The dehydrogenase activity of Escherichia coli BB cell extracts was studied at different growth stages in the presence of different substrates and triphenyl tetrazolium chloride as an electron acceptor. It was shown that the highest degree of reduction of triphenyl tetrazolium chloride was observed during exponential growth of the bacteria when potassium isocitrate was used as a substrate. It was found that extracts of the bacteria during the exponential phase of growth on an inert glassy carbon electrode in a three-electrode liquid electrochemical cell manifested electrochemical activity in the presence of potassium citrate and methylene blue or potassium hexacyanoferrate(III) as redox mediators.

A protein extract of microbe cells is studied as a bioelectrocatalyst for glucose oxidation. The microbial protein extract prepared from Escherichia coliBB, which comprises all enzymes of...

The performance of a bioanode based on living cells Escherichia coli in the electrochemical oxidation of glucose is studied. It is shown that potassium ferricyanide can serve as the mediator in this bioelectrocatalytic system. The efficiency of this bioelectrocatalytic reaction with living cells depends on the mediator concentration. It is shown that the nature of buffer can affect the electrochemical responses of this system.

«Crude» extracts obtained via simple ultrasonic disintegration of microbial cell membrane are perspective bioelectrocatalysts. This extract contains all the necessary enzymes and cofactors required for oxidative or reductive conversion. The technology of synthesis of «crude extract» is simpler and less costly in comparison with technology of obtaining pure enzymes. Dialysis of the obtained extracts was performed with different molecular weight cut-off (3.5 kDa, 12-14 kDa, 25 kDa, 50 kDa). The obtained data show that after dialysis extracts lose their dehydrogenase and bioelectrocatalytic activity due to the loss of cofactors. However, the addition of NAD and NADP cofactors leads to a recovery of activity. The obtained data demonstrate that the concentration of the cofactor directly affects the rate of the bioelectrocatalytic reaction. Also, the obtained data indicate that the composition of the enzyme systems of the extract includes succinate dehydrogenase. Analyzing this data set can provide insight on increase of the electrocatalytic activity of a new type of bioelectrocatalyst.

The kinetics of bioelectrocatalytic oxidation of glucose by protein extracts—supersonic-destruction products of Escherichia coli BB cells—is studied in the presence of [Fe(CN)₆]^3– as the mediator system. The effect of the concentration of mediator, glucose, and protein extract is studied by electrochemical methods. The results are used in determination of effective parameters: the rate constant of glucose biooxidation, the constant of substrate-induced inhibition, and the activation energy. It is shown that the activation energy of this reaction falls into the interval of activation energies of dehydrogenase reactions. The voltammetric characteristics of a model asymmetrical biofuel cell which employs the protein extract as the anodic catalyst are determined. The maximum specific power of such model biofuel cell is found to be 400 µW/cm² (4 W/m²).

Organic-inorganic hybrid (OIH) material copper iodide-polypyrrole (CuI-PPy) obtained by the one-pot method in aqueous mixed solutions of precursors was used as a bacteriostatic and bactericidal agent in media containing Escherichia coli BB culture. Addition of OIH material at a concentration of 1 mg/mL to the culture media suppressed E. coli growth for 60 h, after which the efficiency of the bacteriostatic action was more than 80%. The use of CuI-PPy as an additive to the paint and varnish coating leads to the death of bacteria after 1 h of contact of the solution with bacterial cells with glass plates coated with CuI-PPy modified paint and varnish coatings. After 12 h of contact, the bactericidal effect of CuI-PPy modified film remains unchanged. The advantages of using OIH material compared to pure CuI are discussed.