Synechococcus And Other Bloom-Forming Cyanobacteria Exhibit Unique Redox Signatures

Cyanobacteria form dense blooms that impair water quality. Although the impact of blooms on water quality largely differs depending on the species of cyanobacteria, it is challenging to distinguish cyanobacterial species with conventional sensors due to their similar physicochemical properties. Here, we conducted cyclic voltammetry to three major bloom-forming cyanobacteria, Synechococcus sp., Microcystis aeruginosa, and Anabaena circinalis without addition of redox active compounds nor chemical modifications of the working electrode. These cyanobacteria exhibited redox peaks with distinct potentials from each other, in the range of +0.60 - +0.75 V vs SHE. Because these redox potentials hardly overlap with those of other environmental electroactive bacteria, those redox peaks may be used as indicators of the onset of a cyanobacterial bloom. Given that the photo-responsive current correlated with the cell density of Synechococcus sp., electrochemical measurement would be a promising technique for a novel cyanobacterial quantification sensor, with in-built ability to identify cyanobacterial species.