Mathematical modeling of the batch kinetics of carotenoid production by Sporidiobolus salmonicolor CBS 2636

Abstract

This study presents a mass conservation model to predict kinetics of carotenoid production by Sporidiobolus salmonicolor CBS 2636 in a batch bioreactor. Traditional models such as Monod and Levenspiel fail to account for unconsumed substrate during carotenoid synthesis. To address this limitation, an additional differential equation was incorporated into the mass balance, capturing residual substrate and improving predictions of product formation. The equations were implemented in Maple, and model parameters were adjusted using experimental data. The proposed model accurately predicted both carotenoid production and residual substrate (glucose) levels, achieving a maximum carotenoid concentration of 3418.9 μg/L at 90 h, and a specific production of 390 μg/g of cells. Although the Levenspiel model better fit the experimental data due to product inhibition effects, neither it nor the Monod model adequately described substrate consumption. The inclusion of a residual substrate equation significantly enhanced model accuracy. The results showed high glucose concentrations after 50 h, S. salmonicolor may utilize alternative carbon sources present in the medium—such as peptone or malt extract—for carotenoid biosynthesis. Although this hypothesis is supported by the observed metabolic behavior, further studies are needed to experimentally verify the contribution of these components. This work underscores the importance of advanced mathematical modeling for optimizing bioprocess control and highlights the need for improved monitoring strategies in biotechnology.