The biological effect of rare earth lanthanum nitrate on the growth of Escherichia coli B have been studied with calorimetric method. There were exceptional changes on the growth thermogenic curves for high concentration of lanthanum nitrate, for example the peak high, the total quantity of heat (Q) of cultures and the growth rate constants (k) increased evidently compared with normal E. coli B culture. When the concentration of lanthanum nitrate was 300 and 500 mg/L, Q of the cultures reached to 3.89 and 2.54 times of normal culture respectively. The livability of cells and biomass of cultures were measured with biological methods, and the results show that the growth and multiplication of cells were inhibited, and the biomass decreased at high concentration of lanthanum nitrate. These revealed that inhibiting cells discharged more quantity of heat than the normal growing cells, and this phenomenon was named as “eruption of heat”. The mechanism of eruption of heat were suggested that La^3＋ ion damages of the outer cell membrane and augment its permeability, proton electron-chemistry potential energy across cell membrane was reduced or could not even be engendered, energy could not be translated into ATP effectively in the course of oxidative phosphorylation and released with heat only, so the cells growth were inhibited finally due to scarceness of current energy ATP.

Key words: lanthanum nitrate, Escherichia coli B, calorimetriy, eruption of heat, oxidative phosphorylation