Outer membrane permeability of Acinetobacter calcoaceticus mediates susceptibility to rat polymorphonuclear leukocyte...

Growth of Acinetobacter calcoaceticus on specific alkanes altered the outer membrane permeability of the organism, as indicated by a change in sensitivity to the antibiotic actinomycin D. As the carbon length of the alkane energy source decreased, outer membrane permeability and susceptibility to actinomycin D increased. Concomitant with the increase in outer membrane permeability, A. calcoaceticus became more susceptible to the oxygen-independent antimicrobial activity of extracted contents from rat polymorphonuclear leukocyte granules. Individual fractions of granule extract possessed no antimicrobial activity against A. calcoaceticus. The alkane-induced change in outer membrane permeability was not associated with alterations of lipopolysaccharide O antigen. An outer membrane permeability mechanism, independent of changes in lipopolysaccharide content, mediating susceptibility to the oxygen-independent antimicrobial activity of rat polymorphonuclear leukocyte granule contents is suggested.