Conjugation deficient E. coli K12 F- mutants with heptose-less lipopolysaccharide

Two F- mutants deficient in conjugation with F-type donors are isolated and characterized. Phenotypically, these mutants are similar; they have heptose-less lipopolysaccharide and lack some outer membrane protein. Genotypically, they are different. One mutant harbors a point mutation in the 70 to 74 min region, while the other is deleted for the chromosomal region 6.5 to 8.5 min. Comparison of the properties of the conjugation-deficient mutants described in this paper with other such mutants suggests that an outer membrane protein is the receptor for the f-pilus.