Abstract
Large amounts of alkaline phosphatase and 2, 3-cyclic phosphodiesterase were released into the culture medium during the active growth of heptose-deficient mutants of Escherichia coli NS1 to NS3, but no periplasmic enzymes were released from cells of the wild type strain JE. The NS mutants were hyper-sensitive to lysozyme, ethylenedia-minetetraacetate (EDTA), sodium deoxycholate (DOC), sodium dodecyl sulfate (SDS), and Triton X100; the sensitivity to detergent was increased several fold when the treatment was carried out in the presence of potassium cyanide. The wild type strain was not sensitive to lysozyme or detergents, even in the presence of KCN. Both the wild type and mutant strains were sensitive to colicins, E1, E2, E3, G, H, and K, and to phages T2, T3, T6, and BF23, but they were resistant to phages P22, FO, Ffm, 6SR, Br2, Br60, C21, and T5. Unlike the wild type strain, the NS mutants were resistant to phages T4, T7, and Br10. A comparison of the protein composition of the outer membrane of wild type and NS1 strains indicated that one major protein species of molecular weight (mol. wt.) 50, 000 was absent while two other proteins of mol. wt. 40, 000 and 33, 400 were present only in reduced amounts in the outer membrane of the NS1 mutant. These observations suggest that both the polysaccharide and protein components of the outer membrane of E. coli participate in the normal functioning of the outer membrane as a ‘permeability barrier.’
