Decolorization of Dyes in a Bioelectrochemical System Depending on the Immobilization of Shewanella oneidensis Mr-1 Cells on the Anode Surface and Electrical Stimulation of an External Circuit.

The effect of the polarity of the electrical stimulation of the external circuit of the bioelectrochemical systems, as well as the immobilization of Shewanella oneidensis MR-1 cells containing the DyP peroxidase gene on the rate of discoloration of dyes of different types, was found. For the crystal violet triphenylmethane dye, the maximum decolorization rate by suspended S. oneidensis MR-1 cells of 2.05 ± 0.07 μM/h was noted when connecting a 1.2 V direct polarity DC voltage source. One of the minimum rates was observed with reverse polarity of the connection. For cells immobilized on the anode, the rate was higher, reaching 2.91 ± 0.09 μM/h and did not decrease with increasing substrate concentration. The lowest values were also noted for the reverse connection of the voltage source. For the azo dye congo red, the maximum rate was found for a source with direct connection and an open circuit (0.26 ± 0.01 and 0.29 ± 0.02 μM/h, respectively); the minimum value was 0.11 ± 0.02 μM/h for a reverse connection. For crystal violet decolorization products, a significant decrease in the intensity of the main absorption peak at 590 nm band was found, with no notable hypsochromic shift. The qualitative changes in the decolorization product composition were indicated by the appearance, with a direct polarity of the ionistor connection, of a new absorption maximum in the region of 360 nm. The results may be of interest for the development of new methods of bioelectrochemical cleaning. [ABSTRACT FROM AUTHOR]