K1F resistant Escherichia coli genome sequencing and assembly. Escherichia coli strain:EV36

The pathogenicity of Escherichia coli is often associated with the presence of the polysialic acid K1 capsule. The bacteriophage K1F, known to target the this K1 capsule. We exposed the K1 expressing strain EV36 to this phage and collecting the resultant resistant mutants. Of these mutants, two were of particular interest. The first of these showed full resistance to K1F and was found to have disruptions to the kpsE gene of the polysialic acid biosynthetic gene cluster, the product of which is involved in polysialic acid translocation. The second, on the other hand showed only partial resistance to K1F and disruptions to neuC, a gene involved in one of the early steps of polysialic acid biosynthesis. These disruptions were both found to be caused by genomic alterations caused by insertion sequences. Both strains also showed considerable phenotypic differences in presence and location of the K1 capsule, when compared to the wild type using confocal microscopy. In line with these findings, these K1F resistant mutants showed susceptibility to T7, a bacteriophage whose activity is normally blocked by the K1 capsule.