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 37°C. From the thermogenesis curves, the thermokinetic equations were established under different conditions. The kinetics showed that a low concentration of Se (1-10 μg/mL) promoted the growth of E. coli, and a high concentration of Se (>10 μg/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 μg/ml and Cu²(+) was 1-20 μg/ml. There was a negative synergistic effect of Se and Cu²(+) on E. coli when Se was higher than 10 μg/ml and Cu²(+) was higher than 20 μg/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.