Fig 1.
Molecular network constructed with LC-MS/MS data obtained from the crude extracts produced by Streptomyces sp. BRB081 in six different media during seven days of cultivation.
Clusters of molecular families are depicted twice and show the detected compounds in broth and mycelium when both parts are separately extracted and across different media. Nodes corresponding to the spectral library match are colored in pink. The structures shown are related to annotated compounds.
Fig 2.
Clusters from the molecular network of the identified octapeptides surugamides (left) and of putatively new unknown metabolites (right). a) color-code discriminates nodes occurring in extracts obtained from the different matrix (broth/mycelium); b) color-code discriminates nodes occurring in extracts obtained from the different culture medium.
Fig 3.
Extracted-ion chromatogram from LC-MS analyses of broth (red) and mycelium (blue) extracts (SCB medium– 7 days). Surugamides: 1 at 22.0 min, 871.1 Da; 2 at 22.4 min, 885.1 Da; 3 at 22.9 min, 899.1 Da; 4 at 23.5 min, 913.1 Da.
Fig 4.
Surugamides production over 1, 2, 3 and 7 days of cultivation.
Comparison of peak areas over time and culture media.
Fig 5.
Chemical barcode representing the diversity from broth and mycelium extracts of one single strain (Streptomyces sp. BRB081) cultivated in 6 different media between 1 and 7 days.
A) The detail shows compounds produced after 2 days of cultivation disappear after 7 days; B) enlargement of the fingerprint of extracts from broth after 7 days of cultivation, where each line shows vertical ticks representing ions detected in extracts obtained in each media used.
Fig 6.
PCA evaluation of all extracts obtained from cultivation of Streptomyces sp. strain BRB081.
a) Scores plot highlights samples with unique chemical composition. b) Loadings plot groups A, B and C combine the compounds responsible for the differences observed in Scores plot. The red region corresponds to surugamides analogues while the pink region comprises ions m/z 648.6, 678.7, 720.8, 734.7 and the other putatively new analogues from the cluster in Fig 2.
Table 1.
BGCs of secondary metabolites predicted for Streptomyces sp. BRB081.
Fig 7.
Cytotoxic evaluation of the crude extracts (50 μg/mL) produced by Streptomyces sp. BRB081 on HCT-116 cell lines by the MTT assay.
a) Samples activities expressed as percentage considering the positive control as 100% of inhibition. Over 75% of growth inhibition threshold was determined as the parameter for positive activity. Samples code representation: Medium_Days_Part (B–Broth; M–Mycelium). b) Clusters of identified compounds colored by the activity they displayed (active/non active). c) Comparison between observed activity and days of cultivation of the surugamides cluster.