Investigation of the toxicity, antioxidant and antimicrobial activities of some cyanobacterial strains isolated from different habitats

Cyanobacteria are known as a source of fine chemicals, renewable fuels, and toxic compounds. The present study aimed at evaluating the toxicity and antioxidant and antimicrobial activities of four cyanobacterial strains isolated from different habitats. Due to the lack of information regarding the relationship between toxicity and biological activity of the cyanobacteria in terrestrial and aquatic ecosystems of Iran, we decided to conduct a preliminary study on the cyanobacterial strains in order to identify the potentially toxic cyanobacteria strains. In this respect, biosynthesis genes related to cyanobacterial toxins, anatoxins (anaC gene), nodularins (ndaF gene) and microcystins (mcyG gene) were amplified. In addition, antioxidant, antimicrobial and biochemical properties of cyanobacterial strains have also been evaluated. The results of the molecular analysis demonstrated that only Fischerella sp. contained the microcystins (mcyG) gene. In fact, this strain encounters numerous predators in its habitat, therefore antibacterial and antioxidant metabolites found in this strain have thought to play an important role in defense mechanisms. This case is the documentation of toxicity and promotion of biological activities of a soil cyanobacterium regarding survival in competitive ecological niches.