Study of the Action of Se and Cu on the Growth Metabolism of Escherichia coli by Microcalorimetry

The biological effect of Se and Cu2+ on Escherichia coli (E. coli) growth was studied by using a 3114/3236 TAM Air Isothermal Calorimeter, ampoule method, at 37A degrees C. From the thermogenesis curves, the thermokinetic equations were established under different conditions. The kinetics showed that a low concentration of Se (1-10 mu g/mL) promoted the growth of E. coli, and a high concentration of Se (> 10 mu g/mL) inhibited the growth, but the Cu2+ was always inhibiting the growth of E. coli. Moreover, there was an antagonistic or positive synergistic effect of Se and Cu2+ on E. coli in the different culture medium when Se was 1-10 mu g/ml and Cu2+ was 1-20 mu g/ml. There was a negative synergistic effect of Se and Cu2+ on E. coli when Se was higher than 10 mu g/ml and Cu2+ was higher than 20 mu g/ml. The antagonistic or synergistic effect between Se and Cu2+ on E. coli was related to the formation of Cu-Se complexes under the different experimental conditions chosen.