Detection of Cyanobacteria in Eutrophic Water Using a Portable Electrocoagulator and NanoGene Assay

Abstract

We have demonstrated the detection of cyanobacteria in eutrophic water samples using a portable electrocoagulator and NanoGene assay. The electrocoagulator is designed to pre-concentrate cyanobacteria from water samples prior to analysis via NanoGene assay. Using Microcystis aeruginosa laboratory culture and environmental samples (cell densities ranging from 1.7 X 10(5) to 4.1 X 10(6) and 6.5 X 10(3) to 6.6 X 10(7) cells.mL(-1), respectively), the electrocoagulator was evaluated and compared with a conventional centrifuge. Varying the operation duration from 0 to 300 s with different cell densities was first investigated. Pre-concentration efficiencies (obtained via absorbance measurement) and dry cell weight of pre-concentrated cyanobacteria were then obtained and compared. For laboratory samples at cell densities from 3.2 X 10(5) to 4.1 X 10(6) cells.mL(-1), the pre-concentration efficiencies of electrocoagulator appeared to be stable at similar to 60%. At lower cell densities (1.7 and 2.2 X 10(5) cells.mL(-1)), the pre-concentration efficiencies decreased to 33.9 +/- 0.2 and 40.4 +/- 5.4%, respectively. For environmental samples at cell densities of 2.7 X 105 and 6.6 X 10(7) cells.mL(-1), the electrocoagulator maintained its pre-concentration efficiency at similar to 60%. On the other hand, the centrifuges pre-concentration efficiencies decreased to non-detectable and below 40%, respectively. This shows that the electrocoagulator outperformed the centrifuge when using eutrophic water samples. Finally, the compatibility of the electrocoagulator with the NanoGene assay was verified via the successful detection of the microcystin synthetase D (mcyD) gene in environmental samples. The viability of the electrocoagulator as an in situ compatible alternative to the centrifuge is also discussed.