Enhancement of carotenoid biosynthesis in <i>Phaffia rhodozyma</i> PR106 under stress conditions

Abstract

Carotenoids have good biological activity in antioxidant, anti-aging and scavenging harmful free radicals. In this study, we screened a strain that produced carotenoids, and selected a stress condition which significantly improved carotenoids content. The strain was identified as <i>Phaffia rhodozyma</i> PR106. Active oxygen generator TiO₂ was the most significant factor to the carotenoids content of the <i>P. rhodozyma</i>. The content of carotenoids was 54.45 mg/g at 500 mg/L TiO₂, which was about 1.25 times of the control and the proportion of carotenoids also changed from 1:9:16 to 1:8.5:12. Further, we determined the reactive oxygen species (ROS) in YEPD medium and <i>P. rhodozyma</i>, found that the ROS (H₂O₂, O₂^-, and HO•) was significantly increased at 500 mg/L TiO₂ in YEPD medium compared with the control, but increased in <i>P. rhodozyma</i> under 1000 mg/L TiO₂ treated. These results suggested that the increase in carotenoids was related to ROS in <i>P. rhodozyma</i>.