SALMONELLA-TYPHIMURIUM TNPHOA MUTANTS WITH INCREASED SENSITIVITY TO BIOLOGICAL AND CHEMICAL DETERGENTS

Salmonella typhimurium is a ubiquitous pathogenic bacterium able to su stain the environmental conditions of the gastrointestinal tract, incl uding biliary salts. To understand the mechanisms involved in bile sal t resistance and, more generally, detergent resistance, we investigate d S. typhimurium mutants produced with the random mutagenic TnphoA tra nsposon. A total of 3,000 transpositional mutants were isolated, Three strains among the 1,432 first mutants lost the ability to grow in the presence of biological and chemical detergents. They were prototrophi c and exhibited normal lipopolysaccharide and outer membrane protein p rofiles after SDS-PAGE. They did not show sensitivity to dyes but show ed very different sensitivities to antibiotics. For each mutant strain , Southern blotting analysis revealed a unique TnphoA insertion at dif ferent chromosomal locations. These observations were confirmed by tra nsduction experiments.