Enhanced carbon capture, lipid and lutein production in Chlamydomonas reinhardtii under meso-thermophilic conditions using chaperone and CRISPRi system.

[Display omitted] • Chaperone and CRISPRi were first applied in algae under thermophilic condition. • Transcriptional result depicts temperature and CRISPRi effects on algal metabolism. • PGi strain showed 2.56 g/L, 23.5 and 893 mg/L of biomass, lutein and lipid at 35°C. • Thermophilic conditions affect the biomass, lipid, and CO 2 uptake in microalgae. • PGi strain had 1.08 g-CO 2 /g-DCW of CO 2 assimilation ability in mixotrophic culture. Microalgae are widely recognized as a promising bioresource for producing renewable fuels and chemicals. Microalgal biorefinery has tremendous potential for incorporation into circular bioeconomy, including sustainability, cascading use, and waste reduction. In this study, genetic engineering was used to enhance the growth, lipid and lutein productivity of Chlamydomonas reinhardtii including strains of CC400, PY9, pCHS, and PG. Notably, CRISPRi mediated on phosphoenolpyruvate carboxylase (PEPC 1) gene to down-regulate the branch pathway from glycolysis to partitioning more carbon flux to lipid was explored under meso -thermophilic condition. The best chassis PGi, which has overexpressed chaperone GroELS and applied CRISPRi resulting in the highest biomass of 2.56 g/L and also boosted the lipids and lutein with 893 and 23.5 mg/L, respectively at 35°C. Finally, all strains with CRISPRi exhibited higher transcriptional levels of the crucial genes from photosynthesis, starch, lipid and lutein metabolism, thus reaching a CO 2 assimilation of 1.087 g-CO 2 /g-DCW in mixotrophic condition. [ABSTRACT FROM AUTHOR]