Exogenous fatty acid renders the improved salt tolerance in Zygosaccharomyces rouxii by altering lipid metabolism

The yeast Zygosaccharomyces rouxii has long been used in traditional fermented food whose high quality and specific flavor are closely connected with this yeast. We previously showed that the salt tolerance of Z. rouxii could further be reinforced by the incorporation of exogenous fatty acids. While the precise mechanism is still unknown, a possible hypothesis is that exogenous fatty acids could regulate lipid metabolism, altering lipids' composition in the cell membrane. Here in this study, we try to answer this question by leveraging metabolic flux analysis and lipidomics. The results suggest that the exogenous fatty acid C12:0 with isotope 13C labeled can be absorbed by Z. rouxii cells. 134 lipids displayed abundance differentiation in lipidomics, among which most lipids were generally enhanced and the unsaturation of total lipids increased under salt stress. Combined analysis of metabolic flux and lipidome changes elucidated that Z. rouxii cells improve lipids' metabolic flux and contents to enhance overall lipid synthesis against salt stress. Our finding thus suggests that engineering the lipid metabolism of yeast with synthetic biology could be a promising strategy for building a yeast cell factory with tolerance for green biological manufacturing in food production.