(228aq) Characterization of an Evolved Carotenoids Hyper-Producer of Saccharomyces Cerevisiae through Bioreactor Parameter Optimization and Raman Spectroscopy
AIChE Annual Meeting
2016
2016 AIChE Annual Meeting
Food, Pharmaceutical & Bioengineering Division
Poster Session: Bioengineering
Monday, November 14, 2016 - 3:15pm to 5:45pm
We have previously developed an evolutionary engineering approach for enhancing heterologous carotenoids production in an engineered Saccharomyces cerevisiae strain, and isolated several carotenoids hyper-producers from the evolved populations. In this work, we optimized β-carotene production of the parental and one of the evolved carotenoids hyper-producers (SM14) in bench-top bioreactors. We found that maintaining a low pH and increasing the carbon-to-nitrogen ratio (C:N) from 8.8 to 50 in standard YNB medium resulted in a higher β-carotene production level at 25.52 ± 2.15 mg β-carotene g-1 [dry cell weight] in the carotenoids hyper-producer. We hypothesized that the increased carotenoids production in the evolved hyper-producer and the increase in beta-carotene production at a high C:N ratio are due to increased cellular lipid contents. In this study, we demonstrate that Raman spectroscopy is capable of monitoring β-carotene production in these bioreactor cultures. Raman spectroscopy is a powerful tool because it is adaptable to large-scale fermentations and can return results in near real-time. Raman spectroscopy was successfully used to return the relative lipid compositions and protein content of the parental and SM14 strains at two different C:N ratios in the bioreactor. The data showed a higher total lipid content in SM14 compared with the parental strain and that an increased C:N ratio resulted in significant increase in total fatty acid content of both strains, strongly supporting our hypothesis. The data suggests a positive correlation between the yield of β-carotene per biomass with total lipid content of the cell, suggesting one mechanism for the hyper-production of β-carotene in SM14 to be related with increased total lipid content.