The effect of the temperature of growth on the nucleic acid and protein content of Bact. lactis aerogenes

Abstract

The variations in the cell size and in the ribonucleic-acid (RNA), deoxyribonucleic-acid (DNA) and protein content during the growth cycle of cells of Bacterium. lactis aerogenes (Aerobacter aerogenes) fully acclimatized to temperatures of 25, 31 and 42[degree]C are described and the results are compared with those obtained previously at 37[degree]C. Some properties are, in a large measure, independent of the temperature (DNA/mass, which remains relatively constant for the major part of the cycle, and the height of the maximum in size) while others are not (the position of the maximum in cell size and both the height and the position of the maxima in RNA/mass and protein/mass). An interpretation in terms of the production of "division factor" relative to cell mass and of the factors which shift the balance of RNA to DNA as the growth rate increases is given. A correlation between growth rate and the maximum levels of RNA/mass was not observed.