Figure 4. Biosynthetic precursors and their effects on the production of haliangicin (1).

(a) Building blocks deduced from feeding experiments (red: [1-¹³C]propionate; blue: [1,2-¹³C₂]acetate; green: [U-¹³C₃]glycerol; orange: _L-[methyl-¹³C]methionine). (b) Optimization of the production of 1 by feeding the appropriate biosynthetic precursors indicated by the same colours as in Fig. 4a. The fermentation was performed for 5 days.