Comparison of different purification procedure for extraction of staphylococcal enterotoxin A from foods

Abstract

Different procedures commonly used for extraction, purification, and concentration of staphylococcal enterotoxins from foods were investigated with 13'I-and '251-labeled staphylococcal enterotoxin A. Loss of labeled enterotoxin A was compared with loss of total nitrogen. The results showed that in most of the common procedures, such as gel filtration, ion exchange, and heat treatment, the percentage of loss of labeled enterotoxin A was greater than the loss of total nitrogen. Chloroform extraction and acid precipitation with hydrochloric acid had nearly the same effect on the purification of both labeled enterotoxin A and total nitrogen. Ammonium sulfate precipitation proved to be practical and was successfully used for purification of enterotoxin A from sausage extract. Simultaneous use of trypsin and Pseudomonas peptidase for treatment of food extracts considerably reduced food proteins capable of interfering with serological detection of enterotoxins but did not essentially influence the loss of enterotoxin A.

Staphylococcal Food Poisoning and Novel Perspectives in Food Safety

“…Although SEB was reported to be produced in much larger quantities and more diverse among strains than SEA, SEA had been implicated in a larger number of food poisoning cases [63]. Resembling a primary metabolite (with SEB as a secondary metabolite), SEA is secreted by the bacterium during the exponential phase of growth, with various of factors affecting its production, including salt concentration (NaCl, NaNO 2 , and NaNO 3 showing no influence), surfactants (increase in SEA secretion), pH (optimal ranging from 6.5 to 7.0), and antimicrobial agents (inhibition by chloramphenicol or 2,4-dinitrophenol, with streptomycin or penicillin G exhibiting no influence), which may explain the higher frequency and incidence of SEA in food poisoning [63][64][65][66]. In addition, temperature and inoculum size play important roles in SEA production.…”

Preparation of labeled staphylococcal enterotoxin A with high specific activity

“…lodination of SEA. SEA was labeled by a modification of the method of Greenwood and Hunter (5,6) as described previously (9), except that [1251]SEA was fractionated from free 1251with a Sephadex G-75 column (1.3 by 20.0 cm) for better separation of aggregate. The amounts of reagents and reaction conditions are listed in Table 1.…”