Evaluating the Performance of <i>Yarrowia lipolytica</i> 2.2ab in Solid-State Fermentation under Bench-Scale Conditions in a Packed-Tray Bioreactor

Solid-State Fermentation (SSF) offers a valuable process for converting agri-food by-products (AFBP) into high-value metabolites, with <i>Yarrowia lipolytica</i> 2.2ab (<i>Yl</i>2.2ab) showing significant potential under laboratory-scale controlled conditions; however, its assessment in larger-scale bioreactor scenarios is needed. This work evaluates <i>Yl</i>2.2ab’s performance in a bench-scale custom-designed packed-tray bioreactor. Key features of this bioreactor design include a short packing length, a wall-cooling system, and forced aeration, enhancing hydrodynamics and heat and mass transfer within the tray. Preliminary studies under both abiotic and biotic conditions assessed <i>Yl</i>2.2ab’s adaptability to extreme temperature variations. The results indicated effective oxygen transport but poor heat transfer within the tray bed, with <i>Yl</i>2.2ab leading to a maximum growth rate of 28.15 m_gx g_ssdb⁻¹ h⁻¹ and maximum production of proteases of 40.10 U g_ssdb⁻¹ h⁻¹, even when temperatures at the packed-tray outlet were around 49 °C. Hybrid-based modeling, incorporating Computational Fluid Dynamics (CFD) and Pseudo-Continuous Simulations (PCSs), elucidated that the forced-aeration system successfully maintained necessary oxygen levels in the bed. However, the low thermal conductivity of AFBP posed challenges for heat transfer. The bioreactor design presents promising avenues for scaling up SSF to valorize AFBP using <i>Yl</i>2.2ab’s extremophilic capabilities.