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.

Dna sequence, plasmid and production of lipase

Abstract: PURPOSE:To efficiently produce lipase, by inserting a structural gene of 1,3-position specific lipase of a bacterium of genus Pseudomonas and a structural gene of thermostable lipase of a bacterium belonging to the genus Bacillus into a multicopy plasmid and transducing Escherichia coli. CONSTITUTION:Chromosome DNA of Pseudomonas fragi IFO3458 strain is digested with restriction enzyme Sau3A, linked with pUC9 cleft by BamHI and T ligase, Escherichia coli JM83 is transduced and pHB-1.0 containing DNA sequence corresponding to amino acid sequence shown by the formula (A is Ileu; X is His; Y is Gln; B is Ala) is obtained from JM83 (pKK-O). DNA sequence corresponding to an amino acid sequence shown by the formula (A is Ala; X is Leu; Y is Leu; B is Gly) is also contained in plasmid PHS-6 having DNA fragment of HindIII-SaI derived from chromosome DNA of Bacillus stearothermophilus and Escherichia coli transduced with the plasmid is cultivated in a medium to give lipase.

Surface‐layer protein extracts from Lactobacillus helveticus inhibit enterohaemorrhagic Escherichia coli O157:H7 adhesion to epithelial cells

Abstract: Adherence of intestinal pathogens, including Escherichia coli O157:H7, to human intestinal epithelial cells is a key step in pathogenesis. Probiotic bacteria, including Lactobacillus helveticus R0052 inhibit the adhesion of E. coli O157:H7 to epithelial cells, a process which may be related to specific components of the bacterial surface. Surface-layer proteins (Slps) are located in a paracrystalline layer outside the bacterial cell wall and are thought to play a role in tissue adherence. However, the ability of S-layer protein extract derived from probiotic bacteria to block adherence of enteric pathogens has not been investigated. Human epithelial (HEp-2 and T84) cells were treated with S-layer protein extract alone, infected with E. coli O157:H7, or pretreated with S-layer protein extract prior to infection to determine their importance in the inhibition of pathogen adherence. The effects of S-layer protein extracts were characterized by phase-contrast and immunofluorescence microscopy and measurement of the transepithelial electrical resistance of polarized monolayers. Pre-treatment of host epithelial cells with S-layer protein extracts prior to E. coli O157:H7 infection decreased pathogen adherence and attaching-effacing lesions in addition to preserving the barrier function of monolayers. These in vitro studies indicate that a non-viable constituent derived from a probiotic strain may prove effective in interrupting the infectious process of an intestinal pathogen.

Organization of Escherichia coli O157 O Antigen Gene Cluster and Identification of Its Specific Genes

Abstract: The O157:H7 clone of Escherichia coli, which causes major, often prolonged outbreaks of gastroenteritis with hemolytic-uremic syndrome (HUS) such as those in Japan, Scotland, and the United States recently, is thought to be resident normally in cattle or other domestic animals. This clone is of major significance for public health and the food industry. We have developed a fast method for sequencing a given O antigen gene cluster and applied it to O157. The O157 O antigen gene cluster is 14 kb in length, comprising 12 genes and a remnant H-repeat unit. Based on sequence similarity, we have identified all the necessary O antigen genes, including five sugar biosynthetic pathway genes, four transferase genes, the O unit flippase gene, and the O antigen polymerase gene. By PCR testing against all 166 E. coli O serogroups and a range of gram-negative bacterial strains, including some that cross-react serologically with E. coli O157 antisera, we have found that certain O antigen genes are highly specific to O157 E. coli. This work provides the basis for a sensitive test for rapid detection of O157 E. coli. This is important both for decisions on patient care, since early treatment may reduce the risk of life-threatening complications, and for detection of sources of contamination. The method for fast sequencing of O antigen gene clusters plus an ability to predict which genes will be O antigen specific will enable PCR tests to be developed as needed for other clones of E. coli or, once flanking genes are identified, clones of any gram-negative bacterium.

Enzymatic breakage and joining of deoxyribonucleic acid, I. Repair of single-strand breaks in DNA by an enzyme system from Escherichia coli infected with T4 bacteriophage.

Abstract: Enzymatic breakage and joining of preformed polynucleotide strands has been implicated in molecular recombination, the repair of ultraviolet-irradiated DNA, and the interconversion of linear and circular DNA molecules.' A possible intermediate, in each of these processes, is a duplex DNA molecule containing phosphodiester bond interruptions (single-strand breaks). This paper describes the purification and some properties of an enzyme system, polynucleotide ligase, which catalyzes the repair of single-strand breaks by the formation of phosphodiester bonds (Fig. 1). The enzyme system has been purified from Escherichia coli infected with T4 bacteriophage and found to require ATP for activity.