Comparative transcriptome analysis revealed the improved β-carotene production in <i>Sporidiobolus pararoseus</i> yellow mutant MuY9

Carotenoids are ubiquitous constituents of living organisms. These structurally diverse pigments have received considerable attention due to their biotechnological applications and potential beneficial effects on human health. In this study, we characterized an over-producing β-carotene mutant of Sporidiobolus pararoseus, obtained by ultraviolet mutagenesis, named MuY9. We compared the transcriptome between the wild-type and MuY9. A total of 348 differential expressed genes (DEGs) were found, and only one DEG crtYB is involved in carotenoid biosynthesis. The overproduction of β-carotene in MuY9 should be attributed to the up-regulation of crtYB. Functional identification of crtYB was performed using heterologous complementation in Escherichia coli. Our findings indicate that the enzymatic conversions of geranylgeranyl pyrophosphate to phytoene, as well as lycopene to β-carotene, are catalyzed by this CrtYB. Furthermore, our insights into the crtYB gene should facilitate a more detailed understanding of the carotenogenic pathway in S. pararoseus, and advance the development of the genetic engineering for the bio-production of carotenoids.