The influence of iron(II) on the growth and metabolism of Chlorella vulgaris and the process of eutophization of water

The aim of the study was to investigate the effect of iron(II) on the growth and basic metabolic processes of the single-cell alga Chlorella vulgaris (Chlorophyceae). For this purpose, algae cultures were treated with iron(II) ions at concentrations of 0.1, 0.5, 2, 5, 10, 20 and 50 mg/L and then analyzed in terms of changes in the number of cells, content of monosaccharides, proteins, chlorophyll and the activity of antioxidant enzymes: superoxide dismutase and glutathione reductase. The study showed that the biggest increase in the number of cells and concentrations of the studied biochemical parameters and antioxidant enzyme activity took place under the influence of 50 mg/L iron(II) in a situation when the medium contained also manganese(II). None of the analyzed concentrations of iron(II) resulted in a reduction in the number of cells or concentrations of the biochemical parameters. It was also found that the introduction of iron(II) to a solution containing manganese(II) did not cause co-precipitation of both metals. This study indicates that iron(II) is used by algae more effectively than iron(III). The presence of this ion in an aqueous solution enhances the development of Chlorella vulgaris, which may contribute to the deepening of the eutrophication process in waters.