Studies on the nongrowth metabolism of the different strains of Tetrahymena cells by isothermal microcalorimetry

The nongrowth metabolic processes of Tetrahymena strains with the different cell densities were monitored by isothermal microcalorimetry, including Tetrahymena thermophila BF1, Tetrahymena thermophila SB210, Tetrahymena pyriformis GL, the mixed cells of T. thermophila BF1 and T. thermophila SB210, and the mixed cells of T. thermophila BF1 and T. pyriformis GL. All the typical power-time curves showed a decreasing trend on the whole. It was found that total heat production (Qt) and maximum heat output (Pm) decreased significantly with the decrease of cell density. Cell density did not influence significantly the maximum heat output per cell (Pcell) of Tetrahymena cells, which was probably due to enough oxygen. The Pcell and metabolic decrease rate constant (K) values for the mixture of T. thermophila BF1 and T. pyriformis GL, and that of T. thermophila BF1 and T. thermophila SB210 were similar to the mean values of Pcell and K for the corresponding single Tetrahymena strain, respectively. It was speculated that the cell mixing did not possibly influence significantly their Pcell and K values because of no competition for nutrition, oxygen, and room, and the low conjunction percentages. © 2013 Akade´miai Kiado´, Budapest, Hungary