The Assimilation of Amino-acids by Bacteria

SUMMARY: The assimilation of glutamic acid by washed suspensions of Staphylococcus aureus is inhibited by 8-hydroxyquinoline (oxine). Fermentation and respiration are also inhibited but only at higher concentrations of oxine than those required for the complete inhibition of assimilation. The inhibition of assimilation by oxine can be annulled by washing the cells in water or in salts of certain divalent metals; manganese salts are more effective than those of Co, Fe or Mg. The inhibition produced by high concentrations of oxine can be decreased by metals known to form chelate complexes with oxine; the addition of an equivalent of Mn completely abolishes the inhibition.

Glutamate assimilation in Staph. aureus is impaired by a deficiency during growth of either Mn or Mg, but is not abolished unless both metals are absent. Washed suspensions of Mn- and Mg-deficient cells are activated by the addition of either Mn or Mg; Mg is more effective than Mn in activating washed cells whereas Mn is more effective than Mg in activating growing cells.

Assimilation of glutamic acid is activated by either Mn or Mg, Mn being utilized preferentially during growth. In the absence of Mn, the organisms utilize Mg and the sensitivity of assimilation to inhibition by oxine decreases.