Revealing mechanisms of high protein accumulation in Graesiella emersonii WBG-1 under heterotrophic condition

Low protein content under heterotrophic conditions limits the industrial production of proteins by microalgae. In this study, Graesiella emersonii WBG-1 efficiently synthesized and accumulated proteins (64.03%) under heterotrophic conditions, distinguishing it from other microalgae. Integrated transcriptome and proteome analyses revealed that genes and proteins associated with the photosynthetic system were significantly upregulated under heterotrophic culture compared to photoautotrophic and mixotrophic conditions. Nitrogen assimilation was enhanced while carbohydrate and fatty acid biosynthesis were restricted, carbon redirected towards amino acid and protein synthesis. Ribosome biogenesis was strengthened, and translation initiation and elongation factors were upregulated, increasing the translational activity of algal cells and promoting overall protein synthesis. Overall, these findings elucidate the mechanisms underlying efficient protein synthesis in G. emersonii WBG-1 under heterotrophic conditions, offering new insights and complementary perspectives on the regulation of protein synthesis in microalgae across different nutritional modes.