Correlation Between Penicillin Resistance and Assimilation Affinity in Staphylococcus Aureus

Abstract

GRAM-POSITIVE cocci possess the ability to assimilate certain amino-acids and to concentrate them in the free state within the internal environment^1,2. The level of free amino-acid attained within the cell is determined by the balance between the rate at which the amino-acid is assimilated from the external environment and the rate at which it is metabolized within the cell³. If the assimilation process is impaired, then the level of free amino-acid within the cell will fall as metabolism continues; conversely, if the internal metabolism is inhibited, then the level will rise to a saturation value. Studies on the assimilation and concentration of glutamic acid by Gram-positive cocci have shown that the Migration across the cell-wall requires energy which can be supplied by glycolysis¹, and that the free amino-acid in the internal environment acts as a Source of glutamic acid for protein synthesis in the growing cell⁴, and also undergoes some other form of metabolism which is inhibited by triphenylmethane dyes³. When the cells are grown in penicillin, the assimilatory processes become impaired, with the result that glutamic acid and glutamine can no longer be assimilated from the external environment, and, since the internal metabolic processes are not affected, the level of free glutamic acid within the cell falls until protein synthesis, and consequently growth, can no longer take place^5,6.