Evaluation of the capacity of the cyanobacterium Microcystis novacekii to remove atrazine from a culture medium

Abstract

The bioaccumulation of atrazine and its toxicity were evaluated for the cyanobacterium Microcystis novacekii. Cyanobacterial cultures were grown in WC culture medium with atrazine at 50, 250 and 500 μg L⁻¹. After 96 hours of exposure, 27.2% of the atrazine had been removed from the culture supernatant. Spontaneous degradation was found to be insignificant (< 9% at 500 μg L⁻¹), indicating a high efficiency for the bioaccumulation of atrazine by M. novacekii. There were no atrazine metabolites detected in the culture medium at any of the doses studied. The acute toxicity (EC₅₀) of atrazine to the cyanobacterium was 4.2 mg L⁻¹ at 96 hours demonstrating the potential for M. novacekii to tolerate high concentrations of this herbicide in fresh water environments. The ability of M. novacekii to remove atrazine combined with its tolerance of the pesticide toxicity showed in this study makes it a potential biological resource for the restoration of contaminated surface waters. These findings support continued studies of the role of M. novacekii in the bioremediation of fresh water environments polluted by atrazine.

Keywords:

• Bioaccumulation
• bioremediation
• atrazine
• cyanobacterium

Acknowledgments

The authors are grateful to the Belo Horizonte Metropolitan Laboratory (COPASA) team for carrying out the enzyme-linked immunosorbent assays and to the ICB/UFMG Laboratory of Biotechnology and Molecular Markers for performing the polymerase chain reactions for the amplification of the mcyB gene from the M. novacekii strain. This study was supported by grants from the state of Minas Gerais fostering agency, FAPEMIG.