Lysogenic strain

Certain strains of Escherichia coli can be stimulated by irradiation with a moderate dose of ultraviolet (UV) light to stop normal growth and start producing bacteriophages that eventually lyse the bacterium. Bacteria of these so-called lysogenic strains carry the DNA of the phage integrated into their own... 

Toxins capable of catalyzing such a reaction include diphtheria toxin, secreted by lysogenic strains of Corynebacterium diphtheriae carrying the phage-encoded toxin gene (DT), and the exotoxin A from Pseudomonas aeruginosa (ETA). Both catalyze the ADP-ribosylation of a posttranslationally-modified histidine residue (called diphthamide) in EF-2. 

The minimum concentration of lavendamycin (0.003 /Ag/ml) required to induce bacteriophage production in the lysogenic strain of Escherichia coli W1709 was found to be comparable to that of streptonigrin (0.008 pg/ ml) (57). 

Diphtheria toxin, a protein secreted by lysogenic strains of Corynebacterlum dlphtherlae, has been shown to be an effective inhibitor of the growth of Ehrlich carcinoma, both ascitic and solid, in mice. The effect is thou to be mediated primarily through inhibition of protein synthesis. Similarly, the parasporal crystal ( S -endotoxin) of B. thuringiansis has been reported to exertj tent anti-Yoshlda ascites carcinoma activity, with a hi therapeutic index . 

Deutsch, S.M., Ferain, T., Delcour, J., and Lortal, S. (2002) Lysis of lysogenic strains of Lactobacillus helveticus in Swiss cheeses and first evidence of concomitant Streptococcus thermophilus lysis. Int Dairy J 12, 591-600. 

The induction of a lysogenic culture to produce infectious phages, followed by lysogenization of a second strain of the bacterial species by these phages, results in the... 

It is sometimes possible to eliminate the lysogenic virus (to cure the strain) by heavy irradiation or treatment with nitrogen mustards. Among the few survivors may be some cells that have been cured. Presumably the treatment causes the prophage to detach from the host chromosome and be lost during subsequent cell growth. Such a cured strain is no longer immune to the virus and can serve as a suitable host for study of virus replication. 

E. coli host strain AR58 containing defective phage lambda lysogen transformed with a recombinant vector which carries antibiotic resistance for kanamycin (Kan R). 

Pyrolysis products were also found to induce prophage X in lysogenic E. ooli K12, strain GY5027 (30), by Inductest III, which was developed by Moreau et al, (31) (Figure 2). The genotoxic effects of pyrolysis products on cultured mammalian cells were also investigated. Trp-P-1, Trp-P-2, IQ and MelQ were found to induce diphtheria toxin-resistant mutants of Chinese hamster lung cells in the presence of S9 mix. The mutation frequencies were 33, 160, 40 and 38 per 106 survivors per Mg of Trp-P-1, Trp-P-2,... 

A wide variety of E coli strains designed for protein expression are commercially available, derived from the E. coli strain BL21, that are tailored to facilitate disulfide bond formation, fine-tune protein expression levels, enhance the expression of proteins that contain rare codons, and other specific requirements. These strains are available as lambda DE3 lysogens, which carry a chromosomal copy of the T7 RNA polymerase gene under control of the lac promoter (inducible by IPTG). Once induced, the T7 RNA polymerase drives expression of genes that are under control of the T7 promoter, such as those cloned into the pET family of expres-... 

S. Vasilukova, nee Reslova, a young Czechoslovakian microbiologist, and an ex-student of J. Drobnik who contributed much to our microbial experiments, worked with strains of E. coli bacteria that had been previously infected with a bacterial virus (A-bacteriophage). In these lysogenic bacteria, the genetic information of the virus has been incorporated into the cell, but it is repressed so that it is not normally detectable. It replicates during cell division along with the bacterial DNA and so is not lost or diluted out after many divisions. 

Eriksson, S., Sj berg, B.-M., and Hahne, S., 1977, Ribonucleoside diphosphate reductase from Escherichia coli. An immunological assay and a novel purification from an overproducing strain lysogenic for phage Xdnrd. J. Biol. Chem. 252 613296138. 

Diphtheria toxin is the main pathogenicity factor in diphtheria (Pappen-heimer, 1977). The toxin gene is carried by a bacteriophage, p, which is lysogenic in Corynebacterium diphtheriae. Toxigenic strains of the bacteria cause local infection of the throat. After recovery from the acute phase of the disease, life-threatening organ complications often occur, mainly in the heart, which are due to toxin produced by the bacteria in the throat and released into the circulation. Due to mass vaccination, the disease is now almost extinct in developed countries. 

One of the primary killers of children prior to immunization was upper respiratory tract infections by Corynebacterium diphtheriae. Toxin produced by a lysogenic phage that is carried by some strains of this bacteria causes the lethal effects. It is lethal in small amounts because it blocks protein synthesis. The viral toxin is composed of two parts. The B portion binds a cell s surface and injects the A portion into the cytosol of cells. The A portion ADP-ribosylates a histidine-derived residue of the elongation factor 2 (EF-2) known as diphthamide. This action completely blocks the ability of EF-2 to translocate the growing polypeptide chain. 

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