Identification of Potential-Generating Ions in the Nutrient Solution of Bioelectrochemical System

The work considers the effect of the nutrient solution composition on the potential difference formation in the root environment. Identification of possible potential-generating ions in bioelectrochemical systems based on electactive plant and microbial interactions was carried out. The electropotential difference in the root environment was measured when growing lettuce with a nutrient solution with a double increased content of magnesium sulfate, potassium chloride and potassium dihydortophosphate. Changes in the electrical conductivity of nutrient solutions in the process of lettuce growing and the differences in the pH and concentrations of calcium, potassium, ammonium, nitrate ions in the upper and lower electrode areas of bioelectrochemical systems are analyzed. An increase in the concentration of potassium chloride and potassium dihydortophosphate in a nutrient solution led to a decrease in both biomass and the average voltage value to 221 mV and 188 mV, respectively, relatively characteristic of the control option with a classic solution of the potential difference 213 mV. The doubling of the magnesium sulfate concentration, on the contrary, caused an increase in the potential difference to an average value of 263 mV and an increase in biomass by more than 30% relative to control. Probably, magnesium sulfate plays a potential role in the formation of electogenic reactions in the root environment.