Figure 4.

Biosynthesis of fusapyrone (FPY) and deoxyfusapyrone (dFPY) is N-repressed but independent of the ambient pH in F. mangiferae. (A) Measurement of FPY and dFPY levels with HPLC-HRMS. Production of FPY by FmWT under standard laboratory culture conditions i.e., liquid ICI supplemented with 6 mM or 60 mM glutamine and 6 mM or 120 mM NaNO₃ for 7 days at 30°C. FPY and dFPY are only produced in detectable amounts by FmWT in media supplemented with 6 mM NaNO₃. Experiments were performed in triplicates. Mean values and standard deviations are shown in diagram. n.d., not detected in the supernatant. (B) Quantitative determination of FPY production levels by FmWT measured with HPLC-HRMS. FmWT was cultivated in 6 mM NaNO₃ and 6 mM glutamine for 7 days at 30°C in the dark. The pH was set prior inoculation to respective levels using 100 mM NaH₂PO₄ (pH 4) and 100 mM Na₂HPO₄ (pH 8). pH levels were controlled after 7 days using pH paper. Experiments were performed in triplicates. Mean values and standard deviations are shown in diagram.