title: Characterization of an evolved carotenoids hyper-producer of Saccharomyces cerevisiae through bioreactor parameter optimization and Raman spectroscopy.
abstract: An evolutionary engineering approach for enhancing heterologous carotenoids production in an engineered Saccharomyces cerevisiae strain was used previously to isolate several carotenoids hyper-producers from the evolved populations. β-Carotene production was characterized in the parental and one of the evolved carotenoids hyper-producers (SM14) using bench-top bioreactors to assess the impact of pH, aeration, and media composition on β-carotene production levels. The results show that with maintaining a low pH and increasing the carbon-to-nitrogen ratio (C:N) from 8.8 to 50 in standard YNB medium, a higher β-carotene production level at 25.52 ± 2.15 mg β-carotene g(-1) (dry cell weight) in the carotenoids hyper-producer was obtained. The increase in C:N ratio also significantly increased carotenoids production in the parental strain by 298 % [from 5.68 ± 1.24 to 22.58 ± 0.11 mg β-carotene g(-1) (dcw)]. In this study, it was shown that Raman spectroscopy is capable of monitoring β-carotene production in these cultures. Raman spectroscopy is adaptable to large-scale fermentations and can give results in near real-time. Furthermore, we found that Raman spectroscopy was also able to measure the relative lipid compositions and protein content of the parental and SM14 strains at two different C:N ratios in the bioreactor. The Raman analysis showed a higher total fatty acid content in the 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. The data suggest a positive correlation between the yield of β-carotene per biomass and total fatty acid content of the cell.
authors.affiliation: Department of Chemical Engineering, Texas A&M University, College Station, TX, USA.
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Olson
authors.affiliation: Department of Chemical Engineering, Texas A&M University, College Station, TX, USA.
authors.forename: James
authors.initials: J
authors.lastname: Johnson
authors.affiliation: Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA, USA.
authors.forename: William F
authors.initials: WF
authors.lastname: Carswell
authors.affiliation: Department of Chemical Engineering, Texas A&M University, College Station, TX, USA.|Institute for the Study of Inborn Errors of Metabolism, School of Sciences, Pontificia Universidad Javeriana, Bogotá D.C., Colombia.
authors.forename: Luis H
authors.initials: LH
authors.lastname: Reyes
authors.affiliation: Department of Biological Systems Engineering, Virginia Tech, Blacksburg, VA, USA.
authors.forename: Ryan S
authors.initials: RS
authors.lastname: Senger
authors.affiliation: Department of Chemical Engineering, Texas A&M University, College Station, TX, USA. kao.katy@tamu.edu.
authors.forename: Katy C
authors.identifier: 0000-0002-1184-276X
authors.initials: KC
authors.lastname: Kao
mesh_terms: D018533:Biomass; D019149:Bioreactors; D005285:Fermentation; D009584:Nitrogen / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D013059:Spectrum Analysis, Raman; D019207:beta Carotene / Q000096:biosynthesis*
chemical_list: D019207:beta Carotene; D009584:Nitrogen
keywords: Carotenoids; Fermentation; Isoprenoids; Raman spectroscopy; Yeast