Analytical techniques of toxins
Rapid results. .g. BTA test strip for C. botulism
BTA test strip for Staphylococcal Enterotoxin
High performance Liquid Chromatography (HPLC)
-Detection of very small amt. of toxins by using fluorescence detector.
-Gives better results when coupled with Atmospheric Pressure/ Electrospray Ionisation (API/ESI)
Detection of toxins of Bacillus cereus
Gene detection techniques can be applied including PCR.PCR primers for the detection of these genes were used to detect the genes. A commercial immunoassay (Tecra visual immunoassay [VIA]) is used for identification of enterotoxic strains of B. cereus. The gene was cloned and sequenced from B. cereus. For DNA preparation, bacteria were plated on agar and incubated overnight at 30°C. An amount of bacteria corresponding to a colony 1 to 2 mm in diameter was transferred to Tris-EDTA buffer. Bacteria were lysed by incubation, and debris was removed by centrifugation. The DNA-containing supernatant was transferred to a new Microfuge tube and stored. Primers for detection of gene were given. PCR was performed essentially. PCR products were analyzed by agarose gel electrophoresis.
Detection of staphylococcal enterotoxin
For detecting trace amounts of staphylococcal enterotoxin in foods, the toxin must be separated from food constituents and concentrated before identification by specific precipitation with antiserum. The principles are used for the purpose: the selective adsorption of the enterotoxin from an extract of the food onto ion exchange resins and the use of physical and chemical procedures for the selective removal of food constituents from the extract, leaving the enterotoxin(s) in solution.
Developed rapid methods based on monoclonal antibodies like the ELISA and Reverse Passive Latex Agglutination are used for detection of enterotoxins. The principle of using ELISA is by binding an immunosorbent substrate onto either the enzyme or the antibody. They both retain their biologic activity; the change in enzyme activity as a result of the enzyme-antibody-antigen reaction is proportional to the concentration of the antigen and can be measured spectrophotometrically.