PROGRESSIVE AGENTS FOR IMPROVEMENT OF CAROTENOGENESIS IN Rhodotorula rubra

In the present study, for improvement of the carotenoid pigments production in yeast cell of Rhodotorula rubra, the effects of the presence of mineral salts (at 0.1 mg L-1 for FeSO4, CaCl2, and MgSO4) and solvents (2% vv-1 of ethanol and methanol) were investigated using glucose as a carbon source and ammonium sulphate as a nitrogen source. The results showed that the carotenogenesis activities in the cell improved in the presence of MgSO4 where the observed improvement for carotenoid yield was twelve-times higher than FeSO4 as the other effective salt and the yield was not changed by CaCl2. Also, methanol in comparison to ethanol had three- and ten-times higher influence on the yield and rate of the carotenoids production, respectively. The interaction of the solvents with the salts were also evaluated and the results indicated the combination of the MgSO4 and methanol had the highest impact on carotenogenesis performance of the cell where the carotenoids consisted of torularhodin, torulene and β-carotene were produced (yield = 6.84 mg gcell-1 and production rate = 3.98 mg L-1 day-1) after 96 h from the beginning of the process which corresponded to the stationary phase of the cell growth. The investigation of the effects of the cultivation temperature and C/N molar ratio in the presence of both methanol and MgSO4 as progressive carotenogenesis agents indicated at 30ºC and C/N = 5, the higher carotenogenesis activity was observed by the cell.