Biochemical and Topographical Studies on the Cell Surface of Escherichia coli

I. Isolation and Characterization of Detergent-sensitive Mutants

Abstract

1) Based on selection through differential sensitivity to sodium dodecylsulfate (SDS) and Triton X100, 12 ethyl methanesulfonate-induced Escherichia coli mutants with altered cell surfaces were isolated and classified into 3 groups: a) sensitive only to 5% SDS, b) sensitive to 0.5% SDS but insensitive to 5% Triton, c) sensitive to both 0.5% SDS and 5% Triton. Three representative strains of each group were characterized in comparison with the parent strain K-12: W3110 and with an oleic acidrequiring mutant, ONO-3, which also showed a slightly enhanced sensitivity to SDS.
2) The strain ONT-3 of group c) was found to be most susceptible to cell lysis caused by detergents or membrane-active antibiotics among the 5 strains tested, but had the highest resistance to a cell-wall active antibiotic, cycloserine.
3) The strain ONS-2 of group b) was second most susceptible to SDS-induced cell lysis. Bacitracin and novobiosin, which are cell-wall synthesis inhibitors also having the activity to attack plasma membrane, inhibited this strain more than any other mutants tested.
4) SDS-semisensitive strains, ONS-39 of group a), as well as ONO-3, showed surface properties almost the same as those of the parent strain, except for the sensitivity to SDS.
5) No essential difference in macromolecular synthesis or in cellular metabolic activity was found between these 4 mutants and the parent strain.