System metabolic tools reveal fucoxanthin metabolism in Nitzschia laevis for the improvement of fucoxanthin productivity

The production of fucoxanthin from microalgae is rapidly gaining popularity due to its exceptional productivity, lack contamination, and straightforward extraction process. However, the optimal conditions for increasing biomass concentration and/or content through manipulation light carbon sources are context specific. This study explored metabolism in Nitzschia laevis under heterotrophic mixotrophic using 13 C tracer-based metabolic flux analysis, targeted metabolomics, transcriptome analysis. Mixotrophic culture at 10 μmol m -2 s -1 improved by 27.54% but decreased 15.65% compared culture. At molecular level, exposure low results a reduction TCA cycle, leading an increased toward carotenoid fatty acid biosynthesis. accumulation high levels citrate, isocitrate, α-ketoglutaric attributed reduced activity cycle. Moreover, glyceraldehyde-3-phosphate phosphoenolpyruvate was found be more active cultivation than ones, resulting substantial fucoxanthin. higher ATP NADPH consumption provided sufficient energy Furthermore, gene expression analysis revealed that upregulated genes involved biosynthesis promoted violaxanthin especially after 12 h cultivation. To improve were applied fed-batch culture, 22.92% increase accumulation. findings this offer valuable insights into advantages employing multi-stage techniques microalgal production.