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The goal of this work is the evaluation of the analytical characteristics of the determinations performed using glucose oxidase and acetylcholinesterase based electrochemical sensors, developed applying original or optimized conventional methods of enzyme immobilization. It was found that the sensitivity of glucose determination, for example, varies from 0.048 to 3.36 mA L mol -1 cm -2 and the response time of the glucose oxidase based sensors -from 5 to 30 s, according to the method of the bioreceptor immobilization. The sensitivity of the analysis is affected from the activity of the immobilized biocomponent, from the composition of the solution (concentration of the substrate, of the mediator and of the inhibitor), and from the experimental conditions (pH, temperature, agitation), as well as from the kinetic parameters of the studied process. It was found that the immobilized glucose oxidase conserves its substrate specificity in the presence of a number of glucides (galactose, maltose, fructose, and saccharose) in 100 fold higher concentrations. The selectivity of glucose analysis is ensured applying a suitable potential. Interferences free glucose amperometric determination was performed at 0.00 V/SCE, in the presence of ascorbates and urates. The electrochemical quantification of enzyme inhibitors allows reaching particularly low limits of detection (10 -9 -10 -14 mol L -1 ).

This study reports the characterization of the Tetrasphaera duodecadis bacteria and the techniques used therein. In order to evaluate the morphological characteristics of the T. duodecadis bacteria scanning electron microscope (SEM) was used throughout its different growth stages. These microorganisms were grown in vitamin B12 broths with 1% tryptone, 0.2% yeast extract, and 0.1% glucose. The turbidimetric method was employed for the determination of bacterial concentration and growth curve. The SEM results show small agglomerates of 0.8 ± 0.05 µm during the lag phase, and rod-like shapes during the exponential phase with similar shapes in the stationary phase.

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