A non-polyenic antifungal produced by a Streptomyces yatensis strain isolated from Mellah Lake in El Kala, North-East of Algeria.

ABSTRACT

OBJECTIVE: This study aimed at describing one actinomycete strain E65 that was isolated from the water of Mellah Lake in El Kala, North-East of Algeria that produces a non-polyenic antifungal. MATERIALS AND METHODS: Actinomycetes were isolated from Mellah Lake water and screened for antimicrobial activity. Antimicrobial assays were performed on ISP2 agar. The taxonomic position of the strain E65 was determined regarding phenotypic and 16S DNA sequences features. Time course of antifungal metabolites production was evaluated against Candida albicans on ISP2, ISP1 and GYEA broth. The active antifungal compound was extracted using dichloromethane and revealed by a thin layer of chromatography, chemical reagents, UV-visible and infrared spectroscopy. RESULTS: A total of 104 actinomycetes were isolated and screened for antimicrobial activity; 21 strains were active against Staphylococcus aureus, Escherichia coli and Candida albicans. The strain E65 showed a high in vitro activity against S. aureus and C. albicans and a good antifungal activity against a clinical C. albicans strain resistant to 5-fluorocytosine. Its 16S rRNA sequence shared 99% similarity with the Streptomyces yatensis type strain within the Streptomyces violaceusniger subclade of the Streptomyces hygroscopicus clade. It produced a non-polyenic antifungal, the IR spectrum of the antifungal extract corresponded to none of the antimicrobials compounds known to be produced by actinomycete of the S. hygroscopicus clade. CONCLUSION: The wetlands of El Kala, Algeria are a potential source of bioactive actinomycete that deserves to be explored and exploited. The Streptomyces yatensis E65 strain isolated from Mellah Lake brackish water produces a remarkable antifungal compound which original non-polyenic structure warrants further characterization.