Rhodotorula paludigena CM33 cultivation process development for high β-carotene single cell protein production

Abstract

Rhodotorula yeast has potential in terms of biotechnology for the production of various compounds for the environmental, industrial, and medical sectors. It is well known to generate carotenoid pigments that are beneficially distinguished. This investigation aimed to optimize the growth of Rhodotorula paludigena CM33 and its production of β-carotene. Response Surface Methodology was employed to optimize temperature, ammonium sulfate, and ferric chloride concentrations in a 5L-bioreactor batch culture. The optimal conditions of 30 °C, 6.2 g/L of ammonium sulfate, and 75.0 mg/L of ferric chloride provided biomass of 17.71 g/L, a specific growth rate of 0.22 h−1, and β-carotene concentration of 40.29 mg/L. Upon scaling up the cultivation process, the 22L-bioreactor displayed similar growth patterns to those of the 5L-bioreactor. However, the 22L-bioreactor exhibited higher product yields in a shorter time period. The maximum biomass production of 18.96 ± 1.31 g/L and the maximum β-carotene production of 42.81 ± 0.61 mg/L were achieved at 28 h. This scaling-up strategy resulted in improved production efficiency. Additionally, the nutritional value of the cells was evaluated, suggesting their potential as animal feed supplements. R. paludigena CM33 demonstrated a β-carotene single-cell protein content, making it a valuable source for aquaculture and livestock feed. These findings highlight the potential of this yeast strain for large-scale production of β-carotene and single-cell protein, offering nutritional benefits for animal feed.