A new yeast strain isolated from pin cushion flower (Scabiosa atropurpura) in our laboratory was selected from 200 yeast isolates as carotenoids producer and identified as Rhodotorula glutinis var. glutinis. The selected isolate was grown in synthetic medium to study the effect of carbon to nitrogen ratio, sources of nitrogen and carbon, mineral salts and incubation temperature on carotenoids production. The results indicated the following optimal conditions: carbon to nitrogen ratio of 5, ammonium sulphate as nitrogen source, sucrose as carbon source, presence of zinc sulphate in the medium and cultivation temperature of 25?C. The studied factors affected the dry biomass as well as the proportion of carotenoids and consequently the colour of pellets of the yeast. The yeast strain was grown under the optimal conditions to study the changes occurring in the medium and the pellets during carotenoids production for 6 days. Carotenoids production started after the first day of incubation and most of the carotenoids content in the yeast cells was produced during stationary phase. The highest cellular (861 μg?g–1) and volumetric (1.9 mg?L–1) carotenoids content were ob- tained after 5 days of growth.
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