Batch and fed-batch modeling of carotenoids production by Xanthophyllomyces dendrorhous using Yucca fillifera date juice as substrate

Abstract

Two reliable mathematical models for batch and fed-batch cultures were developed to describe the microbial growth and the carotenoids production of the yeast strain 25-2 of Xanthophyllomyces dendrorhous (formerly Phaffia rhodozyma). The carbon source was date juice obtained from the Yucca fillifera. In order to determine the best batch model two different specific growth rate combinations were evaluated, one for substrate saturation with product inhibition and other for substrate and product inhibition. The best specific growth resulted in the combination for terms related to both substrate and product inhibition. The batch culture model predicts biomass and carotenoids production, as well as substrate consumption at sugar concentrations ranging from 5, 10, 20 and 40 g l −1, with mean values for the coefficient of determination of 0.9836, 0.9775, 0.9828 and 0.9651, respectively. The substrate concentration for 40 g l −1 was the weakest prediction for all the experimental data set; therefore a correction term was added to improve prediction from the mathematical model. The batch model was then extended to fed-batch culture with an inlet substrate concentration of 65 g l −1 where the mean value of 0.9868 for the coefficient of determination was obtained.