Recherche dans des sols sahariens d'actinobactéries possédant des activités antifongiques

Abstract

This study focuses on isolating actinobacteria from the Grand Sahara Desert, characterized by the abundance and diversity of bacterial genera. The aim of this research was to isolate actinobacteria exhibiting antifungal activity from desert soil. Soil samples were collected from two different areas near the Metlili oasis (Souareg, Sebkha). These bacteria were isolated on Chitine agar medium, followed by the selection of 65 isolates, out of which 58 showed satisfactory growth. Microscopic examination revealed the predominance of the Streptomyces genus, while antagonism activity tests identified 16 isolates with antifungal activity, including six isolates: B1, B4, B7, S12, S18, S14. A study of the kinetics of antifungal metabolite production

in liquid medium (ISP2) showed maximum activity on the fourth day of incubation for strain S18 (31 mm against Aspergillus fumigatus and 22 mm against Candida albicans). Similarly, strain B1 exhibited maximum production on the third day of incubation (20 mm against Candida albicans and 21 mm against Aspergillus fumigatus). The most effective solvent for extracting active metabolites produced by strain S18 in ISP2 liquid medium was dichloromethane, with an inhibition diameter of 21 mm against Candida albicans ATCC 10231.