Lipopolysaccharide core mutants of Salmonella typhimurium containing D-glycero-D-manno-heptose

Abstract

Mutants resistant to several hydrophobic membrane antagonists were isolated from a 'deep rough' (rfaC) mutant of S. typhimurium. The resistance was due to an alteration in the core region lipopolysaccharide composition as evidenced by altered bacteriophage and complement sensitivity and by compositional analysis. The principal change in carbohydrate composition was the predominance of the unusual heptose isomer D-glycero-D-manno-heptose. The unusually wide pleiotropic phenotype of this organism is suggested to be due to a fundamental change in the properties of the bacterial outer membrane.