SERINE METABOLISM IN A MUTANT STRAIN OF ESCHERICHIA COLI STRAIN K-12

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

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...

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...

D-serine transport system in Escherichia coli K-12.

The d-serine transport system in Escherichia coli K-12 was studied by use of a mutant unable to form d-serine deaminase, yet resistant to d-serine. The mutant is greatly impaired in its ability to accumulate d-serine, d-alanine, and glycine. Transport of l-alanine is partially affected but transport of l-serine is unaffected. The mutant is also resistant to d-cycloserine, indicating that d-seri...

Construction of an iss deleted mutant strain from a native avian pathogenic Escherichia coli O78: K80 and in vitro serum resistance evaluation of mutant

BACKGROUND: Colibacillosis, caused by different serotypes of avian pathogenic Escherichia coli (APEC), is one of the important diseases in poultry industry. The isolate O78 is the most prevalent serotype of APEC in Iran. One of the APEC virulence factors, increased serum survival (iss) gene, is related to serum resistance. The usual form of colibacillosis in avian is extraintestinal, and serum ...