576 J. T. HOLDEN 
Action of inhibitors 
A variety of substances other than those suspected to interfere with the supply of 
high energy compounds (e.g. azide and DNP) and structural analogues of the amino 
acid have been observed to inhibit accumulation. GALE?8 observed inhibition of 
glutamate accumulation by 8-hydroxyquinoline at levels below those which inhibit 
glycolysis. Reactivation was observed using Mg?*+ and Mn?+ which were also effective 
in restoring activity of cells grown in media low in metallic ions. Stimulation of 
tryptophane accumulation in FE. colt by Mg?*+ has been observed’ but an effect on the 
supply of energy was not excluded. 
Although GALE observed penicillin inhibition of glutamate accumulation in S. 
ABE nT 
EFFECT OF PHYSIOLOGICAL AGE AND MEDIUM TONICITY ON SENSITIVITY 
OF GLUTAMATE ACCUMULATION TO PENICILLIN INHIBITION* 

Glutamate 

Penicillin Sucrose 
Ca We2 (units| il ) (moles/1) ee ee ) 
Late Exponential fe) oO 76.3 
100 fe) 66.6 
100 0.6 75-5 
Early Exponential oO oO 71.5 
Too fe) 28.9 
100 0.6 60.0 

* L. avabinosus was incubated at 37° for go min with L-{!4C[glutamic acid 
(cf. ref. 54) and the indicated supplements. Intracellular glutamic acid was 
calculated from the isotope found in hot water extracts of centrifuged cells. 
aureus this effect was dependent on prior growth in the presence of the antibiotic. 
In L. avabinosus more reliable interpretations of the effects of this antibiotic on the 
accumulation process have been achieved by taking advantage of physiological and 
nutritional variables®*. Viewed in the light of current information regarding the 
mechanism of action of penicillin, an adequate explanation of GALE’s findings is that 
growth with penicillin leads to the production of osmotically sensitive cells due to 
defective cell wall formation. The formation and retention of high intracellular 
glutamate pools would be impossible, if not lethal, due to the inability of such cells 
to tolerate the elevated intracellular osmotic pressures which might accompany 
accumulation. This view conflicts with Maas’ recent suggestion” that penicillin 
primarily affects the accumulation system and that the commonly recognized cell 
wall effects are secondary phenomena. Our findings using L. avabinosus at various 
physiological ages do not support this interpretation. As shown in Table II] glutamate 
accumulation by cells from late exponential cultures is inhibited only slightly by 
penicillin whereas cells from early exponential cultures are much more sensitive. The 
penicillin inhibition in this case is almost completely reversed by high concentrations 
of sucrose or KCl. Early exponential phase cells contain less wall material. They 
increase markedly their capacity for glutamate accumulation during incubation in 
buffer, at the same time depositing additional cell wall substance in the absence of 
significant DNA synthesis and cell division. Clearly the accumulation system itself is 
References p. 592/594 
