Non- Saccharomyces Versus Industrial Saccharomyces cerevisiae in First-Generation Ethanol Production: Stress Resilience and Fermentative Evaluation in Simulated Industrial Conditions

While Saccharomyces cerevisiae is the benchmark for industrial fuel ethanol, non- Saccharomyces yeasts offer unique stress tolerance traits whose potential in first-generation (1G) bioethanol remains poorly explored. This study evaluated the stress resilience and growth/fermentative performances of Wickerhamomyces anomalus , Meyerozyma guilliermondii , and Scheffersomyces stipitis in sugarcane musts relative to industrial S. cerevisiae strains (PE-2 and CAT-1). Microplate screening across multiple stress conditions (pH, temperature, glucose, and ethanol) revealed that W. anomalus and M. guilliermondii possessed stress tolerance profiles comparable with industrial S. cerevisiae , with M. guilliermondii displaying the highest substrate affinity for glucose. Across all strains, molasses supported significantly greater biomass accumulation (2 log cycles) than sugarcane juice. In simulated industrial fed-batch fermentations with acid treatment and cell recycling across six cycles with M. guilliermondii , washing with water only resulted in the lowest conversion efficiency (0.04 g/g), whereas acid treatment significantly enhanced yield to 0.34 g/g. Conversely, S. cerevisiae CAT-1 maintained superior performance in Cycle 6 under both water (0.49 g/g) and acid (0.46 g/g) washing treatments, exhibiting no significant difference between washing treatments and demonstrating overall higher resilience and fermentative yield than M. guilliermondii following continuous biomass reuse. Although less competitive in ethanol yield under standard 1G conditions, M. guilliermondii exhibits remarkable physiological robustness, highlighting its potential for 1G ethanol if process parameters (e.g., micro-aeration or preadaptation) are optimized. The results of this work contribute to enhancing bioprocess efficiency in bioethanol production, promoting diversification and driving the transition from petroleum-based fuels to more sustainable alternatives.