Microalgae starch-based bioplastics: Screening of ten strains and plasticization of unfractionated microalgae by extrusion

• Published in: Carbohydrate polymers 2019-03, Vol.208, p.142-151
• Main Authors: Mathiot, Charlie, Ponge, Pauline, Gallard, Benjamin, Sassi, Jean-François, Delrue, Florian, Le Moigne, Nicolas
• Format: Article
• Language: English
• Subjects: Bioplastics; Chemical Sciences; Engineering Sciences; Extrusion; Materials; Microalgae; Plasticization; Polymers; Starch
• ISSN: 0144-8617; 1879-1344
• DOI: 10.1016/j.carbpol.2018.12.057

[Display omitted] •Ten microalgae strains were screened for intracellular starch production.•Microalgae was enriched in starch up to 49%w/w in a sulfur-deprived medium.•Starch concentration of 5.07 g/L was achieved in flasks after 35 days.•Direct plasticization of starch-enriched microalgal biomass was performed by twin-screw extrusion. Microalgae were considered in this work as a new resource for developing starch-based bioplastics. Ten green microalgae strains were screened at lab-scale for their ability to produce starch. A long run (800 h) two-stage accumulation strategy was designed with successive cultivation in sulfur-replete, then sulfur-depleted medium in autotrophic conditions. Starch content was assessed on cell lysate by enzymatic digestion of extracted starch into glucose. Chlamydomonas reinhardtii 11-32A strain was selected as it displayed a maximum starch-to-biomass ratio of 49%w/w, 460 h after being switched to a sulfur-deprived medium. Small-scale pilot production (30 L tubular photobioreactor) with C. reinhardtii 11-32A yielded sufficient biomass quantity to investigate its direct plasticization with glycerol in a twin-screw extruder. Microstructural characterization confirmed the ability for starch-enriched microalgae to be homogeneously plasticized, and hence the possibility to use microalgae as a new platform for the development of bioplastics.