Genetic and physiological classification of periplasmic-leaky mutants of Salmonella typhimurium.

Mutants of Salmonella typhimurium that leaked periplasmic proteins were isolated. Four classes of mutants were identified by their increased sensitivity to dyes, detergents, or antibiotics. Conjugation studies indicated that representatives of two classes mapped in the proA-galE region of the Salmonella chromosome and two in the cysI-argE region. According to their bacteriophage sensitivity pattern, all four of the mutant classes appear to retain the smooth lipopolysaccharide characteristic. One class of mutants has an abnormal cell envelope in which the outer membrane balloons away from the murein layer.