Optimization of Fermentation Parameters for Enhanced Bioethanol Production by Multistress-Tolerant Saccharomycodes ludwigii APRE2 Using Undetoxified Sugarcane Bagasse Hydrolysate

The presence of various inhibitory compounds in lignocellulosic hydrolysates presents a significant challenge for bioethanol production, requiring yeasts with exceptional multistress tolerance. This study investigated the nonconventional yeast Saccharomycodes ludwigii APRE2 as a potential solution for this industrial challenge. Initial experiments revealed a promising capability: S. ludwigii APRE2 effectively produced ethanol from undetoxified sugarcane bagasse hydrolysate at 37 °C, eliminating the need for costly detoxification pretreatments typically required in industrial processes. To optimize fermentation efficiency, a central composite design (CCD) approach was implemented. This statistical method identified precise optimal parameters: sugar concentration (143.95 g/L), diammonium phosphate (4.99 g/L), pH (4.98), yeast extract (8.94 g/L), and magnesium sulfate (2.22 g/L). The optimized conditions yielded impressive results: a maximum ethanol concentration of 38.11 g/L, productivity of 1.59 g/L·h, and yield of 0.45 g/L. These metrics position S. ludwigii APRE2 competitively among other high-performing nonconventional ethanologenic yeasts. This study establishes S. ludwigii as a viable candidate for sustainable, industrial-scale bioethanol production from lignocellulosic biomass, potentially reducing production costs through elimination of detoxification steps.