Feeding Experiments

Thirty milliliter of liquid NL19 medium was inoculated with 300 μl of a 22 h old seed culture of the strain Streptomyces sp. IB2014/011-12. After 10 h of growth on a rotary shaker at 28°C, the culture was supplemented with 200 μl of Glycine-2-¹³C or 200 μl methionine(-methyl-¹³C) respectively, solved in water (5.2 mg/ml). This procedure was repeated four times every 10–12 h. The final concentration of compounds in the flask was 2.31 mM of Glycine-2-¹³C and 1.16 mM of methionine(-methyl-¹³C). After 7 days of cultivation, the culture was extracted separately, biomass with acetone/methanol (1:1) and the supernatant with ethyl acetate. The solvent was evaporated and the obtained residues solved in MeOH. The extracts were subjected to LC-MS analysis.