EFFECTS OF PHENOLIC-COMPOUNDS ON GROWTH AND METABOLIC-ACTIVITIES OF CHLORELLA-VULGARIS AND SCENEDESMUS-BIJUGATUS ISOLATED FROM SOIL

Phenol and three nitrophenols (o-nitrophenol, m-nitrophenol, p-nitrophenol), commonly occurring pollutants in natural eco-systems, were tested for their toxic effects on soil isolates of Chlorella vulgaris and Scenedesmus bijugatus, growing under phototrophic, photoheterotrophic and heterotrophic conditions. The toxicity criteria included cell number, chlorophyll, total protein and carbohydrate content, (CO2)-C-14 uptake and in vivo nitrate reductase activity. Both C. vulgaris and S. bijugatus were sensitive to the pollutants when the cultures were grown under phototrophic or heterotrophic conditions. However, the toxicity was found reversed or alleviated upon photoheterotrophic growth of the cultures. Transmission electron microscope studies revealed various cytological abnormalities in C. vulgaris in the presence of phenolics at algistatic levels.