Shake flask optimization of β-carotene production in Rhodotorula graminis RC04

Abstract

The present investigation was focused on the effects and interactions of media components on the production of β-carotene by Rhodotorula graminis. Mannitol, potassium nitrate, yeast extract, monopotassium hydrogen phosphate and magnesium sulfate medium components were screened using Plackett Burman Design to identify critical factors. Initial pH of 5.5 of the medium was found to be optimum for β-carotene production. Results suggest that higher amounts of mannitol, yeast extract, potassium nitrate and magnesium sulfate would positively affect both biomass and β-carotene accumulation. Yeast extract was critical for both β-carotene and biomass accumulation. Central composite design was used to study the impact of interaction of mannitol and yeast extract on biomass accumulation and β-carotene production. Concentration of yeast extract was found more significant than mannitol for β-carotene production. From predicted values obtained using fitted binomial equations, it was seen that mannitol should be used in the range of 10 to 20 g/L and yeast extract in the range of 9.5 to 10 g/L to achieve a biomass of 3.8 to 4.3 g/L and a β-carotene content of 190 to 220 µg/L.

Key words: Mannitol, yeast extract, Plackett Burman Design (PBD), central composite design, response surface methodology, yeast, β-carotene.