RESUMEN
Valencene, a kind of sesquiterpenoid with a citrus flavor, is mainly found in Valencia orange and is commonly used in cosmetics and food additives, as well as industrial synthetic nootkatone. In this study, synthetic biology was used to create a Saccharomyces cerevisiae cell factory to produce valencene. Fistly, valencene synthase gene (CnVS) from Callitropsis nootkatensis was inserted into the chromosome of the chassis strain YTT-T5. The resulting strain VAL-01 could produce 1.1 mg·L-1 valencene. Protein fusion technique was used, different valencene synthases were compared and the copy number of key genes was adjusted, yielding valencene to 436.4 mg·L-1. Then, knocking-out the transcription factor ROX1 resulted in valencene improvement by 17.4%. Moreover, the induction system of galactose was regulated, transcription factor PDR3 and INO2 were overexpressed. The engineered strain VAL-10 could produce 2 798.6 mg·L-1 valencene by high cell density fermentation method (nearly 2 500 times higher than VAL-01). This study provides a basis for green production of valencene.
RESUMEN
As an edible eukaryotic microorganism, Saccharomyces cerevisiae has the characteristics of high safety, rapid proliferation, low cost, easy transformation, etc. It has been widely used to produce vaccines, antibodies, insulin, etc. Up to now, yeast components, such as cell wall and yeast microcapsules, have been widely used in the treatment of tumors, inflammatory virus infection, post-traumatic osteoarthritis and other diseases. Among them, the components of yeast cell membrane are relatively simple and stable, which are easy to be extracted on a large scale. Therefore, yeast cell membrane material was used to construct yeast membrane vesicle nanosystem, and its biomedical application was preliminarily explored. In this study, Saccharomyces cerevisiae membrane vesicle (SMV) was prepared by co-extrusion method, and the particle size and surface potential of SMV, drug loading and release characteristics, stability, cell safety, and in vitro therapeutic effect were investigated. The results showed that the average particle size of SMV was 185.1 nm. Curcumin and silica nanoparticles were effectively encapsulated by co-incubation and ultrasonic methods, and the characteristics of cell membrane proteins were maintained. Moreover, SMV had good stability and biocompatibility. In addition, SMV could be effectively uptaken by macrophages RAW 264.7, and curcumin loaded SMV could effectively eliminate reactive oxygen species (ROS). In conclusion, the yeast plasma membrane vesicles prepared in this study could effectively deliver curcumin drugs and encapsulate nanoparticles, and could be effectively absorbed by macrophages and effectively eliminate ROS, providing new ideas and new methods for biomedical applications of yeast membrane materials.