Engineering growth phenotypes of Aspergillus oryzae for L-malate production.

Improving the growth status of Aspergillus oryzae is an efficient way to enhance L-malate production. However, the growth mechanism of filamentous fungi is relatively complex, which limits A. oryzae as a cell factory to produce L-malate industrially. This study determined the relationship between growth status and L-malate production. The optimal ranges of colony diameter, percentage of vegetative mycelia, and pellet number of A. oryzae were determined to be 26-30 mm, 35-40%, and 220-240/mL, respectively. To achieve this optimum range, adaptive evolution was used to obtain the evolved strain Z07 with 132.54 g/L L-malate and a productivity of 1.1 g/L/h. Finally, a combination of transcriptome analysis and morphological characterization was used to identify the relevant pathway genes that affect the growth mechanism of A. oryzae. The strategies used in this study and the growth mechanism provide a good basis for efficient L-malate production by filamentous fungi.