Production, partial purification and characterization of Salmonella heat-labile enterotoxin

A heat-labile enterotoxin possessing both diarrheogenic and skin permeability reactions has been isolated from Salmonella weltevreden. The enterotoxin was mainly located intracellularly in the cell wall fraction. By chemical and physical techniques such as EDTA treatment of cell walls, fractional ammonium sulphate precipitation and continuous sucrose gradient centrifugation of cell sap (cell free extract) and gel filtration chromatography of culture supernatant, the enterotoxin has been partially purified. The enterotoxin resembled the heat labile enterotoxin of E. coli and the cholera toxin with respect to its thermal stability; however, it was different in its sensitivity to acidic and alkaline pH. Its activity was lost completely on treatment with Pronase and trypsin. The toxin appears to be of a high molecular weight and its enterotoxic activity is associated with a protein moiety.