Secretory Production of Tocotrienols in Saccharomyces cerevisiae

Abstract

Tocotrienols as important components of vitamin E have attracted increasing attention, with recent progress made in their heterologous biosynthesis, but all as intracellular products. Aiming to further improve the tocotrienol production capacity of engineered yeast and to advance toward industrial fermentation of tocotrienols, we first optimized the synthetic pathway to enhance the tocotrienol yield and then attempted to realize their secretory production by exploring biphasic extractive fermentation conditions and screening for endogenous transporters. Finally, a Saccharomyces cerevisiae strain with tocotrienol yield of 25.57 mg/g dry cell weight was generated, and the tocotrienol titer reached 82.68 mg/L in shake-flask cultures, with 73.66% of the product secreted into the organic phase. For the first time, we have reported that the vitamin E components could be harvested as extracellular products of microbial cell factories, which could largely simplify the downstream process and could be of significance for fermentative production of these products.

Engineering Saccharomyces cerevisiae for enhanced (–)-α-bisabolol production

“…Xu et al improved the efficiency of the extracellular transport of rubusoside by overexpressing the yeast endogenous transporter Pdr11 and transcriptional activator Msn4, thus improving the titer of rubusoside [ 26 ]. Jiao et al simultaneously overexpressed PDR11 and YOL075C , which was favorable for the transport of tocotrienol [ 40 ]. Therefore, we tried to explore some highly efficient endogenous ABC transporters.…”

“…Finally, intracellular accumulation of the product remains a problem. Two-phase fermentation may further promote product secretion [ 40 ].…”

In Silico Prediction and Mining of Exporters for Secretory Bioproduction of Terpenoids in Saccharomyces cerevisiae

“…Results also showed that constitutive overexpression of exporters reduces biomass accumulation in engineered strains. In previous studies, controlling the expression of exporters through a feedback loop or the GAL regulatory system could effectively alleviate the impact on cell growth. It inspired this study to build a quorum sensing system , or a product-responsive biosensor , to regulate the expression of the exporters in the following research to decouple it from the cell growth period and alleviate the metabolic stress and cytotoxicity caused by exporter overexpression.…”

“…ABC transporters are widely found in various organisms, including importers for nutrient uptake and exporters for exporting substances from the cytosol to the extracellular environment . Previous studies have shown that ABC exporters in S. cerevisiae are associated with the tolerance and export of heterologous products, such as artemisinic acid and tocotrienols . These results suggested that ABC exporters are likely to have the potential for terpenoid export in S. cerevisiae .…”

Prenylation: A Critical Step for Biomanufacturing of Prenylated Aromatic Natural Products

“…The secretory production of tocotrienols in S. cerevisiae was realized by exploring biphasic extractive fermentation and overexpressing endogenous transporters, with the tocotrienol titer reaching 82.68 mg/L in shake-flask cultures and a secretion ratio of 73.66%. 176 4.3.3. MCFs for Producing Vitamin K2.…”