CHLORELLA VULGARIS, A PROMISING FEEDSTOCK FOR STARCH-BASED BIOPLASTICS
Creators: name: Compadre, A.
name: Six, A.
name: Dubreuil, C.
name: Dimitriades-Lemaire, A.
name: Delrue, F.
name: Alvarez, P.
name: Fleury, G.
name: Mailley, S.
name: Sassi, J.-F.
Publisher: name: Zenodo
Year: 2021
Subjects: algae biorefineries
biomass production processes
starch
bioplastics

description: SEALIVE [1] and Nenu2PHAr [2] European projects are both engaged in the development of new sustainable value chains, supporting the development of greener and cost-effective plastics. On the one hand, starch is well known for being used as a natural biopolymer base to integrate plastics blends [3], while on the other hand, it can be degraded into monomeric glucose to feed PHA producing bacteria [4]. <em>Chlorella vulgaris</em>, a robust microalga, recognized as a remarkable starch producer [5], is already widely cultivated at industrial scale [6]. Thus, in SEALIVE and Nenu2PHAr projects, different <em>C. vulgaris</em> biorefinery schemes are proposed, focusing respectively on the production of three fractions (starch, pigments and antioxidant molecules) or on the production of a fraction suitable to feed PHA producing bacteria. To optimize volumetric starch productivity, and thus decrease the production costs of the algal-starch, two culture schemes were developed. Firstly, the “2-reactor-strategy”, where high biomass productivity is obtained in a first photobioreactor (PBR), while starch accumulation is quickly triggered in a second PBR, where culture is subject to nitrogen-deprived medium and high light intensities; and secondly, the “1-reactor strategy” where biomass production up to high-densities occurs in the same PBR in which starvation is induced. Total carbohydrate content raised up to a range of 50-70 %DW for both strategies, confirming that, nutrient-deprivation plays a crucial role on starch accumulation. Results were validated at pilot scale (25L PBRs under artificial light) and semi-industrial scale (180L PBRs under natural light). Whereas production process under natural light is being optimized, different starch purification schemes are under development, in order to effectively include <em>C. vulgaris</em> feedstock into the production of biodegradable bio-based plastics. References: [1] SEALIVE Project, https://sealive.eu/ This project has received funding from the European Union’s Horizon 2020 Research and Innovation programme under grant agreement n° 862910. [2] Nenu2PHAr project, https://nenu2phar.eu/ This project has received funding from the Bio Based Industries Joint Undertaking (BBI-JU) under grant agreement n° 887474. The BBI-JU receives support from the European Union’s Horizon 2020 research and innovation programme and the Bio Based Industries Consortium. [3] Jiang T., et al. (2020) <em>Starch-based biodegradable materials: Challenges and opportunities</em>, Advanced Industrial and Engineering Polymer Research, 3:8-18, https://doi.org/10.1016/j.aiepr.2019.11.003. [4] Jiang, G., et al. (2016<em>) Carbon Sources for Polyhydroxyalkanoates and an</em> <em>Integrated Biorefinery</em>, International Journal of Molecular Sciences, 17(7), 1157. https://doi.org/10.3390/ijms17071157 [5] Brányiková, I., et al. (2011), <em>Microalgae—</em><em>novel highly efficient starch producers</em>, Biotechnol. Bioeng., 108: 766-776. doi:10.1002/bit.23016 [6] Safi C. et al. (2014), <em>Morphology, composition, production, processing and applications of Chlorella vulgaris: A review</em>, Renewable and Sustainable Energy Reviews, 35:265-278. https://doi.org/10.1016/j.rser.2014.04.007