Concentration responses of toxicity sensor with Shewanella oneidensis MR-1 growing in bioelectrochemical systems

Bioelectrochemical systems (BESs) provide an opportunity to detect biological toxicity of water samples. However, the concentration responses of toxins had not been investigated in detail. Using formaldehyde as a toxic substance, the current responses were analyzed over a concentration range from 0.01% to 0.10% in a single chambered BES with 0 mV (versus saturated calomel electrode) applied on the anode. The decay percentages of currents increased in proportion with the concentration of formaldehyde after 10000 s (∼2.8 h), with the peak R2 of 0.9361 observed at 35,000 s (∼9.7 h). Fitting results of exponential decay equation showed that the magnification factor (a) closely related with baseline currents and the toxicity factor (b) was in direct proportion to formaldehyde concentration (from 0% to 0.08%) except over the high concentration of 0.10%. These results provide preliminary information about toxin concentration responses in BESs.

► Poised potential MFCs growing S. oneidensis MR-1 were constructed as toxicity sensor. ► Responses of formaldehyde concentration (Cf) from 0.01% to 0.10% were analyzed. ► The decay percentage of current was in proportion with Cf after 10,000 s. ► The toxic factor in exponential decay equation linearly related with Cf except 0.10%.