Metabolic engineering of Saccharomyces cerevisiae for neoxanthin production.

Background: Xanthophylls, a subclass of oxygenated carotenoids, are highly valued for their wide range of applications in the food and pharmaceutical industries, particularly due to their antioxidant properties and potential health benefits. Among these, neoxanthin, a less studied xanthophyll, has demonstrated significant therapeutic potential, including antioxidant and anticancer activities. Neoxanthin is also the primary precursor for the synthesis of other valuable compounds, such as fucoxanthin and β-damascenone, which are important in the cosmetic and pharmaceutical sectors.

Results: In this study, we report the first heterologous production of neoxanthin in Saccharomyces cerevisiae through a combination of metabolic and enzyme engineering. First, a S. cerevisiae strain was engineered to produce neoxanthin by expressing genes from the β-carotene and violaxanthin biosynthesis pathways. Following this, the VDL1 gene from Phaeodactylum tricornutum, responsible for converting violaxanthin into neoxanthin, was expressed, resulting in the production of 0.18 mg/g_DCW of neoxanthin. To further enhance production, a pulse-fed galactose strategy was employed during shake-flask growth, leading to a 2.5-fold increase in neoxanthin yield. Additionally, transmembrane peptides were incorporated into the yeast cells to improve the accumulation of carotenoids, generating an increase of 3.8-fold, achieving a final production of 0.7 mg/g_DCW of neoxanthin.

Conclusions: This is the highest reported yield of neoxanthin produced by engineered microorganisms, and the strategies employed here have considerable potential for scaling up production of this carotenoid.