Overexpression of a predicted transketolase gene and disruption of an α-1,3-glucan synthase gene in Aspergillus oryzae DGLA3 strain enhances the yield of free dihomo-γ-linolenic acid

Free dihomo-gamma-linolenic acid (DGLA), a polyunsaturated free fatty acid (FFA), can potentially be used to produce eicosanoid pharmaceuticals, such as prostaglandin E1. Previously, we constructed an Aspergillus oryzae mutant strain, named DGLA3, which produced free DGLA at an increased yield by faaA gene disruption and cooverexpression of one elongase and two desaturase genes. In this study, we achieved a further increase. Since FFA production is increased by enhancing the pentose phosphate pathway, we overexpressed a predicted transketolase gene composing the pathway in DGLA3, which consequently increased the free DGLA yield by 1.9-fold to 403 mg/L. Additionally, we disrupted the alpha-1,3-glucan synthase gene agsB involved in cell-wall biosynthesis, which further increased it by 1.3-fold to 533 mg/L. Overall, the yield increased by 2.5-fold. Free DGLA productivity and biomass increased similarly, but residual glucose concentration decreased. Increased hyphal dispersion appeared to cause additional glucose consumption, resulting in an increase in biomass and yield. [GRAPHICS] .

Automated summary

The research team successfully increased the yield of free DGLA by disrupting genes and overexpressing them in the Aspergillus oryzae mutant strain DGLA3. They also found that enhancing the pentose phosphate pathway and disrupting the alpha-1,3-glucan synthase gene agsB can further increase the production of FFA. Overall, the yield was increased by 2.5-fold.