Diverse Metabolic Profiles of a Streptomyces Strain Isolated from a Hyper-arid Environment

Abstract

The metabolic profile of Streptomyces sp. strain C34, isolated from the Chilean hyper-arid Atacama Desert soil, is dependent on the culture media used for its growth. The application of an OSMAC approach on this strain using a range of cultivation media resulted in the isolation and identification of three new compounds from the rare class of 22-membered macrolactone polyketides, named chaxalactins A-C (1-3). In addition, the known compounds deferroxamine E (4), hygromycin A (5), and 5″-dihydrohygromycin A (6) were detected. The isolated compounds were characterized by NMR spectroscopy and accurate mass spectrometric analysis. Compounds 1-3 displayed strong activity against Gram-positive but weak activity Gram-negative strains tested.

Natural product diversity of actinobacteria in the Atacama Desert

“…The OSMAC strategy is considered a simple and cheap way to induce secondary metabolite production through varying the composition of the fermentation medium or varying fermentation parameters such as shaker speed, temperature, light, etc. The application of OSMAC to the strain S. leeuwenhoekii C34 successfully led to the isolation of three new metabolites, chaxalactins A-C belonging to the rare class of 22-membered macrolactone polyketides (Rateb et al 2011b). …”

“…Compounds 10-12 exhibited moderate inhibitory activities against type 4 phosphodiesterase (PDE-4b2), while 10 also showed moderate antiproliferative effects against adenocarcinoma and breast carcinoma cells (Nachtigall et al 2011). The application of OSMAC to the strain S. leeuwenhoekii C34 T led to the isolation chaxalactins A-C (13-15) belonging to the same class of 22-membered macrolactone polyketides (Rateb et al 2011b). It is worth noting that strain C34 T was isolated from the same soil sample as strain C38 and that both belong to a well-defined 16S rRNA subclade, though the two strains differ slightly in their 16S rRNA gene sequences.…”

“…It is worth noting that strain C34 T was isolated from the same soil sample as strain C38 and that both belong to a well-defined 16S rRNA subclade, though the two strains differ slightly in their 16S rRNA gene sequences. The relative configuration of 13 was obtained by analysing its crystal structure using single-crystal X-ray diffraction, which in turn allowed for determining the relative configuration of the remaining analogues by comparing their ROESY spectra and coupling constants (Rateb et al 2011b). Compounds 13-15 showed strong to moderate antibacterial effects against Gram-positive strains.…”

“…24 was obtained in large quantities reaching 100 mg/L in nutrient-deficient media (Rateb et al 2011b). Recently, S. leeuwenhoekii strain C58 was induced to produce 24 when co-cultured with A. fumigatus MR2012, while 24 was not observed in the axenic bacterial culture.…”

“…Other natural product classes Totomycin (also known as hygromycin A, 41), an aminoglycoside antibiotic first described from Streptomyces hygroscopicus in the 1950s and known for its inhibitory effect on bacterial ribosomal peptidyl transferase (Mann et al 1953), and its congener 5′′-dihydrohygromycin A 42 were isolated and characterised from S. leeuwenhoekii strain C34 T when, in the course of applying the OSMAC approach, ISP3 medium was used for bacterial fermentation (Rateb et al 2011b).…”