnology. Nitrogen (N) starvation is considered the most potent trigger of oil accumulation in microalgae and has been thoroughly investigated. However, N starvation causes the slow down and eventually the arrest of biomass growth. In this study, we show that exposing a Chlamydomonas reinhardtii culture to saturating light (SL) under a nonlimiting CO 2 concentration in turbidostatic photobioreactors induces a sustained accumulation of lipid droplets (LDs) without compromising growth, which results in much higher oil productivity than N starvation. We also show that the polar membrane lipid fraction of SL-induced LDs is rich in plastidial lipids (approximately 70%), in contrast to N starvation-induced LDs, which contain approximately 60% lipids of endoplasmic reticulum origin. Proteomic analysis of LDs isolated from SL-exposed cells identified more than 200 proteins, including known proteins of lipid metabolism, as well as 74 proteins uniquely present in SL-induced LDs. LDs induced by SL and N depletion thus differ in protein and lipid contents. Taken together, lipidomic and proteomic data thus show that a large part of the sustained oil accumulation occurring under SL is likely due to the formation of plastidial LDs. We discuss our data in relation to the different metabolic routes used by microalgae to accumulate oil reserves depending on cultivation conditions. Finally, we propose a model in which oil accumulation is governed by an imbalance between photosynthesis and growth, which can be achieved by impairing growth or by boosting photosynthetic carbon fixation, with the latter resulting in higher oil productivity.

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“…Within the microalgae cell, lipid droplets (LD) are the major site of neutral lipid storage (Goold et al 2014) and additionally contain valuable products such as carotenoids and pigments. Under nitrogen-replete conditions, green microalgae contain one or two lipid droplets but LD synthesis and accumulation are activated in the presence of stress conditions including nutrient depletion (-N, -Fe, -S, -P), high light, hypoxia, increased salinity, or chemical application (Wang et al 2009).…”

Section: Lipid Droplet Structure and Disruption Strategiesmentioning

confidence: 99%

Green microalgae biomolecule separations and recovery

Dixon

Wilken

2018

Bioresour. Bioprocess.

109

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Microalgae biomass has garnered significant attention as a renewable energy feedstock and alternative to petroleumbased fuels. The diverse metabolism of green microalgae species additionally provides opportunities for recovery of products for feed, food, nutraceutical, cosmetic, and biopharmaceutical industries. Recently, the concept of using microalgae as part of a biorefinery model has been adopted in place of refinery methods focused on recovering one target product. This has led to producers exploring co-production of high value and high volume products in an effort to improve process economics. With numerous potential products and applications, the biomass source or specific strain must be carefully selected to accumulate extractable levels of the target molecule(s). It is additionally imperative to understand the morphology and metabolism of the selected strain to cost-effectively manage all stages of commercial production. This review will focus specifically on microalgae in the division of Chlorophyta, or green algae and their extracellular matrices (ECM), potential for commercial products, and finally describe a holistic approach for biomolecule extraction and recovery. Additionally, cell disruption and fractionation methods for recovery of biomolecules for commercial products are highlighted along with an alternative method, aqueous enzymatic processing for multiple biomolecule extraction and recovery from green microalgae. An emphasis is placed on connecting the morphological characteristics of microalgae ECM or organelle membranes to implications on separation and purification technologies.

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Microalgal lipid droplets: composition, diversity, biogenesis and functions

Cited by 116 publications

References 84 publications

An Indexed, Mapped Mutant Library Enables Reverse Genetics Studies of Biological Processes in Chlamydomonas reinhardtii

An Indexed, Mapped Mutant Library Enables Reverse Genetics Studies of Biological Processes in Chlamydomonas reinhardtii

Saturating Light Induces Sustained Accumulation of Oil in Plastidal Lipid Droplets in Chlamydomonas reinhardtii

Green microalgae biomolecule separations and recovery

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