A new strain of Streptomyces was isolated from an Algerian soil and was tested for its antifungal activities against two species of Aspergillus: A. carbonarius and A. niger. Based on its morphological properties this isolate was identified as Streptomyces sp. It showed a good to moderate activity against target strains of two Aspergillus species by using the streak method. The fermentation of this strain in Bennett culture medium exhibited a strong activity against A. carbonarius and least activity against A. niger since the first day of incubation, and then decreased gradually until it becomes zero in the fifth day. No activity was obtained with ISP2 medium despite of the biomass abundance registered. The extraction of the antifungal activities was carried out by using of four organic solvents with different polarities: n-hexan, dichloromethane, ethyl acetate and n-butanol. However, the efficiency of the strain was tested by dish paper diffusion method and was appeared only with ethyl acetate and n-butanol solvents, with a slight advantage to ethyl acetate extract. The diameter of inhibition obtained with ethyl acetate extract against A. carbonarius was 33 mm. The ethyl acetate extract allowed us to detect two superposed active spots with frontal ratio of 0.72 and 0.80 mm. The method used was a combination between Thin Layer Chromatography and Bioautography.

Streptomyces, Aspergillus carbonarius, A. niger, antifungal activity, phytopathogenic fungi, mycotoxigenic fungi

biology

Presentation: poster