Abstract
Recently, bioprospecting in underexplored habitats has gained enhanced focus, since new taxa of marine actinobacteria can be found, and thus possible new metabolites. Actinobacteria are in the foreground due to their versatile production of secondary metabolites that present various biological activities, such as antibacterials, antitumorals and antifungals. Chilean marine ecosystems remain largely unexplored and may represent an important source for the discovery of bioactive compounds. Various culture conditions to enrich the growth of this phylum were used and 232 bacterial strains were isolated. Comparative analysis of the 16S rRNA gene sequences led to identifying genetic affiliations of 32 genera, belonging to 20 families. This study shows a remarkable culturable diversity of actinobacteria, associated to marine environments along Chile. Furthermore, 30 streptomycete strains were studied to establish their antibacterial activities against five model strains, Staphylococcus aureus, Listeria monocytogenes, Salmonella enterica, Escherichia coli and Pseudomonas aeruginosa, demonstrating abilities to inhibit bacterial growth of Gram-positive bacteria. To gain insight into their metabolic profiles, crude extracts were submitted to liquid chromatography-high resolution mass spectrometry (LC-HRMS) analysis to assess the selection of streptomycete strains with potentials of producing novel bioactive metabolites. The combined approach allowed for the identification of three streptomycete strains to pursue further investigations. Our Chilean marine actinobacterial culture collection represents an important resource for the bioprospection of novel marine actinomycetes and its metabolites, evidencing their potential as producers of natural bioproducts.
Highlights
The 2014 World Health Organization Global Report on surveillance of antimicrobial resistance has established that bacterial resistance to commonly used drugs in infection treatments has reached alarming levels in various locations of the world
Several marine samplings were performed throughout the border coast of Chile, including continental and insular territory geographically located in Polynesia, approximately 3700 km inward of the South Pacific basin
Previous experience from our group revealed that the use of different culture media had a major influence on the isolation of actinobacteria, there were contrasting results when the same culture media were employed [24,25]
Summary
The 2014 World Health Organization Global Report on surveillance of antimicrobial resistance has established that bacterial resistance to commonly used drugs in infection treatments has reached alarming levels in various locations of the world. There is an urgent need for new bioactive compounds and, despite chemical synthetic efforts, natural products still play a predominant role in drug discovery [2,3]. Taking into account all approved drugs released from 1981 to 2014, approximately 69% of them are either natural products or derived from them [3]. Isolation and culturing of pure bacterial strains and the characterization of their secondary metabolism, remains a significant tool for drug discovery. Many of the products derived from microbial biotechnology
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