RESTRICTION IN MATINGS OF ESCHERICHIA COLI STRAIN K-12 WITH STRAIN B

The beta-d-galactosidase of Escherichia coli, strain K-12.

Effacing Escherichia coli 045:K"E65" Strain

The ability of a nonenterotoxigenic, K88-negative porcine Escherichia coli strain of serogroup 045:K"E65" to induce attaching-effacing lesions was investigated in newborn pigs. Typical attaching-effacing lesions, characterized by intimate adherence of bacteria to mature enterocyte brush borders with effacement of the microvilli, were observed on light and electron microscopy. Bacteria were also...

Strain variation in ppGpp concentration and RpoS levels in laboratory strains of Escherichia coli K-12.

Laboratory strains and natural isolates of Escherichia coli differ in their level of stress resistance due to strain variation in the level of the sigma factor sigma(S) (or RpoS), the transcriptional master controller of the general stress response. We found that the high level of RpoS in one laboratory strain (MC4100) was partially dependent on an elevated basal level of ppGpp, an alarmone res...

Isoleucine and valine metabolism of Escherichia coli. XVI. Pattern of multivalent repression in strain K-12.

The levels of the five enzymes required for isoleucine and valine synthesis were examined under several growth conditions in strain K-12 of Escherichia coli and mutants derived from it. In strains with wild type repressibility, the same pattern of derepression was found on limiting isoleucine as is found to be constitutive in strain Tir-8, which has an altered isoleucine-activating enzyme. Homo...

Mapping by transposons of the inversion termini in Escherichia coli K-12 strain 1485IN.

Strain 1485IN carries a chromosomal inversion which corresponds to 35% of the chromosome and includes proC, trp and his genes. The termini of the inversion lie between the lac and proC loci and between his and cdd of the normal strain. Using Tn10 and Tn5 in transduction crosses between the normal and inversion strains, the termini were mapped to sites located approximately 0.25 min and 1.6 min ...