1-aminoethylphosphonic acid, an inhibitor of bacterial cell wall synthesis.

Sir: There are numerous steps in bacterial cell wall synthesisll) but the compounds inhibiting this synthesis are limited. To this group of compounds, i. e. penicillins2), cephalosporins2), ristocetin6), vancomycin7), bacillin1^ moenomycin5), prasinomycin9), cycloserine10), O-carbamyl-D-serine10), glycine8), and damino acids3) can be added 1-aminoethylphosphonic acid (AEPA). When titrated against Proteus vulgaris, using previously described methods1^ AEPA caused the same visible structural changes in the cells as did increasing concentrations of a classical cell wall antibiotic such as penicillin. Cells grown in presence of approximately 100 //g/ml of AEPA are much elongated and enlarged in girth and at somewhat higher concentrations the elongated, enlarged cells become herniated. The hernias become larger with increasing concentration of compound until at 750jug/ml most of the cells are large spheroplasts. The lowest concentrations of antibiotics which induce cells of Proteus vulgaris to become spheroplasts are summarized in Table 1. As thedl form of AEPA was used in the experiments, the compound may be twice as effective if only one isomer is active. Two related compounds, 2-aminoethylphosphonic acid and aminomethylphosphonic acid, were inacitive.