Antimicrobial Action of Esters of p-Hydroxybenzoic Acid on Escherichia coli JE1011 and Its NS Mutants

Antimicrobial Action of Esters of p-Hydroxybenzoic Acid. I

Abstract

Antimicrobial action of esters of p-hydroxybenzoic acid (PHBAE) was tested on Escherichia coli JE1011 and its NS mutants (outer membrane mutants). JE1011 was resistant to more hydrophobic PHBAE (n-propyl, isopropyl, n-butyl and isobutyl esters), while the NS mutants were sensitive to them. On treatment with EDTA, the cells of JE1011 released protein, lipopolysaccharide and phospholipids. It was shown that the outer membrane of these cells was damaged by EDTA-treatment. The more hydrophobic PHBAE had a stronger antimicrobial action on the cells of JE1011 treated with EDTA. These results suggest that the wild-type outer membrane of gram-negative bacteria functions as a permeability barrier towards the more hydrophobic PHBAE.