The Influence of Temperature and Growth Rate on the Quantitative Relationship Between Potassium, Magnesium, Phosphorus and Ribonucleic Acid of Aerobacter aerogenes Growing in a Chemostat

SUMMARY: The variations in potassium, magnesium and phosphorus contents of Aerobacter aerogenes grown in a chemostat, were measured as functions of the RNA content of the organisms. The RNA content was varied by altering temperature at a fixed dilution rate under potassium-limiting conditions, and by varying the growth rate at a fixed temperature under conditions of both magnesium- and phosphate-limitation. Changes in RNA were accompanied by corresponding changes in these other cellular components such that a molar stoichiometry close to 1:4:5:8 for magnesium, potassium, RNA (nucleotide) and phosphorus, respectively, was maintained. The only significant deviation from this ratio was observed in phosphate-limited organisms at low growth rates; these organisms possessed considerable amounts of carbohydrate. It is suggested that potassium, magnesium and phosphate are implicated in polysaccharide synthesis, thus changing the quantitative relationship between these three components and RNA previously observed. The results support the suggestion that most of the potassium in growing A. aerogenes is required to maintain the functional state of ribosomal particles.