FIG 2.

(A) Colony formation of A. kawachii control, ΔsC ΔlaeA, ΔsC ΔlaeA2, and ΔsC ΔlaeA3 strains. Strains were cultured at 30°C for 5 days on M medium or YPD medium containing methyl red. Agar medium was inoculated with 1 × 10⁴ conidiospores. Methyl red was added as a pH indicator; it turned red at pH values of ≤4.4. (B to D) Citric acid level in culture supernatant (B), mycelial biomass production (C), and extracellular citric acid production per mycelial weight (D) by A. kawachii strains. The control, ΔsC ΔlaeA, ΔsC ΔlaeA2, and ΔsC ΔlaeA3 strains were precultured in M medium for 36 h and then transferred to CAP medium for 48 h. Means and SDs were determined from the results of 3 independent cultivations. Asterisks indicate significant difference (*, P < 0.05; ***, P < 0.001; Student’s t test) from the results for the control strain.