الفهرس 
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Abstract
The work described here was undertaken to achieve the broad objectives of evaluation of carotenoids productivity of five Rhodotorula strains,studying use of some agro- industrial by-products in carotenoids production,gaining informations concerning factors influencing carotenoids production and studying the effect of storage conditions on stability of produced carotenoids.
Using basal fermentation medium, the highest value of carotenoids (2328.29μg/L) was obtained by Rhodotorula glutinis NRRL Y-842 after 96 hr. of incubation in a rotary shaking incubator at 30ºC. R. armeniaca NRRL Y-17201, R. mucilaginosa NRRL Y-844, R. bogoriensis NRRL Y-5980 and R. aurantiaca NRRL Y-1584 showed feeble carotenoids production (10.99, 10.99, 71.13 and 62.73μg/L after 96, 96, 120 and 96 hrs, respectively).
Also, using - one representative strain - namely R. glutinis NRRL Y-842, some sugars and incubation time were used to investigate carotenoids production. Some cheap agro-industrial by-products were also used to minimize the cost of carotenoids production, the highest values of carotenoids produced by R. glutinis NRRL Y-842 were recorded with using untreated sugarcane molasses (1772.19 μg/L after 120 hr.), untreated beet molasses (1571.40 μg/L after 144 hr.), treated sugarcane molasses (1002.01 μg/L after 120 hr.) and glucose syrup (1831.36 μg/L after 96 hr.). The lowest values were obtained with treated vinasse (452.90 μg/L after 120 hr.), soybean flour extract (426.80 μg/L after 48 hr.) and maize flour extract (340.79 μg/L after 48 hr.).
Also, studying the effect of using different yeast extract concentrations was to minimize the amounts of yeast extract in fermentation medium in order to minimize the cost of carotenoids production.
Studying the effect of some organic and inorganic nitrogen sources on carotenoids production by R. glutinis NRRL Y-842 in basal fermentation medium, proteose peptone and urea allowed the higher productivities of carotenoids, in untreated sugarcane molasses medium, the addition of peptone and ammonium chloride to the medium lead to the maximum carotenoids production,. in untreated beet molasses medium, yeast extract and di-ammonium hydrogen ortho-phosphate promoted the highest amount of carotenoids.
Effect of different initial pH (3.0, 4.0, 5.0, 6.0, 7.0 and 8.0) on carotenoids production were studied with basal fermentation, sugarcane molasses and beet molasses media using the most favorable organic and inorganic nitrogen source for each medium.. Also effect of incubation temperature (25, 30 and 35ºC) on carotenoids production by R. glutinis NRRL Y-842 were studied with basal fermentation, sugarcane molasses and beet molasses media using the most favorable organic and inorganic nitrogen source and favorable pH for each medium.
Effect of inoculum size (2.5, 5, 7.5 and 10%) on carotenoids production by R. glutinis NRRL Y-842 with basal fermentation, sugarcane molasses and beet molasses media using the most favorable organic and inorganic nitrogen source, favorable pH and favorable temperature for each medium.
Effect of some oils (sunflower oil, mixture of linseed oil and soybean oil (1:1) and corn oil) and tween 80 addition, as activators, on carotenoids production by R. glutinis NRRL Y-842were used with basal fermentation, sugarcane molasses and beet molasses media using the most favorable organic and inorganic nitrogen source, favorable pH, favorable temperature and favorable inoculum size for each medium.
Also, effect of storage on different temperatures and presence and absence of light for 30 days were studied on produced carotenoids dissolved in di-ethyl ether, corn oil without butylated hydroxy quinone (BHQ) and corn oil with BHQ.