Strategies for Recovery, Purification and Quantification of Torularhodin Produced by Rhodotorula mucilaginosa Using Different Carbon Sources

Abstract

Torularhodin is a fungus-derived carotenoid, and the lack of downstream processing of torularhodin is still a challenge for its large-scale production. To support the industrial production of torularhodin, this work initially evaluated the efficiency of carotenoid release from Rhodotorula mucilaginosa using thermal acid treatment, saponification and ultrasound-assisted enzymatic lysis. Based on the polarity, torularhodin was then purified using methanol/acetone/hexane (2/2/1, v/v/v) solution eluting from a silica cartridge. Thermal acid treatment was considered the most appropriate method for total carotenoid release and torularhodin recovery. The highest carotenoid content was 121.3 ± 7.0 μg/g dry cell weight and 63.0 ± 6.1% of torularhodin (50.5 ± 3.0 μg/g dry cell weight in total) was recovered after purification. To fast quantify the content of torularhodin extracted from yeast, the absorption coefficient (E1cm1% = 3342) of torularhodin dissolved in chloroform was assayed. With the developed strategy for torularhodin recovery, purification and quantification, the potential of this yeast to produce torularhodin using xylose and glycerol was further evaluated. It was found that carbon sources may influence the proportion of carotenoids in this yeast, but torularhodin was still the dominant pigment. The results obtained in this study identified the feasibility of sustainable production of torularhodin from Rhodotorula mucilaginosa with high efficiency and purity.