The Influences of Supplemental Vegetable Oils on the Growth and β-carotene Accumulation of Oleaginous Yeast-Rhodotorula glutinis

Abstract

An oleaginous red yeast, Rhodotorula glutinis, synthesizes numerous compounds of industrial value, including those used as a source of microbial lipids for biodiesel applications. It can also be used to synthesize value-added products such as β-carotene, which are commonly used in several industries. Several vegetable oils are used in the medium as a supplemental carbon source for the enhancement of lipid and β-carotene accumulation. Among them, the supplemental of 25 g/L palm oil leads to the 71% increase of biomass as compared to that of the control batch in the agitation fermenter. The addition of palm oil not only improved the biomass yield but also enhanced the growth rate as well, where maximum growth rates of 0.32 and 0.27 g/L h were obtained with and without the addition of palm oil, respectively. The high biomass obtained will certainly lead to more total lipids and β-carotene accumulated. A comparison of an agitator bioreactor and an airlift bioreactor for biomass, total lipids, and β-carotene production was performed using palm oil as the supplemental carbon source. The shear force in the agitator bioreactor regulated the mixing of the palm oil in the medium, which increased the biomass production. The addition of palm oil slightly altered the fatty acid composition, which stearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2) were the predominant fatty acids in the microbial lipids of R. glutiniss. The results of this study suggest that an agitation bioreactor with palm oil supplementation increases biomass concentration and eventually increases β-carotene production.