Manganese and its regulatory role on the citrate exporter CexA - exploring the citric acid production mechanism of Aspergillus niger

Abstract

Aspergillus niger is a biotechnologically important filamentous fungus used for the industrial production of citric acid. One of the most crucial factors that affect citric acid production is the amount of manganese present in the culture broth. Observations showed that the fungus develops a certain pellet-like morphology under manganese limitation conditions and that this limitation is decisive for high citric acid accumulation by A. niger. However, the exact impact of manganese on the citric acid accumulation phenotype is clear. We show the impact of manganese ions on the citrate exporter encoding gene cexA and evaluate the citric acid production capability under wild-type and cexA overexpression conditions in the presence and absence of manganese. Further targets related to manganese and citric acid production are currently being investigated.