Figure 6.

Knockout of the gene for MCCα in Aspergillus nidulans. An Aspergillus nidulans ΔmccA strain carrying a complete deletion of the gene encoding fungal MCCα is unable to utilize leucine as the sole carbon source but grows on other branched-chain amino acids. The parental strain and three independent transformants (denoted “#1”–“#3”) deleted for the mccA gene were grown on synthetic minimal medium with ammonium chloride as the nitrogen source and with 30 mM of the indicated amino acids as the sole carbon source. Plates were incubated for 5 d at 37°C. Fungi can synthesize carbohydrates from acetyl-CoA, via the glyoxylate cycle—thereby bypassing the Krebs cycle, which leads to complete oxidation of acetyl-CoA to CO₂ and water.