Optimization of protoplast based DNA isolation and genome analysis in a gamma-irradiated Aspergillus niger mutant strain.

Aspergillus niger is an important industrial fungus widely used for citric acid production and a range of biotechnological applications. In this study, a protoplast-based DNA isolation protocol was optimized for a gamma-irradiated A. niger AN-L103_M1 mutant strain, followed by whole-genome sequencing and functional genome analysis. Protoplast yield was strongly influenced by enzyme concentration and the molarity of the osmotic stabilizer. The highest yield was achieved at an enzyme concentration of 50 mg/mL (2.487 ± 0.04 × 10⁸ cells/mL) and 0.8 M KCl (2.550 ± 0.06 × 10⁸ cells/mL), with both factors showing significant effects (p