P82: Screening of carotenes producing yeasts and production of beta-carotene by Sporobolomyces roseus in submerged fermentation

Carotenes, the precursors of vitamin A, are natural pigments produced alternatively by yeasts. Fermentation process could be one of the promising ways of its production. This work describes a biotechnological production of beta-carotene by a Sporobolomyces roseus yeast strain in submerged fermentation. Yeast strains, among thirteen, were selected in terms of their growth and total carotene production. The effect of pH, yeast biomass, carbon source, nitrogen source, agitation speed, and magnesium sulphate concentration were investigated applying a statistical Fractional Factorial Design (FFD). A 2² Central Composite Rotational Design (CCRD) was applied in order to optimize the levels of most influent variables pH and glucose concentration. The fermentation process by a selected yeast strain Sporobolomyces roseus, was conducted in shake-flasks varying glucose concentration from 3.0 to 22.0g/L and pH of the medium from 3 to 6.4. The system was incubated at 140 rpm for 72 hours. A maximum production of beta-carotene (1.65 mg/L) - quantified by high performance liquid chromatography (HPLC) - along with reduced quantity of other unidentified pigments was obtained when the medium contained 17.1% glucose and its pH was the highest as compared to the medium of pH 3 and 10% glucose which resulted in a reduction in formation of beta-carotene (1.35 mg/L). However, at low levels of glucose and maximum pH, there was no considerable microbial growth. It could be concluded, that beta-carotene production by submerged fermentation, is a promising alternative under optimized levels of glucose and pH.