Effects of seawater on carotenoid production and lipid content of engineered saccharomyces cerevisiae

Abstract

The use of seawater in fermentation can potentially reduce the freshwater burden in the bio-based production of chemicals and fuels. We previously developed a Saccharomyces cerevisiae carotenoids hyperproducer SM14 capable of accumulating 18 mg g −1 DCW (DCW: dry cell weight) of β-carotene in rich media (YPD). In this work, the impacts of seawater on the carotenoid production of SM14 were investigated. When using nutrient-reduced media (0.1× YNB) in freshwater the β-carotene production of SM14 was 6.51 ± 0.37 mg g −1 DCW; however in synthetic seawater, the production was increased to 8.67 ± 0.62 mg g −1 DCW. We found that this improvement was partially due to the NaCl present in the synthetic seawater, since supplementation of 0.5 M NaCl in freshwater increased β-carotene production to 11.85 ± 0.77 mg g −1 DCW. The combination of synthetic seawater with higher carbon-to-nitrogen ratio (C:N = 50) further improved the β-carotene production to 10.44 ± 0.35 mg g −1 DCW. We further showed that the carotenoid production improvement in these conditions is related with lipid content and composition. These results demonstrated the benefit of using seawater to improve the production of carotenoids in S. cerevisiae, and have the potential to expand the utilization of seawater.