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Understanding and controlling biological systems
AlgAdvance

AlgAdvance

New strategies for developing microalgae as a renewable resource for biofuels.

Oily microalgae are a source of biomass rich in oil, a class of energetically dense molecules that can be valuable for various industrial sectors, including health and cosmetics, commodity chemicals, and biofuels.

Algae-based biofuels within the circular carbon economy are promising for capturing CO₂ emissions from industry and converting it into energetically dense molecules (oils). However, this application faces technological barriers, such as biomass productivity and oil content, energy consumption of these processes, and conversion to biofuels. Societal and industrial acceptance of optimizing strains through genetic engineering is also a central issue in these developments.

Project objectives

Carbon distribution:

Generate knowledge on the acquisition and distribution of carbon by algae, lipid metabolism, cell division, and stress resistance.

Genetic development:

Develop non-GMO algal strains (including Crispr-Cas9 editing approaches without retaining exogenous DNA, polyploidization, and random mutagenesis).

Performance:

Develop strategies to control the performance limits of strains transferred to the pilot scale, focusing on the coupling of cultivation and extraction processes and adaptation to outdoor cultivation.

Analysis cycle:

Conduct laboratory-to-pilot and pilot-to-laboratory analysis cycles to better address biological and process limitations (TRL1 to TRL4).

Intellectual property:

Secure intellectual property and support industry transfers.

Algadvance - Micro-algues et piscines

 

 

Project lifetime:
 

February 2023 - February 2029

 

Scientific manager:
 

Eric Maréchal (CNRS)

 

The consortium:
 

Higher education establishment
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Research institutes
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Research units involved
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Titre-image Publications

HAL : Dernières publications

  • [hal-04964370] Light, CO2, and carbon storage in microalgae

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    ano.nymous@ccsd.cnrs.fr.invalid (Yasuyo Yamaoka) 24 Feb 2025

    https://hal.science/hal-04964370v1
  • [hal-04463739] Phototropin connects blue light perception to starch metabolism in green algae

    In photosynthetic organisms light acts as an environmental signal to control their development and physiology, and as energy source to drive the conversion of CO 2 into carbohydrates used for growth or storage. The main storage carbohydrate in green algae is starch, which accumulates during the day and is broken down at night to meet cellular energy demands. The signalling role of light quality in the regulation of starch accumulation remains unexplored. Here, we report that in the model green alga Chlamydomonas reinhardtii blue light perceived by the photoreceptor PHOTOTROPIN causes dephosphorylation of the PHOTOTROPIN-MEDIATED SIGNALLING KINASE 1 that then suppresses starch accumulation by inhibiting the expression of GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE. Our results provide an in-depth view of how photoreceptor-mediated signalling controls microalgal carbon metabolism. One-Sentence Summary Blue light perception by PHOTOTROPIN triggers kinase-mediated signaling to inhibit starch accumulation in the green alga Chlamydomonas .

    ano.nymous@ccsd.cnrs.fr.invalid (Yizhong Yuan) 17 Mar 2025

    https://hal.science/hal-04463739v1
  • [hal-04738744] The DYRKP1 kinase regulates cell wall degradation in Chlamydomonas by inducing matrix metalloproteinase expression

    The cell wall of plants and algae is an important cell structure that protects cells from changes in the external physical and chemical environment. This extracellular matrix, composed of polysaccharides and glycoproteins, must be constantly remodeled throughout the life cycle. However, compared to matrix polysaccharides, little is known about the mechanisms regulating the formation and degradation of matrix glycoproteins. We report here that a plant kinase belonging to the DUAL-SPECIFICITY TYROSINE PHOSPHORYLATION-REGULATED KINASE (DYRK) family present in all eukaryotes regulates cell wall degradation after mitosis of Chlamydomonas reinhardtii by inducing the expression of matrix metalloproteinases (MMPs). Without the plant DYRK kinase (DYRKP1), daughter cells cannot disassemble parental cell walls and remain trapped inside for more than 10 days. On the other hand, the DYRKP1 complementation line shows normal degradation of the parental cell wall. Transcriptomic and proteomic analyses indicate a marked down-regulation of MMP gene expression and accumulation, respectively, in the dyrkp1 mutants. The mutants deficient in MMPs retain palmelloid structures for a longer time than the background strain, like dyrkp1 mutants. Our findings show that DYRKP1, by ensuring timely MMP expression, enables the successful execution of the cell cycle. Altogether, this study provides insight into the life cycle regulation in plants and algae.

    ano.nymous@ccsd.cnrs.fr.invalid (Minjae Kim) 25 Jan 2025

    https://hal.science/hal-04738744v1
  • [hal-04703221] Knocking out the carboxyltransferase interactor 1 (CTI1) in Chlamydomonas boosted oil content by fivefold without affecting cell growth

    ABSTRACT The first step in chloroplast de novo fatty acid synthesis is catalyzed by acetyl-CoA carboxylase (ACCase). As the rate-limiting step for this pathway, ACCase is subject to both positive and negative regulation. In this study, we identify a Chlamydomonas homolog of the plant carboxyltransferase interactor 1 (CrCTI1) and show that this protein, interacts with the Chlamydomonas α-carboxyltransferase (Crα-CT) subunit of the ACCase by yeast two-hybrid protein-protein interaction assay. Three independent CRISPR-Cas9 mediated knock-out mutants for CrCTI1 each produced an “enhanced oil” phenotype, accumulating 25% more total fatty acids and storing up to five-fold more triacylglycerols (TAGs) in lipid droplets. The TAG phenotype of the crcti1 mutants was not influenced by light but was affected by trophic growth conditions. By growing cells under heterotrophic conditions, we observed a crucial function of CrCTI1 in balancing lipid accumulation and cell growth. Mutating a previously mapped in vivo phosphorylation site (CrCTI1 Ser108 to either Ala or to Asp), did not affect the interaction with Crα-CT. However, mutating all six predicted phosphorylation sites within Crα-CT to create a phosphomimetic mutant reduced significantly this pairwise interaction. Comparative proteomic analyses of the crcti1 mutants and WT suggested a role for CrCTI1 in regulating carbon flux by coordinating carbon metabolism, antioxidant and fatty acid β-oxidation pathways, to enable cells adapt to carbon availability. Taken together, this study identifies CrCTI1 as a negative regulator of fatty acid synthesis in algae and provides a new molecular brick for genetic engineering of microalgae for biotechnology purposes.

    ano.nymous@ccsd.cnrs.fr.invalid (Zhongze Li) 20 Sep 2024

    https://hal.science/hal-04703221v1
  • [hal-04281075] Dryland endolithic Chroococcidiopsis and temperate fresh water Synechocystis have distinct membrane lipid and photosynthesis acclimation strategies upon desiccation and temperature increase

    An effect of climate change is the expansion of drylands in temperate regions, predicted to affect microbial biodiversity. Photosynthetic organisms being at the base of ecosystem’s trophic networks, we compared an endolithic desiccation-tolerant Chroococcidiopsis cyanobacteria isolated from gypsum rocks in the Atacama Desert, with a freshwater desiccation-sensitive Synechocystis. We sought whether some acclimation traits in response to desiccation and temperature variations were shared, to evaluate the potential of temperate species to possibly become resilient to future arid conditions. When temperature varies, Synechocystis tunes the acyl composition of its lipids, via a homeoviscuous acclimation mechanism known to adjust membrane fluidity, whereas no such change occurs in Chroococcidiopsis. Vice versa, a combined study of photosynthesis and pigment content shows that Chroococcidiopsis remodels its photosynthesis components and keeps an optimal photosynthetic capacity at all temperatures, whereas Synechocystis is unable to such adjustment. Upon desiccation on a gypsum surface, Synechocystis is rapidly unable to revive, whereas Chroococcidiopsis is capable to recover after three weeks. Using X-ray diffraction, we found no evidence that Chroococcidiopsis could use water extracted from gypsum crystal in such conditions, as a surrogate of missing water. The sulfolipid sulfoquinovosyldiacylglycerol becomes the prominent membrane lipid in both dehydrated cyanobacteria, highlighting an overlooked function for this lipid. Chroococcidiopsis keeps a minimal level of monogalactosyldiacylglycerol, which may be essential for the recovery process. Results support that two independent adaptation strategies have evolved in these species to cope with temperature and desiccation increase, and suggest some possible scenarios for microbial biodiversity change triggered by climate change.

    ano.nymous@ccsd.cnrs.fr.invalid (Damien Douchi) 12 Nov 2023

    https://hal.science/hal-04281075v1
  • [hal-04731720] Monogalactosyldiacylglycerol synthase isoforms play diverse roles inside and outside the diatom plastid

    Diatoms derive from a secondary endosymbiosis event, which occurred when a eukaryotic host cell engulfed a red alga. This led to the formation of a complex plastid enclosed by four membranes: two innermost membranes originating from the red alga chloroplast envelope, and two additional peri- and epiplastidial membranes (PPM, EpM). The EpM is linked to the endoplasmic reticulum (ER). The most abundant membrane lipid in diatoms is monogalactosyldiacylglycerol (MGDG), synthesized by galactosyltransferases called MGDG synthases (MGDs), conserved in photosynthetic eukaryotes and considered to be specific to chloroplast membranes. Similar to angiosperms, a multigenic family of MGDs has evolved in diatoms, but through an independent process. We characterized MGDα, MGDβ and MGDγ in Phaeodactylum tricornutum, combining molecular analyses, heterologous expression in Saccharomyces cerevisiae, and studying overexpressing and CRISPR-Cas9-edited lines. MGDα localizes mainly to thylakoids, MGDβ to the PPM, and MGDγ to the ER and EpM. MGDs have distinct specificities for diacylglycerol, consistent with their localization. Results suggest that MGDα is required for thylakoid expansion under optimal conditions, while MGDβ and MGDγ play roles in plastid and non-plastid membranes and in response to environmental stress. Functional compensation among MGDs likely contributes to diatom resilience under adverse conditions and to their ecological success.

    ano.nymous@ccsd.cnrs.fr.invalid (Nolwenn Guéguen) 03 Dec 2024

    https://hal.science/hal-04731720v2

Modification date: 08 January 2025 | Publication date: 08 November 2023 | By: B-BEST