Phycoremediation potential of microalgae species for ethidium bromide removal from aqueous media

Abstract

Ethidium Bromide (EtBr) is an organic compound used in molecular biology investigations. EtBr ability of intercalating in the DNA molecule makes it a toxic substance. The objective was to evaluate the phycoremediation potentials of Chlorella vulgaris, Desmodesmus subspicatus and Raphidocelis subcapitata tested separately and in a mixture (Mix) for EtBr removal from the aqueous medium. Experiments were conducted using an initial algae biomass of 10⁶ cell/mL, exposed to 500 µg/L of EtBr. The removal efficiency (µg EtBr L⁻¹) after 3 h in each treatment were: Mix (72.8 µg.L⁻¹) >D. subspicatus (48.4 µg.L⁻¹) >R. subcapitata (24.6 µg.L⁻¹) >C. vulgaris (19.9 µg.L⁻¹). However, when EtBr mass reduction per microalgae density is considered (ng.algae⁻¹), the efficiency ranking changes to: D. subspicatus (1.9 × 10⁻⁵ng.algae⁻¹) >C. vulgaris (1.4 × 10⁻⁵ng.algae⁻¹) >Mix (9.8 × 10⁻⁶ng.algae⁻¹) >R. subcapitata (2.8 × 10⁻⁶ng.algae⁻¹). The results suggest that initial algal population density is a determinant factor for efficient EtBr removal by microalgae species in short term treatments. In order to obtain 100% of EtBr removal, it should be necessary 10¹⁰, 10¹⁰ and 10¹¹ algae.mL⁻¹ of C. vulgaris, D. subspicatus and R. subcapitata, respectively. The results strongly suggest phycoremediation can be explored as an alternative method for EtBr removal.

Keywords:

• Algal biomass
• ethidium bromide
• laboratory effluent
• microalgae density
• phycoremediation
• tertiary effluent treatment

Acknowledgment

Rodrigo Coutinho and Priscila Cunha from laboratory LABIFI at Rio de Janeiro State University-UERJ, Kissila Rabelo and Mario José dos Santos Pereira from the Laboratory of Electron Microscopy and Confocal-UERJ, Brazil are also acknowledged for their technical assistance.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors acknowledge the financial support given by the Carlos Chagas Filho Research Support Foundation of Rio de Janeiro State - FAPERJ (E-26/202.894/2018), by the Coordination for the Improvement of Higher Education Personnel – CAPES (Finance Code 001), by the National Council for Scientific and Technological Development – CNPq (308.335/2017-1; 4358.83/2018-6; 436327/2018-0) and by the Financing Agency of Studies and Project – FINEP (Conv.01.14.0081.00).