Beta-toxin was purified about 340-fold from culture supernatant fluid of Clostridium perfringens type C with a yield of about 24% in terms of biologically active beta-toxin. The purification involved ammonium sulfate fractionation, gel filtration through Sephadex G-100, isoelectrofocusing in a pH 3 to 6 gradient, and immunoaffinity chromatography. The purified beta-toxin gave a single band on p...

Concentrations of antibiotics below the MIC are able to modulate the expression of virulence-associated genes. In this study, the influence of subinhibitory doses of 31 antibiotics on the expression of the gene encoding the staphylococcal alpha-toxin (hla), a major virulence factor of Staphylococcus aureus, was investigated with a novel gene fusion protocol. The most striking observation was a ...

Seed contamination with polyketide mycotoxins, including aflatoxin (AF) and sterigmatocystin (ST) produced by Aspergillus spp., is an agricultural, economic, and medical issue worldwide. Acetyl-CoA, the fundamental building block of all known fungal polyketides, is generated by a large number of biochemical pathways, including beta-oxidation of fatty acids and glycolysis of sugars. We present s...

Beta toxin is a neutral sphingomyelinase secreted by certain strains of Staphylococcus aureus. This virulence factor lyses erythrocytes in order to evade the host immune system as well as scavenge nutrients. The structure of beta toxin was determined at 2.4-A resolution using crystals that were merohedrally twinned. This structure is similar to that of the sphingomyelinases of Listeria ivanovii...

Iota toxin is produced by Clostridium perfringens type E. This toxin causes antibiotic-associated enterotoxemia in lambs and calves. Iota toxin is a binary toxin that has two components including Ia (the enzyme component) and Ib (the binding component). Ib binds to the surface receptor of target cells and translocate Ia into the cytosol of cells. The aim of this study was to clone toxigenic epi...

Beta-toxin is one of the lethal toxins of Clostridium perfringens. It shares sequence homology with the pore-forming alpha-toxin of Staphylococcus aureus and structural homology has been indicated by mutagenesis studies. Human endothelial cells are sensitive to the toxic effect of alpha-toxin and in order to investigate the function of beta-toxin we have looked at the effect of the protein on h...

The interaction of two Bacillus thuringiensis cytolytic toxins, CytA and CytB, with a phospholipid bilayer and their structure in the membrane-bound state were investigated by proteolysis using phospholipid vesicles as a model system. A toxin conformational change upon membrane binding was detected by comparing the proteolytic profile of membrane-bound toxin and saline-solubilized toxin. When m...

objective(s) production of extended-spectrum beta-lactamases (esbls) by enteric bacteria continues to be a major problem in hospitals and community. esbls producing bacteria cause many serious infections including urinary tract infections, peritonitis, cholangitis and intra-abdominal abscess. the aim of this study was to determine the prevalence of esbls producing escherichia coli and klebsiell...