Biomanufacturing of β-carotene by S. cerevisiae under variable gravity

Onika Lyman, Dipesh Dhakal, Yousong Ding

Department of Medicinal Chemistry, University of Florida

When considering the future of manned self-sustaining missions beyond Earth, biomanufacturing is of interest to produce useful compounds without the need for resupply. Although biomanufacturing is well-developed on Earth, microgravity's influence on cellular behavior is inconclusive and continues to be a gap in the pursuit of biomanufacturing in space. Microgravity’s influences on cellular behavior remain understudied, as no universal cellular response has been elucidated. In this work, we aimed to characterize the impacts of varied gravity on β-carotene production and growth of engineered S. cerevisiae. β-carotene is an industrially relevant antioxidant and vitamin A precursor and can be produced in yeast by introducing key biosynthetic genes. We grew the engineered yeast in terrestrial bioreactors to simulate four gravity conditions, then evaluated performance on the International Space Station to examine impacts of variable gravity on growth and production of β-carotene. Our results showed simulated reduced-gravity had an adverse effect on cell density and β-carotene production. In real microgravity, cell growth was similar to ground controls, while production of the carotenoid was decreased. Our results indicated lower production when experiencing reduced-gravity stressors in both simulated and real microgravity. Discrepancies in the impacts of simulated microgravity or real spaceflight highlight the presence of additional factors at play with current terrestrial analogs for microgravity. Our study establishes a framework for the biomanufacturing of industrially relevant compounds in space, unveiling the influence of reduced gravity on yeast growth and production of engineered compounds.