Chiang Mai Journal of Science

    Butanol is a promising alternative biofuel that offers superior performance compared to other options; however, the high cost and energy consumption associated with butanol fermentation poses major challenges. This study focuses on using Thailand’s abundant molasses for butanol production, as it is a low-cost, readily available by-product of the sugar industry and contains rich nutrients that support efficient microbial fermentation as well as investigates the performance of Clostridium beijerinckii ATCC 10132 in butanol fermentation, with different pH controlling approaches and substrates. The results indicate that C. beijerinckii ATCC 10132 has the potential of producing notable concentrations of butanol under various conditions—up to 12.0 g/L with 60 g/L glucose in tryptone-yeast extract-acetate (TYA) medium, 7.4 g/L with 40 g VS/L of a 1:1 (w/w) mixture of glucose and molasses under the pH is manually adjusted between 5.5–6.0 during fermentation condition, and 7.5 g/L with 60 g/L pretreated molasses. Maintaining pH is essential for the transition from acidogenesis to solventogenesis, which enables the conversion of acids into ABE (acetone–butanol–ethanol) solvents. In contrast, relying solely on an acetate buffer allows the pH to drop too low, it cannot be self-recovered, leading to reduced solvent production. However, the preferred carbon sources for C. beijerinckii ATCC 10132 are ranked in the following order: glucose > fructose > sucrose, indicating that the strain primarily makes use of glucose over other sugars. Glucose is efficiently transported to the cell via the pyruvate pathway, facilitating rapid energy production. In contrast, sucrose which is a disaccharide of glucose and fructose, must first be hydrolyzed into its monosaccharide components before it can be metabolized, hence, introducing an additional enzymatic step that slows its utilization. Interestingly, this study demonstrates that C. beijerinckii ATCC 10132 is an interesting candidate for butanol production and the significance of pH controlling and pretreatment of substrate for improving yields. Its high butanol tolerance, efficient solvent production, and ability to thrive on inexpensive, nutrient-rich substrates like molasses indicating a clear advantage for large-scale biofuel applications, where cost-effectiveness and process robustness are critical.