Abstract
Single-cell protein (SCP) fermentation efficiently converts carbohydrates into high-protein food products but typically relies on purified glucose. Better understanding of SCP growth on mixed sugar substrates could allow for use of lower-cost, less processed sugars and waste-derived feedstocks. Glucose-fructose mixtures are particularly relevant, as these are the main sugars in sucrose hydrolysates and are also common in many food and beverage waste streams. In this study, the growth of Fusarium venenatum on glucose-fructose mixtures was investigated experimentally and modelled using a lagged dual-substrate Monod framework incorporating inhibition of fructose growth by glucose. Batch fermentations were conducted at a fixed total sugar concentration (15 g/L) with four different initial substrate compositions. Model parameters were estimated using both single-experiment and multi-experiment fitting strategies using differential evolution and wild bootstrap uncertainty analysis. A shared parameter set reproduced biomass growth and substrate depletion across all conditions with only a modest increase in prediction error relative to individual fits. Bootstrap analysis revealed substantial correlation among uptake and inhibition parameters, while yield coefficients were well constrained. These results demonstrate that mixed-sugar growth of F. venenatum can be described using a unified kinetic model, supporting the feasibility of transitioning from glucose-only to mixed-substrate SCP fermentation.