The present study evaluates the antibiotic activity of 58 extracts by two extraction methods A (butanol:metanol:water) and B (metanol and water) of 9 microalgal species harvested during exponential and stationary phases. Spirulina subsalsa, Chlorella miniata, C. vulgaris., C. kessleri, Oedogonium sp., Scenedesmus dimorphus, S. obliquus, S. quadricauda and C. capsulate....