Production of L-Malic Acid by Metabolically Engineered Aspergillus nidulans Based on Efficient CRISPR–Cas9 and Cre-loxP Systems

Aspergillus nidulans has been more extensively characterized than other species considering its morphology, physiology, metabolic pathways, and genetic regulation. As it a rapid growth rate accompanied by simple nutritional requirements high tolerance to extreme cultural conditions, A. is promising microbial cell factory biosynthesize various products in industry. However, remains unclear for whether also suitable host synthesizing abundant L-malic acid. In this study, we developed convenient efficient double-gene-editing system strain TN02A7 based on the CRISPR–Cas9 Cre-loxP systems. Using gene-editing system, made acid-producing strain, ZQ07, derived from TN02A7, deleting or overexpressing five genes (encoding Pyc, pyruvate carboxylase; OahA, oxaloacetate acetylhydrolase; MdhC, malate dehydrogenase; DctA, C4-dicarboxylic acid transporter; CexA, citric transporter). The yield ZQ07 increased approximately 9.6 times higher (up 30.7 g/L titer) that of original unedited which production was originally very low. findings study not only demonstrate could be used as potential biosynthesizing organic acids, but provide highly strategy filamentous fungi.