Adaptive laboratory evolution induces cell wall alterations for succinic acid tolerance in Saccharomyces cerevisiae

Succinic acid (SA) is a valuable chemical with broad applications; however, its high concentrations can inhibit yeast cells, reducing fermentation efficiency. In this study, adaptive laboratory evolution was used to enhance yeast tolerance to SA, resulting in several strains capable of growing in medium with 40 g/L SA. Subsequently, whole genome sequencing of the evolved strains was conducted to identify beneficial genetic adaptations. A total of eleven gene mutations were identified across three independent evolutionary lineages, six of which are associated with cell wall functionality and contribute to SA tolerance. Specifically, the deletion of MNN4 impairs mannose side chains and significantly increases resistance to SA. Additionally, the GAS1^E267K mutation modifies the surfaces of the electrostatic molecular potential and reduces substrate interaction distances, effectively remodeling the β-1,3-glucan chains in the cell wall. These findings highlight the essential role of the cell wall in enhancing yeast tolerance to SA.