Screening of carotenoid-producing Rhodotorula strains isolated from natural sources

Carotenoids represent large group of various natural pigments ensuring typical coloration of plants, microorganisms and several animals. It was confirmed by many studies, that consuming these biological active compounds has positive impact for human life. Therefore, they are applied in different industrial fields, such as pharmacy, cosmetic, food, and feed industry. Due to high demand for carotenoids we would like to discover new microorganisms overproducing carotenoids. We focused on yeasts of genus Rhodotorula sp. (forty isolates), that we screened according to growth and carotenoid production on Petri dishes and production media. After cultivation on Petri dishes we selected five strains (denoted as KF-4, KF-6, KF-24, KF-31, KF-104) with interesting pigment production and quick growth. The secondary screening on production media identified KF-104 as the best producer of carotenoid pigments with massive pigment accumulation (1.15 mg/g DCW) and yield (9.69 mg/L). The main carotenoid of KF-104 isolate was beta-carotene (35.4 %) with the accumulation of 408.7 mu g/g DCW and the yield of 3.4 mg/L. The rest were torularhodin, torulene and gamma-carotene (62.7-79.0 %). Production of torularhodin in the cells was low (0.1 to 1.4 mg/L) as was its accumulation in cells (31.2-121.0 mu g/g DCW). We continue the experimental analyses of these isolates in order understand differences in the content of individual pigments.