ALGICIDAL EFFECT OF EXTRACTS FROM A GREEN MACROLAGAE (CHARA VULGARIS) ON THE GROWTH OF THE POTENTIALLY TOXIC CYANOBACTERIUM (MICROCYSTIS AERUGINOSA).

The extracts of Chara vulgaris (a green macroalgae) were tested to explore its algicidal potential on Microcystis aeruginosa growth. Firstly, the anticyanobacterial effect of both macroalgae aqueous (MAA) and macroalgae etyl acetate (MEA) extracts against M. aeruginosa was assessed using both the paper disc diffusion and microdilution methods. Minimum inhibitory concentrations (MIC) and minimum algicidal concentrations (MAC) were evaluated. Secondly, the growth of M. aeruginosa in response to the MEA extracts was investigated in an experimental bioassay. To reveal the potential allelochemicals, total phenols (TPs), total flavonoids (TFs), tannins (TTs) were analyzed in both MAA and MEA extracts. The identification of the phenolic compounds in MEA extracts was performed by high-performance liquid chromatography (HPLC). The results from the bioassay demonstrated that MEA extracts inhibit the growth of M. aeruginosa in a concentration dependent way. The highest inhibition rate (IR) exceeds 83% on day (d) 4 of experimentation, and achieved (97.98%) on 7-d. HPLC analysis revealed seven phenolic compounds known as effective allelochemicals. Overall, the obtained results demonstrate that MEA extracts might be proposed as a potential allelochemicals, and it can be considered as an ecofriendly alternative algaecide to control Microcystis blooms in the eutrophic water bodies. [ABSTRACT FROM AUTHOR]