Large Polyurethane/PEDOT: PSS Porous Electrodes for Real-Time Monitoring of Ion-Driven Communication in Filamentous Cyanobacteria

Cyanobacteria play a vital role in shaping evolution and ecological transformation throughout earth's history. Over the last decades humanity has witness an increase in frequency and magnitude of poor water quality events associated with cyanobacteria strains capable of producing Taste and Odour (T&O) metabolites and toxins making them a global concern for human health and the drinking water industry.<br/><br/>In this talk we will show that the T&O<i> producer Oscillatoria</i> sp. a debilitating cyanobacteria species for the drinking water industry demonstrate electrical excitability, which is mostly governed by diffusion of Ca²⁺ ions. The breakthrough is realized by means of an ultra-sensitive electrophysiology system based on porous polyurethane (PU) foams dip-coated with poly (3, 4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT: PSS) exploiting ultra-large-area electrodes of 199 cm², which maximizes the double-layer capacitance and concomitant detection sensitivity. The measured paracrine signal of <i>Oscillatoria </i>sp. results from the sum of all individual cell contributions and scales with electrode area, hence indicating correlation with productivity and biomass. We further suggest that when <i>Oscillatoria </i>sp. operate cooperatively, the signal appears as intra- and inter-filamentary Ca²⁺ Waves (benchmarked with fluorescence probes) which are suppressed with the specific ion channel inhibitor gadolinium chloride. Overall, the analysis and hypothesis proposed pave the way for preventative water quality management through quantitative electrogenic assessments of Ca²⁺ signalling in cyanobacteria populations.