Xylose Metabolism and the Effect of Oxidative Stress on Lipid and Carotenoid Production in Rhodotorula toruloides: Insights for Future Biorefinery

Abstract

The use of cell factories to convert sugars from lignocellulosic biomass into chemicals in which oleochemicals and food additives, such as carotenoids, is essential for the shift towards sustainable processes. Rhodotorula toruloides is a yeast that naturally metabolises a wide range of substrates, including lignocellulosic hydrolysates, and converts them into lipids and carotenoids. In this study, xylose, the main component of hemicellulose, was used as the sole substrate for R. toruloides, and a detailed physiology characterisation combined with absolute proteomics and genome-scale metabolic models was carried out to understand the regulation of lipid and carotenoid production. To improve these productions, oxidative stress was induced by hydrogen peroxide and light irradiation and further enhanced by adaptive laboratory evolution. Based on the online measurements of growth and CO2 excretion, three distinct growth phases were identified during batch cultivations. The intracellular flux estimations correlated well with the measured protein levels and demonstrated improved NADPH regeneration, phosphoketolase activity and reduced beta-oxidation, correlating with increasing lipid yields. Light irradiation resulted in 70% higher carotenoid and 40% higher lipid yields. The presence of hydrogen peroxide did not affect the carotenoid yield but culminated in the highest lipid yield of 0.65 g/gDCW. The adapted strain showed improved fitness and 2.3-fold higher carotenoid yield than the parental strain. This work presented a holistic view of xylose conversion into microbial oil and carotenoids by R. toruloides for further cost-effective and renewable production of these molecules.

Xylose Metabolism and the Effect of Oxidative Stress on Lipid and Carotenoid Production in Rhodotorula toruloides: Insights for Future Biorefinery

“…We thank the Proteomics Core Laboratory at University of Tartu for the proteome quantification. A preprint (Pinheiro et al, 2020) has been deposited at bioRxiv. doi: 10.1101/2020.05.28.121012.…”

Erratum: Xylose Metabolism and the Effect of Oxidative Stress on Lipid and Carotenoid Production in Rhodotorula toruloides: Insights for Future Biorefinery

“…A correction has been made to the section Acknowledgments: "We thank the Proteomics Core Laboratory at University of Tartu for the proteome quantification. A preprint (Pinheiro et al, 2020) has been deposited at bioRxiv doi: 10.1101/2020.05.28.121012".…”

Oleaginous yeast Rhodotorula toruloides biomass effect on the metabolism of Arctic char (Salvelinus alpinus)

“…The yeast R. toruloides was selected in our study for its higher content of polyunsaturated fatty acids compared to L. starkeyi strains (Brandenburg et al, 2021). In addition, R. toruloides yeast is capable of producing carotenoids including torulene, torularhodin, and β-carotene (Pinheiro et al, 2020;Nagaraj et al, 2022), potentially leading to a higher antioxidant activity when preserving the fish feed.…”