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Keywords:

  • actinomycetes;
  • algae;
  • antimicrobials;
  • LC-MS analysis;
  • polyketide

Abstract

Aims

This study was designed to investigate whether culture conditions (media, seawater concentration and pH) could lead Streptomyces sundarbansensis strain (isolated from marine brown algae Fucus sp. collected from Algerian coastline) to produce bioactive secondary metabolites. The most favourable condition for the production of anti-MRSA compound 1 [2-hydroxy-5-((6-hydroxy-4-oxo-4H-pyran-2-yl)methyl)-2-propylchroman-4-one] was determined.

Methods and Results

The profile of metabolites present in the crude extracts was carried out by HPLC analysis equipped with a diode array detector evaporative light scattering detection (DAD-ELSD) or online coupled to electrospray ionization–mass spectrometry (ESI-MS). Compound 1 was the most abundant secondary metabolite by culturing the strains on starch casein agar (SCA) medium in freshwater or 50% seawater at pH 7 or 9 using agar-state fermentation method.

Conclusions

The study has shown the efficiency of HPLC/ESI-MS technique in the analysis of polyketides produced by the strain under investigation. It was possible to establish the best culture conditions for obtaining the most bioactive compound 1, previously isolated by the same strain.

Significance and Impact of the Study

Marine algae–actinobacteria associations are a particularly promising renewable system for the production of new antibacterial metabolites. Based on the promising bioactivity of the chemically characterized compound 1, the analytical methodology here applied has resulted as an effective approach for establishing its optimized production.