Effects on cell morphology of growing Pseudomonas aeruginosa, Enterobacter cloacae and Staphylococcus aureus in subinhibitory concentrations of p-aminobenzoic acid.

Light microscopy and electron microscopy studies with Enterobacter cloacae, Pseudomonas aeruginosa and Staphylococcus aureus grown in the presence of subinhibitory concentrations of p-aminobenzoic acid indicate that p-aminobenzoic acid may have a direct or indirect effect on the cell walls. The morphological effects of p-aminobenzoic acid varied with different bacterial species. E. cloacae grown in the presence of p-aminobenzoic acid produced filaments while P. aeruginosa cells were elongated and had thicker peripheral cell walls. S. aureus had increased overall cell size and thicker transverse cell walls.