Exploring differential traits of lipid-producing stages of the wild type and morphologically engineered strain of Aspergillus oryzae by comparative kinetic modeling

Comparative profilings of cell growth and lipid production in the morphologically engineered strain ( Δags1 ) and the wild type (WT) of Aspergillus oryzae BCC7051 were implemented. Using various nitrogen sources, a discrimination in cell morphology between the two strains was found, of which the Δags1 culture exhibited mycelial growth as small pellets in contrast to the WT. Of them, sodium nitrate and potassium nitrate were optimal for lipid production of the WT and Δags1 strains, respectively, which the highest lipid concentrations of 7.2 and 7.9 g L −1 were obtained in the respective cultures. The mathematical models of the growth kinetics and lipid phenotypes of both fungal strains were developed, enabling to distinguish three lipid-producing stages, including low lipid-producing, lipid accumulation, and lipid turnover stages. The model validation showed good performances in all nitrogen sources tested for the WT, but only NaNO 3 and mixed yeast extract/NH 4 Cl were fitted well for the Δags1 . The difference in the period of lipid-producing stages between the WT and Δags1 indicated the metabolic alterations of A. oryzae by the defect of a gene involved in the cell wall biosynthesis, which exhibited benefits for bioprocessing practices in addition to the high productivities of biomass and lipid. These findings would further permit the manipulation in the metabolic hub of the fungal production platform for other industrial purposes. Graphic abstract