Disruption or reduced expression of the orotidine-5'-decarboxylase gene pyrG increases citric acid production: a new discovery during recyclable genome editing in Aspergillus niger.

In this study, we deliver two citric acid producing isolates which are amenable to high throughput genetic manipulation due to pyrG/kusA deletion. Strikingly, we demonstrate for the first time that A. niger pyrG is a promising genetic lead for generating citric acid hyper-producing strains. Our data support the hypothesis that uridine/pyrimidine biosynthetic pathway offer future avenues for strain engineering efforts.