Effect of Selected Cations and B Vitamins on the Biosynthesis of Carotenoids by Rhodotorula mucilaginosa Yeast in the Media with Agro-Industrial Wastes

Abstract

In recent years, there has been an increase in the search for novel raw materials for the production of natural carotenoids. Among yeasts, Rhodotorula species have the ability to synthesize carotenoids, mainly β-carotene, torulene, and torularhodin, depending on the culture conditions. This study aimed to determine the effect of selected cations (barium, zinc, aluminum, manganese) and B vitamins (biotin, riboflavin, niacin, pantothenic acid) on the biosynthesis of carotenoids by Rhodotorula mucilaginosa MK1 and estimate the percentages of β-carotene, torulene, and torularhodin synthesized by the yeast. The cultivation was carried out in a medium containing glycerol (waste resulting from biodiesel production) as a carbon source and potato wastewater (waste resulting from potato starch production) as a nitrogen source. Carotenoid biosynthesis was stimulated by the addition of aluminum (300 mg/L) or aluminum (300 mg/L) and niacin (100 µg/L) to the medium. The number of carotenoids produced by R. mucilaginosa MK1 in the medium containing only aluminum and in the medium with aluminum and niacin was 146.7 and 180.5 µg/gd.m., respectively. This content was 101% and 147% higher compared to the content of carotenoids produced by yeast grown in the control medium (73.0 µg/gd.m.). The addition of aluminum and barium seemed to have a positive effect on the biosynthesis of torulene, and the percentage of this compound increased from 31.86% to 75.20% and 68.24%, respectively. Niacin supplementation to the medium increased the percentage of torularhodin produced by the yeast from 23.31% to 31.59–33.79%. The conducted study showed that there is a possibility of intensifying carotenoid biosynthesis by red yeast and changing the percentages of individual carotenoids fractions by adding cations or B vitamins to the medium. Further research is needed to explain the mechanism of action of niacin on the stimulation of torularhodin biosynthesis.