Fig. 1

Antioxidant defense metabolism to detoxify ROS in response to intracellular oxidative stress in A. niger. The function genes of the antioxidant defense metabolism in the genome of A. niger CBS513.88 were annotated from homologous genes of S. cerevisiae's antioxidant system by the method of the protein BLAST. Simplified illustration of the antioxidant defense mechanism of A. niger in response to intracellular oxidative stress which is generated from the source of ROS in the endoplasmic reticulum and mitochondria. The antioxidant defense metabolism divided into four modules: NADPH regeneration, glutaredoxin system, GSH synthesis system, and transcription factor regulation. The NADPH regeneration module principally supports the provision of NADPH in A. niger through the pentose phosphate route and NAD kinase. An11g07980 (Yap1) and An06g01690 (Skn7) activate the system (GS) and thioredoxin system (TS), which coordinate transcriptional regulation. The genes overexpressed in this present study are highlighted in bold