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Chloramphenicol has a broad spectrum of activity and has been effective in treating ocular infections such as conjunctivitis, blepharitis etc. caused by a number of bacteria including Staphylococcus aureus, Streptococcus pneumoniae, and Escherichia coli. It is not effective against Pseudomonas aeruginosa.
While E. coli BL21(DE3) supports the expression of genes under the control of constitutive promoters, it is specifically engineered for IPTG induction of recombinant genes under the control of a T7 promoter. The realized induction strength depends on several factors, including the IPTG concentration and the timing of its supplementation. [5]
The crystal structure of the type III enzyme from Escherichia coli with chloramphenicol bound has been determined. CAT is a trimer of identical subunits (monomer Mr 25,000) and the trimeric structure is stabilised by a number of hydrogen bonds, some of which result in the extension of a beta-sheet across the subunit interface.
Agar dilution is one of two methods (along with broth dilution) used by researchers to determine the minimum inhibitory concentration (MIC) of antibiotics. It is the dilution method most frequently used to test the effectiveness of new antibiotics when a few antibiotics are tested against a large panel of different bacteria.
E. coli is a gram-negative, facultative anaerobe, nonsporulating coliform bacterium. [18] Cells are typically rod-shaped, and are about 2.0 μm long and 0.25–1.0 μm in diameter, with a cell volume of 0.6–0.7 μm 3. [19] [20] [21] E. coli stains gram-negative because its cell wall is composed of a thin peptidoglycan layer and an outer membrane.
CTX-M-15-positive E. coli are a cause of community-acquired urinary infections in the UK, [27] and tend to be resistant to all oral β-lactam antibiotics, as well as quinolones and sulfonamides. Treatment options may include nitrofurantoin, fosfomycin, mecillinam and chloramphenicol.
pBR322 is a plasmid and was one of the first widely used E. coli cloning vectors. Created in 1977 in the laboratory of Herbert Boyer at the University of California, San Francisco, it was named after Francisco Bolivar Zapata, the postdoctoral researcher and Raymond L. Rodriguez. The p stands for "plasmid," and BR for "Bolivar" and "Rodriguez."
The minimum inhibitory concentration, which is the lowest concentration of the antibiotic that stops the growth of bacteria, can be estimated from the size of the zone of inhibition. Antibiotic susceptibility testing has been needed since the discovery of the beta-lactam antibiotic penicillin. Initial methods were phenotypic, and involved ...