Studies of colicin action on wall-less stable L-forms of Escherichia coli. II. Growth inhibition of complete and wall-less (L-form) cells of Escherichia coli by basic colicin types.

The inhibitive activity of colicins of 16 types (produced by 22 colicinogenic strains) on rods and protoplast-like stable L-form cells of the strains Escherichia coli B, W1655 F+ and W1655 F− was compared. The results of 58 combinations tested fall into four groups (with three subgroups): 1) both cell forms are sensitive a) both cell forms are about equally sensitive b) rods are distinctly more sensitive than L-form cells c) L-form cells are distinctly more sensitive than rods 2) only rods are sensitive, L-form cells are not sensitive 13) only L-form cells are sensitive rodsare not sensitive 4) neither cell form is sensitive. Group la represents simple sensitivity; both cell wall and cytoplasmic membrane receptors are present and functioning. Groups 1b and 2 represent sensitivity, substantially or completely mediated by cell wall receptors. Groups 1 c and 3, represent partial or complete “pseudoresistance” or “pseudotolerance”; cell wall receptors are absent or non-lethal, but cytoplasmic membrane ones are present and mediate the lethal effect. Group 4 represents both true resistance and true tolerance.