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

2018-01-05T00:00:00Z (GMT) by Eun-Hee Lee Beelee Chua Ahjeong Son
We have demonstrated the detection of cyanobacteria in eutrophic water samples using a portable electrocoagulator and NanoGene assay. The electrocoagulator is designed to preconcentrate cyanobacteria from water samples prior to analysis via NanoGene assay. Using <i>Microcystis aeruginosa</i> laboratory culture and environmental samples (cell densities ranging from 1.7 × 10<sup>5</sup> to 4.1 × 10<sup>6</sup> and 6.5 × 10<sup>3</sup> to 6.6 × 10<sup>7</sup> cells·mL<sup>–1</sup>, 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. Preconcentration efficiencies (obtained via absorbance measurement) and dry cell weight of preconcentrated cyanobacteria were then obtained and compared. For laboratory samples at cell densities from 3.2 × 10<sup>5</sup> to 4.1 × 10<sup>6</sup> cells·mL<sup>–1</sup>, the preconcentration efficiencies of electrocoagulator appeared to be stable at ∼60%. At lower cell densities (1.7 and 2.2 × 10<sup>5</sup> cells·mL<sup>–1</sup>), the preconcentration efficiencies decreased to 33.9 ± 0.2 and 40.4 ± 5.4%, respectively. For environmental samples at cell densities of 2.7 × 10<sup>5</sup> and 6.6 × 10<sup>7</sup> cells·mL<sup>–1</sup>, the electrocoagulator maintained its preconcentration efficiency at ∼60%. On the other hand, the centrifuge’s preconcentration efficiencies decreased to nondetectable 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 (<i>mcyD</i>) gene in environmental samples. The viability of the electrocoagulator as an in situ compatible alternative to the centrifuge is also discussed.