Prolonged Deltamethrin Exposure Induces Dose-Dependent Glycerol Overproduction and Efficient Deltamethrin Removal by Saccharomyces cerevisiae

Background/Objectives: Pest management strategies rely on insecticides such as deltamethrin (DM), a commonly applied type II pyrethroid. As a natural component of food-associated microflora, Saccharomyces cerevisiae inevitably encounters DM residues in crops used for fermentation processes, including dough leavening and winemaking. However, the prolonged effect of DM exposure on yeast fermentation performance and its capacity to remove DM remained unclear. Methods: In this study, S. cerevisiae was continuously exposed to a non-lethal concentration (10 mg/L) and a low-inhibition toxic concentration (30 mg/L) of DM for 30 days. Results: Yeast exhibited high removal capacity, removing 98.05 ± 1.2% and 98.28 ± 0.4% of DM at 10 mg/L and 30 mg/L, respectively. Prolonged exposure to DM at both concentrations did not significantly affect biomass formation, glucose consumption, ethanol production, or acetic acid levels. In contrast, glycerol production increased markedly, reaching 1.1 g/L and 1.5 g/L in cultures exposed to 10 mg/L and 30 mg/L DM, respectively. Consistent with these changes, the expression levels of GPD1 and GPD2, which encode rate-limiting enzymes in glycerol biosynthesis, were upregulated in a dose-dependent manner. Conclusions: Given the fact that Saccharomyces cerevisiae is a workhorse for the biotechnological industry and has a wide range of applications, including in the food industry, elevated glycerol production in yeast under DM exposure is noteworthy in terms of yeast-based applications.