Production of vero cytotoxin by Escherichia coli and Shiga toxin by Shigella dysenteriae 1 as related to the growth medium and availability of iron.
Six strains of Escherichia coli producing Vero cytotoxin (VTEC) and six strains of Shigella dysenteriae 1 were examined for the production of extra- and intracellular Vero cytotoxin (VT) and Shiga toxin respectively, in relation to the growth medium and availability of iron. VTEC secreted less extracellular VT1 or VT2 when grown in trypticase soy broth (TSB) containing the iron chelator desferal, as compared to bacteria cultured in iron replete TSB. Growth in TSB containing desferal resulted in increased production of intracellular toxin by VT1 producing strains of E. coli; but had little effect on production of intracellular toxin by VT2 producing strains. Both extra- and intracellular levels of Shiga toxin were increased by growth in TSB containing desferal. Combining intra- and extracellular toxin titres, strains of E. coli producing VT1 gave highest titres following growth in TSB where iron was bound to the chelating agent desferal, while strains of S. dysenteriae 1 produced highest levels of toxin when grown in syncaseglucose broth made iron depleted using Chelex-100. Strains of S. dysenteriae 1 did not grow in syncase-glucose broth containing desferal.
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Division of Enteric Pathogens, Central Public Health Laboratory, London, U.K.
Scotland
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Rowe
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D000818:Animals; D001427:Bacterial Toxins / Q000096:biosynthesis*; D002522:Chlorocebus aethiops; D003470:Culture Media; D003603:Cytotoxins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000254:growth & development / Q000378:metabolism*; D007501:Iron / Q000378:metabolism; D007502:Iron Chelating Agents; D022622:Shiga Toxin 1; D022603:Shiga Toxins; D012762:Shigella dysenteriae / Q000254:growth & development / Q000378:metabolism*; D014709:Vero Cells
D001427:Bacterial Toxins; D003470:Culture Media; D003603:Cytotoxins; D007502:Iron Chelating Agents; D022622:Shiga Toxin 1; D022603:Shiga Toxins; D007501:Iron