Akademik Veri Yönetim Sistemi
FRESENIUS ENVIRONMENTAL BULLETIN, cilt.15, sa.10, ss.1232-1237, 2006 (SCI-Expanded)
Investigations over the recent years led to the identification of various compounds with a wide range of chemical structures and antimicrobial, antifungal, antiviral and toxic properties. A total of 22 samples of cultured microalgae isoated from different freshwaters of Turkey were investigated for their antibacterial and antifungal effects on some test miroorganisms by using agar diffusion method. Oscillatoria sp. H-2 strain (isolated from Burdur Lake) was displayed to be active against all test microorganisms. Sce-nedesmus sp. S-25 strain had the strongest effect (phi 12.6 mm) on Bacillus cereus RSKK 863. Extracts of Scenedesmus sp. S-25, Scenedesmus sp. S-39 and Scenedesmus sp. S-59 showed antibacterial effect as strong as vancomycin (30 mu g) on Bacillus cereus RSKK 863. All microalgal samples showed antifungal activity against Candida albicans ATCC 10239 resembling that of flukonazol (12.5 mu g/ml), except Scenedesmus sp. S-14 and Chroococcus sp. H-4. Also, effects of Oscillatoria sp. H-2 and Scenedesmus sp. S25 on viability of B. cereus RSKK 863 at different times (4, 6, 8, 10, 12, 14 hours) were investigated by viable cell-counting. Survival of B. cereus RSKK 863 exposed to Scenedesmus sp. S25 extract decreased, when compared with the control. Extracts of Oscillatoria sp. H2 and Scenedesmus sp. S-25 strains were used in the brine shrimp assay, and the LC50 values were determined by probit analysis. The LC50 value of Oscillatoria sp. H-2 was 28.45 mg/ml, and that of Scenedesmus sp. S-25 was 24.37 mg/ml. It is shown that freshwater microalgae are still a promising source of new bioactive natural products.