Impact of arsenate on the growth and metabolism of cyanobacterial strains isolated from gold-mining areas

Four cyanobacterial strains isolated from arsenic (As) contaminated area in Minas Gerais, Brazil namely: Pseudanabaena spp. CCM-UFV063 and CCM-UFV065, Tolypothrix sp CCM-UFV067, and Desmonostoc sp. CCM-UFV070 were grown on BG-11 and BG-11₀ culture media respectively supplemented with di-sodium hydrogen arsenate heptahydrate (As⁵⁺) at concentrations of 0, 1, 10, 100, 1000 and 5000 mg L⁻¹. The growth was measured by means of optical density daily for seven (7) days. Contents of chlorophyll a, carbohydrates, protein, and amino acids were also evaluated. Fluorescence Spectroscopy and ICP-OES were used to quantify As in cells. The cellular growth, based on OD_750nm, was significantly lower (P < 0.05) in 5000 mg L⁻¹ As. Chlorophyll a, carbohydrates and protein contents were significantly (P < 0.05) lowest in 5000 mg L⁻¹ As. Amino Acid content of studied cyanobacteria varied and were higher in higher As concentrations except for Pseudanabaena sp. CCM-UFV065. Similarly, As cells accumulation was dependent on concentration and showed the order of 5000 mg L⁻¹ > 1000 mg L⁻¹ > 100 mg L⁻¹ > 10 mg L⁻¹ > 1 mg L⁻¹ All studied cyanobacteria showed ability to absorb As(V) especially Pseudanabaena sp. CCM-UFV065 and could all be potential isolates for bioremediation of As-contaminated waters.