Background & Aim: In this study, is done during one-year research on blue–green and green algae for antimicrobial activity in Mashhad suburb. Aqueous, ether, and methanol extracts from 44 species blue – green algae and green algae were examined for antimicrobial properties against four bacteria (tow positive gram bacteria and tow negative gram bacteria) and tow fungous.
Material & Methods: Among blue–green algae, we have known 12 geniuses, which belongs to 5 families of 3 orders, our observations shows that antimicrobial activity of this algae belongs to 2 species of Nostocaceae family, one species of Chroococaceae family, one species of Heylaceae family and one species of Scytonemataceae family. Green algae belongs to 15 geniuses of 3 families and 5 orders. Which antimicrobial activity of belong to 2 species of Scenedesmaceae family and one species of Zygnemataceae family.
Results & Discussion: The result showed that a Bacillus subtilis positive gram bacterium is inhibited by tow species of green–blue algae and one species of green algae. Negative gram bacteria Staphylococcus epidermidis inhibited by tow species of blue–green algae and one species of green algae but negative gram bacteria did not show any reaction to this alga.
Conclusion: Tow cyanobacteria species and one species of green algae inhibited growth the of Candida albicans, but did not have any effect on Candida keyfer. We can get the result that positive gram bacteria are more sensitive in comparison with negative gram bacteria.