Dipotassium Phosphate Enhances Ethanol Tolerance, Production, and Cell Viability of Saccharomyces cerevisiae in Batch Fermentation

Abstract

This study evaluated ethanol production and cell viability in Saccharomyces cerevisiae cultures under different concentrations of dipotassium phosphate (K₂HPO₄). Batch fermentations were carried out in shake flasks using an orbital thermostatic incubator at 30 °C, with an initial pH of 5.80. The K₂HPO₄ concentration in the culture medium was adjusted to 1.50, 2.70, and 3.20 g L⁻¹. Cultures supplemented with 3.20 g L⁻¹ K₂HPO₄ achieved the highest biomass concentration (12.10 ± 0.30 g L⁻¹). Moreover, ethanol production reached 16% (v/v) under this condition, whereas only 9% (v/v) was obtained at 1.50 g L⁻¹. Regarding volumetric ethanol productivity, a 1.6-fold increase was estimated when the K₂HPO₄ concentration was increased from 1.50 to 3.20 g L⁻¹. Additionally, under the 3.20 g L⁻¹ condition, cell viability remained above 90%, reaching a maximum of 97%, even when ethanol concentration in the broth reached 16% (v/v). In contrast, cell viability decreased by 10% and 7% at 1.50 and 2.70 g L⁻¹, respectively, when ethanol concentrations exceeded 7% (v/v). Overall, the results demonstrated that kinetic parameters such as cell viability, volumetric productivity, and ethanol concentration were positively affected by increasing K₂HPO₄ concentration, supporting its use as a nutritional strategy in the culture medium to enhance ethanol biosynthesis. These findings are particularly relevant as they highlight the potential of K₂HPO₄ as a strategic and economical nutrient to optimize ethanolic fermentations on an industrial scale, contributing to the design of bioprocesses with improvements in metabolic efficiency and prolonged productive capacity throughout the fermentation cycles.