Effect of culture condition on the biosynthesis of carotenoids in Rhodotorula glutinis No. 21

Changes in the biosynthesis of carotenoids caused by altering the culture c onditions of the yeast Rhodotorula glutinis No. 21 were investigated. Cells grown on lactate showed a higher production of torularhodin, one of the fi nal products, compared with those grown on glucose, but no changes were obs erved as a result of adjusting the pH at the start of the cultivation. Thes e findings suggested that the difference in the carbon source was a factor giving rise to a change in the carotenoid biosynthesis system of R. glutini s No. 21. Increases in the contents of torulene and torularhodin were relat ed to elevation of the dissolved oxygen concentration, which was adjusted b y aeration. It was concluded that this yeast switches its system of caroten oid biosynthesis according to the extracellular conditions. The results obt ained will contribute to elucidating the role of torularhodin in this non-p hototrophic yeast which produces two carotenoids, beta-carotene and torular hodin, as the final products.