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Evidence is presented that Zn(2+) and certain other multivalent cations inhibit the uptake and oxidation of substrates by Pseudomonas aeruginosa and by other bacterial cells. Tris(hydroxymethyl)aminomethane augmented this effect. Inhibition by these multivalent cations could be prevented by incubation of cellular suspensions of P. aeruginosa in phosphate buffer. In the case of other microorganisms, incubation in the presence of ethylenediaminetetraacetate also prevented the inhibition. Inhibition by Zn(2+) of the uptake and of the oxidation of substrates could be reversed by the addition of Mg(2+). Zn(2+) was shown to inhibit noncompetitively the uptake of the three substrates studied, l-alanine, d-glucose, and citrate.

Asbell, Mary A. (University of Georgia, Athens), and R. G. Eagon. Role of multivalent cations in the organization, structure, and assembly of the cell wall of Pseudomonas aeruginosa. J. Bacteriol. 92:380-387. 1966. -Incubation of Pseudomonas aeruginosa with ethylenediaminetetraacetate induced the formation of osmotically fragile rods termed osmoplasts. These could be restored to osmotically stable forms by multivalent cations. Only those cells restored by divalent cations normally found in the cell wall were capable of multiplication. The respiration of restored cells, however, was unimpaired, irrespective of whether they were capable of multiplication. Moreover, the permeability characteristics of osmoplasts and restored cells were unimpaired. When multivalent cations were chelated from the cell wall and replaced by sodium, a weakened cell wall and an osmotically fragile cell resulted. This was apparently caused by the absence of cross-linkages in the cell wall via multivalent cations. Tris(hydroxymethyl)aminomethane buffer compounded the lethal effects of ethylenediaminetetraacetate. The lipopolysaccharide component was inferred to be the site of attack by ethylenediaminetetraacetate. A mechanism for the synthesis of the lipopolysaccharide sacculus was proposed whereby negatively charged subunits are "trapped" by forming ionic and coordinate bonds intermediated by multivalent cations.