Identification, Quantification and Kinetic Study of Carotenoids and Lipids in Rhodotorula toruloides CBS 14 Cultivated on Wheat Straw Hydrolysate

Abstract

Production of carotenoids and lipids by Rhodotorula toruloides CBS 14 cultivated on wheat straw hydrolysate was investigated. An ultra-high-performance liquid chromatography (UHPLC) method for carotenoid quantification was developed and validated. Saponification effects on individual carotenoid quantification were identified, and lipid and carotenoid kinetics during cultivation were determined. The carotenoids β-carotene, γ-carotene, torularhodin, and torulene were identified; β-carotene was the major carotenoid, reaching a maximum of 1.48 mg/100 g dry weight. Recoveries of the carotenoids were between 66 and 76%, except torulene and torularhodin, which had lower recoveries due to saponification effects. Total carotenoid content in saponified and unsaponified yeast extract, respectively, determined by UHPLC or photometer, respectively, was 1.99 mg/100 g and 4.02 mg β-EQ/100 g dry weight. Growth kinetics showed a positive correlation between carotenoid content and lipid accumulation. β-carotene was the major carotenoid at all time points. At the end of the cultivation, triacylglycerols (TAGs) were the major lipid class, with 58.1 ± 3.32% of total lipids. There was also a high proportion of free fatty acids, reaching from 20.5 to 41.8% of total lipids. Oleic acid (C18:1) was the major fatty acid. The lipid yield at the end of the cultivation was 0.13 g/g of sugar consumed.

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

“…Microbial oil could bring substantial benefits to the environment with limited reliability on the climate as the fatty acid profile of some SCOs remains similar to the one from terrestrial plant oils ( Abeln & Chuck, 2021 ). Oleaginous yeasts from the Rhodotorula genus, rich in palmitic acid, could replace palm oil in animal feed and bring other advantages as they grow rapidly and are an important source of carotenoids with antioxidant properties ( Nagaraj, et al, 2022 ).…”

“…Control feed Experimental feed To obtain yeast biomass, the yeast strain R. toruloides CBS 14 (Westerdijk Fungal Biodiversity Institute, Utrecht, Netherlands) was cultivated according to Blomqvist et al (2018), Nagaraj et al (2022) methods before its incorporation into the experimental feed. R. toruloides yeast cells were retrieved from glycerol stocks at −80 °C (50% v/v) and kept on YM-agar plates at 25 °C.…”

“…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.…”

Enhanced glycerol assimilation and lipid production in Rhodotorula toruloides CBS14 upon addition of hemicellulose primarily correlates with early transcription of energy-metabolism-related genes

“…Oleaginous yeasts are known to be among the fastest lipid producers on earth [9][10][11]. Among these, Rhodotorula species, which are basidiomycetes oleaginous yeasts, can convert a variety of industrial low-value residues, such as lignocellulose hydrolysates, including hemicellulose from pulp-and-paper industry or crude glycerol, a residue from biodiesel production, into lipids and carotenoids [11][12][13][14][15][16][17]. In a recent study, we could show that lipid production rate was increased in Rhodotorula species when cultured on crude glycerol and hemicellulose hydrolysate (CGHH), compared to crude glycerol (CG) as the sole carbon source [13].…”

Enhanced glycerol assimilation and lipid production in Rhodotorula toruloides CBS14 upon addition of hemicellulose primarily correlates with early transcription of energy-metabolism related genes

“…Oleaginous yeasts are known to be the fastest lipid producers on earth. Among these, Rhodotorula species, which are basidiomycetes oleaginous yeasts, can convert a variety of industrial low-value residues, such as lignocellulose hydrolysates, including hemicellulose from pulp-and-paper industry or crude glycerol, a residue from biodiesel production, into lipids and carotenoids [9][10][11][12][13][14]. In a recent study, we could show that lipid production rate was increased in Rhodotorula species when cultured on crude glycerol and hemicellulose hydrolysate (CGHH), compared to crude glycerol (CG) as the sole carbon source [10].…”