Escherichia coli

About: Escherichia coli is a research topic. Over the lifetime, 59041 publications have been published within this topic receiving 2050337 citations. The topic is also known as: E. coli & E coli jdj.

The transmissible nature of the genetic factor in Escherichia coli that controls haemolysin production.

Abstract: SUMMARY: A genetic factor (designated Ent) responsible for enterotoxin production in six of 51 enterotoxigenic strains of Escherichia coli of porcine origin could be transmitted to other strains of E. coli and to Salmonella typhimurium and S. choleraesuis by conjugation in mixed culture. A high proportion of organisms of the recipient strains in these cultures was found to have accepted Ent, which was probably a plasmid. The possession of Ent by an organism was a stable characteristic; no organisms were found to have lost it during either laboratory cultivation, acriflavine treatment, or residence in the alimentary tract of pigs and mice. Ent could be transmitted independently of F, R, Hly and K88 factors; the transfer factor responsible for its transmission closely resembled F and the transfer factors of fi + R factors and Hly. Ent+ organisms could not be differentiated from Ent− ones, morphologically, culturally or antigenically. The oral administration of enterotoxin-containing bacteria-free culture fluid of an Ent+ strain of E. coli had no apparent ill effect on pigs, piglets and calves; neither did the fluid influence skin permeability. The transmission of Ent to S. typhimurium and S. choleraesuis did not affect their pathogenicity. Three of four piglets given Ent+ E. coli organisms developed diarrhoea; three given Ent− organisms of the same strain did not.

Molecular cloning, characterization, and complete nucleotide sequence of the gene for pneumolysin, the sulfhydryl-activated toxin of Streptococcus pneumoniae.

Abstract: A recombinant lambda bacteriophage has been isolated that carries DNA from Streptococcus pneumoniae and expresses a potent hemolysin that has been shown to be pneumolysin, the sulfhydryl-activated toxin of the pneumococcus. Hemolytic activity is inhibited by cholesterol and neutralized by serum against streptolysin O. The cloned gene expresses two polypeptides (Mrs, 56,000 and 53,000) in an Escherichia coli in vitro transcription-translation system, and both are precipitated by the addition of anti-alveolysin serum and anti-streptolysin O serum in the presence of Staphylococcus aureus cells. Expression of pneumolysin occurs when the gene is cloned in both possible orientations in pUC8. The DNA sequence of a 5-kilobase ClaI fragment that carries the pneumolysin gene has been determined. An open reading frame was identified that encodes a polypeptide of 471 amino acids that is hydrophobic in character and has an N-terminal amino acid sequence which is identical to that deduced from amino acid sequencing of the purified protein. The predicted amino acid sequence of the polypeptide reveals a single cysteine residue located 44 residues from the C terminus. Putative promoter and ribosome binding sites have been identified 59 to the pneumolysin coding sequence. Images

Expression in Escherichia coli of hepatitis B virus DNA sequences cloned in plasmid pBR322.

Abstract: Fragments of hepatitis B virus DNA isolated from Dane particles have been inserted into the Escherichia coli plasmid pBR322 and cloned. Cells carrying the hybrid plasmid synthesise antigenic material that reacts specifically with antisera to hepatitis B viral antigens.

Methionine aminopeptidase gene of Escherichia coli is essential for cell growth.

Abstract: We localized the methionine aminopeptidase (map) gene on the Escherichia coli chromosome next to the rpsB gene at min 4. Genetically modified strains with the chromosomal map gene under lac promoter control grew only in the presence of the lac operon inducer isopropyl-beta-thiogalactoside. Thus, methionine aminopeptidase is essential for cell growth.