Changes Membrane Sterol Composition To Help Candida glabrata Tolerate Low-pH Stress.

is a promising microorganism for organic acid production. The present study aimed to investigate the role of Mediator complex subunit 3 (Med3p) in protecting under low-pH conditions. To this end, genes and were deleted, resulting in the double-deletion Δ strain. The final biomass and cell viability levels of Δ decreased by 64.5% and 35.8%, respectively, compared to the wild-type strain results at pH 2.0. In addition, lack of Med3ABp resulted in selective repression of a subset of genes in the lipid biosynthesis and metabolism pathways. Furthermore, C18:1, lanosterol, zymosterol, fecosterol, and ergosterol were 13.2%, 80.4%, 40.4%, 78.1%, and 70.4% less abundant, respectively, in the Δ strain. In contrast, the concentration of squalene increased by about 44.6-fold. As a result, membrane integrity, rigidity, and H-ATPase activity in the Δ strain were reduced by 62.7%, 13.0%, and 50.3%, respectively. In contrast, overexpression of increased the levels of C18:0, C18:1, and ergosterol by 113.2%, 5.9%, and 26.4%, respectively. Moreover, compared to the wild-type results, dry cell weight and pyruvate production increased, irrespective of pH buffering. These results suggest that regulates membrane composition, which in turn enables cells to tolerate low-pH stress. We propose that regulation of Med3ABp may provide a novel strategy for enhancing low-pH tolerance and increasing organic acid production by The objective of this study was to investigate the role of Mediator complex subunit 3 (Med3ABp) and its regulation of gene expression at low pH in We found that Med3ABp was critical for cellular survival and pyruvate production during low-pH stress. Measures of the levels of plasma membrane fatty acids and sterol composition indicated that Med3ABp could play an important role in regulating homeostasis in We propose that controlling membrane lipid composition may enhance the robustness of for the production of organic acids.