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Highlights

  • No publication has investigated the microbial diversity in cave ecosystems in Africa (or Algeria)
  • Main aim of this study was the identification of microorganisms with antimicrobial potential
  • The isolates were identified by molecular tools and tested for their bioactive compounds
  • The data indicated that the majority (72.86%) of the 70 isolates were active
  • The Chaabe Cave possesses a diversity of organisms that could lead to fresh sources of antibiotics

Abstract

The discovery of new antibiotics and other bioactive microbial metabolites is a priority given the frequency of the emerging multi-drug resistant pathogenic microorganisms. Thus, scientists are searching for new antibiotics in microorganisms isolated from extreme habitats such as caves. In the present study, we aimed to perform the first analysis on culturable microorganisms in the Chaabe Cave (Algeria), and to test the antimicrobial activities of the isolates (Streptomyces spp. and Penicillium spp.). The potential for antimicrobial activity of 47 strains of actinomycetes and 23 strains of fungi were tested on Candida albicans, Staphylococcus aureus, Micrococcus luteus, Listeria monocytogenes, Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. The identification of the most active actinomycetes strains by 16S rRNA gene sequence analysis revealed that these isolates were exclusively affiliated to the genus Streptomyces. On the other hand, the fungi were determined by phylogenetic analysis based on the ITS region or on the β tubulin gene and were affiliated to the genera Readeriella, Cladosporium, Aspergillus, Penicillium, Beauveria, Alternaria, Rhizopus, and Rhizomucor. The strains showed strong inhibitory activity against pathogenic microorganisms and the diameters of the inhibition zones vary between 7.5 and 34 mm for Streptomyces strains, and between 6.5 and 19.50 mm for Penicillium strains. The data indicated that the majority (72.86%) of the 70 isolates were active against at least one of the tested microorganisms. The production of nonpolyenic antifungal substances by active Streptomyces isolates was investigated using several criteria (antibacterial activity, ergosterol inhibition, and UV-visible spectra) of active extracts. The results were promising and showed that the metabolites produced by the actinomycete strains do not have a UV-visible spectrum characteristic of a polyenic structure. The Chaabe Cave possesses a diversity of microorganisms that could lead to new antibiotics necessary in the fight against drug-resistant pathogens and warrant further study.

DOI

https://doi.org/10.5038/1827-806X.47.2.2148

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This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

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