Cobalt and bacterial growth, with special reference to Proteus vulgaris

Bacterial growth inhibition by amniotic fluid. V. Phosphate-to-zinc ratio as a predictor of bacterial growth-inhibitory activity

Human amniotic fluid has been shown to contain an inorganic bacterial growth-inhibitory component, zinc. The average zinc concentration in amniotic fluid was 0.44 mug per milliliter. The phosphate concentration of amniotic fluid appears to determine the expression of zinc inhibitory activity. The average phosphate concentration was 92 mug per milliliter. For 22 fluid samples tested, a phosphate-to-zinc ratio of 100 or less predicted a bactericidal fluid. A ratio between 100 and 200 predicted a bacteriostatic fluid. A ratio of greater than 200 predicted a noninhibitory fluid. The possible clinical significance of the ratio is discussed.

Ribosome precursors accumulated by Escherichia coli during incubation with cobalt chloride

The ribonucleoprotein particles that accumulate during inhibition of Escherichia coli by CoCl(2) are ribosome precursors. The RNA that they contain can be transferred intact to completed ribosomes. The particles contain less protein than do ribosomes, but this protein appears identical with proteins from the appropriate ribosomal subunit. At least one of the particles is heterogeneous.

Inhibition of bacterial growth by metal salts. A survey of effects on the synthesis of ribonucleic acid and protein

Inhibition of the growth of Escherichia coli M.R.E. 600 by six different metal salts was accompanied by a greater decrease in the synthesis of RNA than in that of protein. The action of cobalt chloride was exceptional; inhibited cells made an excess of RNA to an extent depending on the concentration of Co(2+), the time of incubation and the concentration of Mg(2+) in the medium. Preferential synthesis of RNA in the presence of cobalt chloride was not confined to E. coli but occurred to various extents in some, but not all, of the other micro-organisms that were tested. Possible reasons for the special effect of Co(2+) are discussed.

Invasion of plant tissue by bacteria under in vitro conditions

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