Combinatorial engineering approaches for improved lipid production in Saccharomyces cerevisiae

Triacylglycerols (TAGs) hold substantial medical, nutritional, and industrial value. However, environmental concerns demand more sustainable production alternatives. A promising approach is the fermentation of TAG-accumulating microbes. In this study, we engineered a previously developed high-lipid producing Saccharomyces cerevisiae strain to further increase lipid accumulation through a combinatorial approach. We obtained up to 327 mg∙gCDW - 1 of lipid content by deleting CKB1, encoding a subunit of casein kinase 2 (CK2) related to the regulation of lipid metabolism, in combination with the deletion of SEI1 encoding a seipin. The deletion of CKB1 combined with reduced expression of ERD1 and increased expression of YFT2, genes related to ER stability and lipid droplet production, respectively, led to 329 mg∙gCDW - 1 of lipid content. Notably, in the highest lipid producer, only ERD1 and YFT2 were targeted. This strain reached up to 350 mg∙gCDW - 1 of lipid content, a 41% increase in lipid accumulation. However, the strains with the highest lipid content also showed a reduction in growth rate and final biomass accumulation. The results in this study demonstrate that the outcomes of individual modifications depend on the genetic background, emphasizing the importance of identifying the appropriate combination of target genes to achieve the desired phenotype.