GCMS agar samples from plates with S. coelicolor sampled every 3rd day for 27 days

The samples were analyzed in batches according to a randomized run order on GC-MS. Derivatization and GCMS analysis were performed as described previously A et al. (A et al., 2005). Non-processed MS-files from the metabolic analysis were exported from the ChromaTOF software in NetCDF format to MATLAB-R2020a (Mathworks, Natick, MA, USA), where all data pre-treatment procedures (base-line correction, chromatogram alignment, data compression and Multivariate Curve Resolution) were performed.

The extracted mass spectra were identified by comparisons of their retention index and mass spectra with libraries of retention time indices and mass spectra (Schauer et al., 2005). Mass spectra and retention index comparison was performed using NIST MS 2.2 software. Annotation of mass spectra was based on reverse and forward searches in the library.

Masses and ratio between masses indicative of a derivatized metabolite were especially notified. The mass spectrum with the highest probability indicative of a metabolite and the retention index between the sample and library for the suggested metabolite was ± 5 the deconvoluted “peak” was annotated as an identification of a metabolite.