Effect of Medium pH on Rhodosporidium toruloides NCYC 921 Carotenoid and Lipid Production Evaluated by Flow Cytometry

Abstract

The effect of the culture medium pH (3.5-6.0) on the carotenoid and lipid (as fatty acids) production by the yeast Rhodosporidium toruloides NCYC 921 was studied. Flow cytometry was used to evaluate the yeast's physiological response to different culture medium pH values. The yeast biomass concentration and lipid content were maxima at pH 4.0 (5.90 g/L and 21.85 % w/w, respectively), while the maximum carotenoid content (63.37 μg/g) was obtained at pH 5.0. At the exponential phase, the yeast cell size and internal complexity were similar, at different medium pH. At the stationary phase, the yeast cell size and internal complexity decreased as the medium pH increased. At the exponential phase, the proportion of cells with polarized membranes was always high (>80 %) but at the stationary phase, the proportion of yeast cells with depolarized membranes was dominant (>65 %) and increased with the medium pH increase. The results here reported may contribute for yeast bioprocesses optimization. For the first time, multiparameter flow cytometry was used to evaluate the impact of medium pH changes on the yeast cell physiological status, specifically on the yeast membrane potential, membrane integrity, cell size and internal complexity.

A single desaturase gene from red yeast Sporidiobolus pararoseus is responsible for both four- and five-step dehydrogenation of phytoene

“…In particular, red yeasts of the genera Phaffia, Rhodotorula and Sporidibolus exhibit production of considerable amounts of carotenoids (Davoli et al, 2004;Dias et al, 2016), rendering these yeast strains potential sources for industrial pigment production (Freitas et al, 2014;Yen and Chang, 2015).…”

Genome‐scale model of Rhodotorula toruloides metabolism

“…Carotenoid production in yeast has been shown to depend on cultivation conditions (Dias, Silva, Freitas, Reis, & da Silva, ; Singh et al, ) with yields of 0.28 mg/g having been achieved in fed‐batch cultivation of R. toruloides (Dias, Sousa, Caldeira, Reis, & Lopes da Silva, ). R. toruloides produces a number of carotenoids including torularhodin, torulene, γ‐carotene, and β‐carotene.…”

Enhancement of lipid accumulation in oleaginous marine yeast; Candida sp. for biodiesel production and antimicrobial properties

“…Results in Figure3a indicated that the highest lipid content (61.5%) and dry biomass (5.2 gl -1 ) were observed at pH 5, while lipid content was gradually decreasedat pH lower or higher than 5. Dias et al (2016) reported that the Rhodosporidium toruloides NCYC 921 highest biomass and lipid content were 5.90 gl -1 and 21.85%, w/w, respectively, at pH 4.0. El-Fadaly et al (2009) considered the highest production of lipidby Cryptococcus curvatus NRRLY-1511 strain at pH 5.5.…”